Original article
An autopsy study of sudden cardiac death in persons aged 1–40 years in Brescia (Italy) Marzia Vassalini, Andrea Verzeletti, Mario Restori and Francesco De Ferrari Introduction Sudden cardiac death (SCD), above all when occurring in young people, remains a major clinical problem. We have analysed the clinical and post mortem findings of patients who were evaluated for SCD.
12 cases (22.2%), in whom the heart was structurally normal at macroscopic examination. Despite all the investigations carried out, any pathogenic substrate that could have justified death was not found in 12 cases (22.2%).
Methods and results We have analysed 54 cases of SCD which occurred in patients aged below 40 years during the period 1993–2012 and were studied at the Institute of Forensic Medicine of Brescia. The following variables were considered: sex, age, medical history, autopsy findings with special reference to macroscopic and histological evaluation of the heart and toxicological investigation. In all cases, we also performed the dissection of the cardiac conduction tissue with subsequent serial sampling and careful microscopic evaluation.
Conclusion Our study underlines the value of an accurate routine post mortem investigation that may show an otherwise unsuspected structural heart disease. The serial study of the conduction tissue may provide pathologic substrates that may be responsible for the arrhythmic cause of death. A meaningful percentage of cases (22%) had no evidence of any abnormality. Genetic testing can be indicated in these cases.
Most SCD patients were men (76%), with a mean age of 27 years. The results of post mortem investigations have identified the following abnormalities: coronary artery disease (18.5%), arrhythmogenic right ventricular dysplasia (11.1%), hypertrophic obstructive cardiomyopathy (9.2%), severe valvular heart disease (7.4%) and myocarditis (7.4%). A case of persistence of the inter-atrial communication with cardiomegaly and right and left ventricular hypertrophy was also reported. Examination of the cardiac conduction tissue showed abnormalities in
Introduction Sudden unexpected death in young people is a rare event, but when it occurs, it is always tragic and of concern for families and physicians. Despite advances in the screening and the diagnosis of cardiovascular disease, sudden cardiac death (SCD) is often the first manifestation of an underlying heart problem in apparently healthy individuals. The incidence of SCD is not uniform depending on many factors such as sex, age, ethnic group, chronological criteria and methodology of diagnosis. A task force of the European Society of Cardiology has indicated that the incidence ranges from 36 to 128 deaths per 100 000 people per year.1,2 In the majority of the patients with a cardiac arrest, a structural or functional abnormality can be identified through routine post mortem investigations.3 Several authors examined morphological findings in SCD case studies: the relative importance of different causes of the fatal outcome varies among studies, coronary artery disease (CAD) being the most common.4 1558-2027 ß 2016 Italian Federation of Cardiology. All rights reserved.
J Cardiovasc Med 2016, 17:446–453 Keywords: conduction tissue, histological findings, molecular diagnosis, sudden cardiac death Department of Medical and Surgical Specialties, Radiological Sciences and Public Health, Section of Public Health and Human Sciences, Forensic Medicine Unit, University of Brescia, Brescia, Italy Correspondence to Marzia Vassalini, Istituto di Medicina Legale, Universita` degli Studi di Brescia, Piazzale Spedali Civili 1, 25123 Brescia, Italy Tel: +39 0303995480; fax: +39 0303995839; e-mail: [email protected] Received 27 May 2014 Revised 28 September 2014 Accepted 30 September 2014
A careful autopsy and an accurate gross and microscopic heart examination are necessary to formulate a correct diagnosis. The aim of this study is to describe the clinical and post mortem findings of patients who died suddenly and were evaluated at the Institute of Forensic Medicine of Brescia. All the patients were studied using strict standardized criteria including the microscopic examination of the cardiac conduction system (CCS).
Material and methods For the purpose of this study, we have analysed all the SCD cases which occurred between January 1993 and December 2012 in patients aged 1–40 years. Cases of sudden infant death syndromes (under 1 year of age) were ruled out. SCD is defined as an unexpected natural death that occurs instantaneously or within 24 h of the onset of symptoms or collapse,5,6 with autopsy exclusion of extracardiac causes and drug or alcohol abuse upon the post mortem toxicologic screening of blood and urine. DOI:10.2459/JCM.0000000000000234
© 2016 Italian Federation of Cardiology. All rights reserved.
Study of sudden cardiac death in Brescia (Italy) Vassalini et al. 447
For each death, the following data were collected: sex, age, circumstances of witnessed deaths, family history and retrospective clinical information. After excluding cases with a positive history of heart disease and cases of drug intoxication, a complete gross and histological study, including CCS, and toxicology were performed. After fixation in 10% buffered formaldehyde, the morphology of the heart was evaluated: heart weight, chamber size, wall thickness, longitudinal, transverse and antero-posterior diameters, endocardium and valve devices, coronary arteries (by taking transverse sections at 4-mm intervals), as well as myocardium and epicardial fat distribution. In agreement with the standards reported in the literature,7,8 multiple samples for histology were taken from three standard sites (anterior, lateral and posterior) of both ventricles and of the inter-ventricular septum, as well as sample from coronary walls (when affected by the presence of atherosclerotic plaques or thrombotic phenomena) and from lesions observed at gross examination. The study of the CCS was carried out by dissection into two blocks9: one obtained in order to study the sinusatrial node (SAN) and the other block excised for the examination of the atrio-ventricular junction (AVN) and its artery (His bundle and bundle branches). The blocks were processed through standard steps (an alcohol 95 washing, four 1,4-dioxane steps and one 1,4-dioxaneparaffin step); afterwards, they were embedded in paraffin and completely sectioned (5-mm serial section, with 20–30-mm intervals). The histological preparations were coloured with haematoxylin–eosin and trichrome Azan. In order to better evaluate the myofibres and arteriolar elastic fibres, Walsh and Weigert’s method was also used. Post mortem diagnosis was based on the criteria summarized in Table 1.10–17 Table 1
Results From the review of autopsy and external examination reports, we identified 54 SCD cases, accounting for 0.7% of the 7804 post mortem examinations conducted by the Institute of Forensic Medicine of Brescia over the 20-year study period (Table 2). There was a male predominance: 41 males (76%) and 13 females (24%). The median (inter-quartile range) age of the SCD population was 27 (22.25, 32.75) years, with an age range of 9–39 years. With respect to the clinical circumstances at the time of the SCD event, symptoms onset was during, or immediately before, physical activity (sport or work) in 12 cases (22.2%). Death occurred during sleep in eight cases (14.8%). Post mortem investigations have identified ischaemic abnormalities in 10 cases (18.5%) (Fig. 1): in 4 of these cases, there was a severe coronary disease with a concentric or eccentric stenosis of the vasal lumen greater than 70%, associated with ‘acute’ ischaemic abnormalities of the myocardium (erythrocytes infiltration, coagulation necrosis of the myocytes) (Fig. 1). Areas of myocardial sclerosis with moderate-grade coronary artery stenosis (40–50%) were found in the remaining six cases. A case of a young man aged 24 years, with autoptic finding of an anatomic abnormality of the coronary origin (right coronary ostium splitting), associated with the widespread presence of minute areas of interstitial fibrosis of the ventricular myocardium, was reported. In our study, the absence of SCD cases resulting from thrombotic events, plaque rupture or dissection of the coronary arteries should be taken into account. The average age of patients with CAD was equal to 31 years, with prevalence of male sex (seven cases) compared with that of females (two cases). With respect to the presence of congenital heart defects, we report only one case concerning a male patient, aged
Morphological findings in SCD cases
Diagnosis
Pathological abnormalities
Coronary artery disease (CAD)
Significant narrowing 70% of the cross-sectional coronary artery diameters, with signs of atherosclerosis, thrombosis, fibrous plaque fissuring or rupture and dissection10 Atrial septal defect (sinus venosus type, ostium primum type, ostium secundum type), inter-ventricular septal defect, Botallo’s persistent ductus arteriosus, aortic coarctation, tricuspid atresia and anomalies of origin of the coronary vases Thickening, fibrosis, deformation, retraction or myxomatous degeneration of the valve leaflets with a consequent stenosis or insufficiency of severe entity11 Asymmetrical or symmetrical left ventricular hypertrophy. Myocardial hypertrophy in the absence of any other cardiac or systemic disease that could cause it, with histological finding of extensive myofibre disarray12,13 Trans-mural fibrous and fatty myocardial replacement, either right ventricular or biventricular, associated with myofibre regressive changes in at least two sites of the ‘triangle of dysplasia’ (infundibulum, postero-basal right ventricular wall, anterior wall)14–16 Inflammatory infiltrates of myocardium with degeneration and/or necrosis of the adjacent myocytes17 Cardiac conduction system (CCS) abnormalities Absence of any abnormality at gross and histological analysis of the heart well as the examination of the cardiac conduction tissue
Congenital heart disease
Valve disease Hypertrophic cardiomyopathy (HCM)
Arrhytmogenic right ventricular cardiomyopathy (ARVC) Myocarditis ‘Apparently normal heart’ Sudden unexplained death (SUD)
© 2016 Italian Federation of Cardiology. All rights reserved.
448 Journal of Cardiovascular Medicine 2016, Vol 17 No 6
Table 2 Case
Demographic, clinical and autoptic data Sex
Age
Race
Circumstantial data
Heart weight
LV thickness
1
F
27
Caucasian
Death not witnessed
250 g
1 cm
2
F
29
Caucasian
Sudden death at rest
343 g
1.5 cm
3
M
29
Caucasian
Death during sport activity (football)
420 g
1.5 cm
4
M
26
Caucasian
Sudden death at rest (in a pub)
520 g
2.5 cm
5
M
22
Caucasian
383 g
1.2 cm
6
M
9
Caucasian
Death during sport activity (football) Death during sleep
180 g
1.5 cm
7 8
M M
25 27
Caucasian Caucasian
9
M
19
10 11
M M
12 13 14
Pathology findings CAD and myocardial sclerosis (atherosclerotic plaques of the left anterior descending coronary with narrowing equal to 50%; extensive areas of fibrosis in many left ventricular tissue) Mitral valve prolapse (increased leaflet thickness floppiness and redundancy of mitral valve; myxomatous changes) CAD and myocardial sclerosis (atherosclerotic plaques of three coronary vessels without significant narrowing; extensive areas of fibrosis in many left and right ventricular tissue) Mitral and aortic valve stenosis [parietal endocardium, mitral and aortic cusps markedly thickened with severe valve stenosis; coronary atherosclerotic plaques (maximum narrowing of 60%); disarray of myocardial fibres] CCS abnormalities (atrio-ventricular node erythrocytic infiltration; fibro-muscular hyperplasia of the AVN artery) Congenital heart disease (persistence of inter-atrial communication, ostium secundum type) HCM (symmetrical left ventricular hypertrophy) CCS abnormalities (atrio-ventricular node fetal marked dispersion and His bundle fragmentation with adipose insulation) Mitral valve stenosis (mitral cusps markedly thickened with severe valve stenosis) None (SUD) CAD [atherosclerotic plaques of three vessels (maximum narrowing of 60%); contraction band necrosis] HCM (symmetrical left ventricular hypertrophy) None (SUD) Mitral valve prolapse (increased leaflet thickness floppiness and redundancy of mitral valve; myxomatous changes) CAD [significant narrowing (>80%)of left main coronary; narrowing (40%) of left circumflex; anomalous insertion of the medial flap of the tricuspid] CCS abnormalities (silent atrio-ventricular accessory pathway) CAD [significant narrowing (90%) of left anterior descending artery; coagulation necrosis of the myocytes] ARVC (diffuse fibro-fatty replacement of the right wall)
480 g 354 g
3.2 cm 1.3 cm
Caucasian
Death not witnessed Death during work (metal worker) Sudden death at rest
363 g
2.7 cm
34 37
Caucasian Caucasian
Sudden death at rest Sudden death at rest
420 g 400 g
1.6 cm 1.7 cm
F F M
23 27 26
Caucasian Caucasian Caucasian
Death not witnessed Sudden death at rest Sudden death at rest
350 g 330 g 400 g
2.5 cm 1.3 cm 1.5 cm
15
M
39
Caucasian
Death during work (home builder)
300 g
1.5 cm
16 17
F M
22 30
Caucasian Caucasian
Sudden death at rest Death not witnessed
250 g 230 g
1 cm 1.5 cm
18
F
13
Caucasian
260 g
1 cm
19 20 21 22 23
F F F M M
35 24 28 34 20
Caucasian Caucasian Caucasian Negroid Caucasian
400 g 280 g 240 g 336 g 280 g
1.3 cm 1.2 cm 1.5 cm 2 cm 1.4 cm
ARVC (diffuse fatty replacement of the right wall) CCS abnormalities (silent atrio-ventricular accessory pathway) None (SUD) CCS abnormalities (silent atrio-ventricular accessory pathway) CCS abnormalities (silent atrio-ventricular accessory pathway)
24
M
38
Negroid
Death during sport activity (swimming) Sudden death at rest Sudden death at rest Death during sleep Sudden death at rest Death during sport activity (running) Death not witnessed
350 g
1.3 cm
25
M
15
Caucasian
Death during physical activity (at school)
250 g
1 cm
26
M
27
Caucasian
413 g
1.6 cm
27
M
31
Caucasian
Death during not specified work Sudden death at rest
Myocarditis (inflammatory infiltrates of myocardium with degeneration and/or necrosis of the adjacent myocytes) Myocarditis (inflammatory infiltrates of myocardium with degeneration and/or necrosis of the adjacent myocytes. Immunohistochemistry: CD4R0 positive; microbiological analyses: negative) None (SUD)
530 g
3 cm
28 29
F M
25 31
Caucasian Caucasian
Sudden death at rest Death not witnessed
260 g 420 g
1.1 cm 2.4 cm
30 31
M M
27 16
Caucasian Caucasian
Sudden death at rest Death not witnessed
435 g 350 g
1.5 cm 1 cm
32 33
M M
20 35
Caucasian Caucasian
Death not witnessed Death not witnessed
515 g 410 g
1.7 cm 1.7 cm
34
M
14
Caucasian
240 g
1 cm
35
M
26
Caucasian
450 g
1.8 cm
ARVC (segmental areas of fibro adipose replacement)
36 37 38 39
M M M M
29 32 35 17
Caucasian Indian Caucasian Caucasian
454 g 340 g 409 g 308 g
1.5 cm 1.3 cm 1.5 cm 1 cm
None (SUD) ARVC (segmental areas of fibro adipose replacement) ARVC (segmental areas of fibro adipose replacement) None (SUD)
40
F
38
Caucasian
Death during work (farmer) Death during sport activity (football) Death during sleep Sudden death at rest Death during sleep Death during sport activity (running) Sudden death at rest
400 g
1.6 cm
41
M
38
Caucasian
Death during sleep
450 g
1.7 cm
CAD (atherosclerotic plaques of the coronary tree; extensive areas of fibrosis in many left ventricular tissue) CCS abnormalities (atrio-ventricular node fetal marked dispersion and His bundle fragmentation with adipose insulation)
HCM (symmetrical left ventricular hypertrophy; disarray of myocardial fibres interesting inter-ventricular septum) None (SUD) HCM (symmetrical left ventricular hypertrophy; disarray of myocardial fibres interesting inter-ventricular septum) None (SUD) Myocarditis (inflammatory infiltrates of myocardium with degeneration and/or necrosis of the adjacent myocytes) None (SUD) HCM (symmetrical left ventricular hypertrophy; disarray of myocardial fibres interesting inter-ventricular septum) None (SUD)
© 2016 Italian Federation of Cardiology. All rights reserved.
Study of sudden cardiac death in Brescia (Italy) Vassalini et al. 449
Table 2 (continued ) Case
Sex
Age
Race
Circumstantial data
Heart weight
LV thickness
42
M
23
Caucasian
Sudden death at rest
430 g
1 cm
43
M
35
Caucasian
350 g
1.2 cm
Caucasian Caucasian
Death during work (warehouse worker) Death not witnessed Death during sleep
44 45
F M
15 36
275 g 480 g
1 cm 1 cm
46
M
27
Caucasian
Sudden death at rest
340 g
1 cm
47
M
17
Mongoloid
Death during sleep
300 g
1.2 cm
48 49
F M
28 36
Caucasian Caucasian
Sudden death at rest Sudden death at rest
280 g 320 g
1 cm 1.4 cm
50
M
17
Caucasian
500 g
1.5 cm
51
M
24
Caucasian
Death during sport activity (playing ‘Tamburello’ match) Death not witnessed
400 g
1.4 cm
52
M
25
Caucasian
Death during sleep
600 g
–
53 54
M M
33 30
Caucasian Negroid
Sudden death at rest Death not witnessed
350 g 320 g
1 cm 1.5 cm
Pathology findings CAD (atherosclerotic plaques of the coronary tree; extensive areas of fibrosis in many left and right ventricular tissue) CCS abnormalities (erythrocytic infiltration and necrosis of the NAV fibres) None (SUD) CCS abnormalities (atrio-ventricular node fetal marked dispersion and His bundle fragmentation with adipose insulation) CCS abnormalities (atrio-ventricular node fetal marked dispersion and His bundle fragmentation with adipose insulation) CCS abnormalities (localized inflammatory infiltration involving the tract penetrating bundle of His) None (SUD) Myocarditis (inflammatory infiltrates of myocardium with degeneration and/or necrosis of the adjacent myocytes) ARVC [macroscopic abnormalities of right ventricular wall (thinned, yellowish in colour, decrease of the muscular component); diffuse fibro-fatty replacement of the myocardium] CAD (right coronary ostium splitting and widespread interstitial fibrosis of the ventricular myocardium) Mitral valve prolapse (increased leaflet thickness floppiness and redundancy of mitral valve with 5 cm of diameter; myxomatous changes at histologic examination) CAD [significant narrowing (>80%) of left main artery] CCS abnormalities (atrio-ventricular node fetal marked dispersion and His bundle fragmentation with adipose insulation)
ARVC, arrhythmogenic right ventricular cardiomyopathy; CAD, coronary artery disease; CCS, cardiac conduction system; HCM, hypertrophic cardiomyopathy; LV, left ventricular; SUD, sudden unexplained death.
9 years, with documented persistence of an inter-atrial communication – ostium secundum type – associated with ventricular hypertrophy. Arrhythmogenic right ventricular dysplasia was the second most frequent finding (11.1%, n ¼ 6) among the cases with structural heart disease. Three of these cases had macroscopic abnormalities of the right ventricular wall (thinned, yellowish in colour, decrease of the muscular component), confirmed by histological evidence of diffuse fatty or fibro-fatty replacement of the myocardium (Fig. 2). Careful microscopic evaluation of the right
ventricle showed segmental areas of fibro adipose replacement in the remaining three cases. Cardiac hypertrophy was the morphological substrate in five cases (9.2%). In only three of these cases, a disarray of the myocardial fibres was found and it involved the interventricular septum. A total of four cases (7.4%) showed histopathological evidence of severe valve disease. Miyxomatous changes with a mitral valve prolapse were found in two cases and a mitral valve stenosis was found in the remaining two cases.
Fig. 1
Fig. 2
Significant eccentric narrowing of the vasal lumen of the left anterior descending artery in a 30-year-old young patient (EE 25).
Diffuse fibro-fatty replacement of myocardium in a 17-year-old adolescent (Azan 25).
© 2016 Italian Federation of Cardiology. All rights reserved.
450 Journal of Cardiovascular Medicine 2016, Vol 17 No 6
Fig. 3
absence of abnormalities of inflammatory origin charged to the common myocardium, was found. Finally, in 12 cases (22.2%), it was not possible to find any pathogenetic substrate which could explain SCD by the common diagnostic investigations, including histological evaluation of myocardial and the study of conduction tissue. These 12 cases should therefore be classified as sudden unexplained deaths (SUDs).
Discussion
Inflammatory infiltrates of myocardium with degeneration of the adjacent myocytes in a 16-year-old adolescent with apparently normal heart at gross examination (EE 25).
Myocarditis represented a non-negligible cause of SCD in our study as it was shown in four cases (7.4%, all males, aged between 15 and 38 years; Fig. 3). Serial study of the CCS showed the presence of pathological changes in 12 cases (22.2%), with macroscopic and microscopic findings apparently negative. Five cases, aged between 27 and 38 years, had signs of atrio-ventricular node fetal marked dispersion and His bundle fragmentation with adipose insulation (Fig. 4). Another pathologic substrate consisted of silent atrio-ventricular accessory pathways in four cases and atrio-ventricular node erythrocytic infiltration in the other two cases (Fig. 5). In one case – a young Chinese boy aged 17 years – localized inflammatory infiltration involving the tract penetrating the bundle of His, (Fig. 6) in the
A wide spectrum of histomorphological cardiac abnormalities can cause SCD in young patients. A correct diagnostic formulation is not possible in these cases without a detailed macroscopic and microscopic evaluation of the heart, including the ‘histological mapping’ of the ventricular myocardium (left, right and septum) and the serial study of the coronary vessels, as well as the examination of the cardiac conduction tissue. Many studies have focused on SCD, selecting patients with heterogeneous demographic characteristics. The definition of sudden death is also not uniform both by chronological criteria and by the inclusion or not of patients with known previous diseases.18 Even if several articles, book chapters and guidelines have described how pathologists should investigate SCD,7 the lack of a standardized approach makes it difficult to provide comparative studies on histomorphological findings. Through the application of a detailed procedural protocol, one of our many findings is the presence of ischaemic alterations (18.5%), mostly of a chronic nature, in our cases. Previous studies have underlined higher incidences of sudden deaths in the young adult population due to coronary event, mostly of thrombotic origin, with percentages ranging between 48 and 73%.19–23 This Fig. 5
Fig. 4
Persistence of His bundle fragmentation in a 27-year-old man with apparently normal heart at gross examination (Azan 25).
Silent atrio-ventricular accessory pathway in a 24-year-old woman with apparently normal heart at gross examination (EE 25).
© 2016 Italian Federation of Cardiology. All rights reserved.
Study of sudden cardiac death in Brescia (Italy) Vassalini et al. 451
Fig. 6
Myocarditis, most often of viral origin, is an insidious pathogenic entity characterized by a wide variability of clinical and morphological expression: it is a major cause of SCD in children and young adults.31,32 Although a high percentage of myocarditis, accounting for 20% of SCD in people under 40 years of age, has been reported in some studies,33 the prevalence of myocarditis (7.4%) in our study is in agreement with previous autopsy series showing percentages ranging from 1 to 10%.29,34,35
Localized inflammatory infiltration involving the tract penetrating the bundle of His in a 17-year-old Chinese adolescent with apparently normal heart at gross examination (Azan 25).
discrepancy can be explained by the different diagnostic criteria used in sample selection: only patients aged under 40 years without a suggestive clinical history for the presence of a cardiac pathology were included in our study. It is noteworthy that no case with acute abnormalities of the coronary arteries was found in our study. In agreement with the previous studies,24 sudden cardiac arrest as the first symptom of a congenital heart disease is a rare event. This is adequately explained by the current ability of an early diagnosis of these diseases so that only in a few cases is the diagnosis by paediatric observation missed. According to other reports in adolescents and young adults, cardiomyopathies are the most frequent causes of SCD10,25: we observed arrhythmogenic right ventricular cardiomyopathy (ARVC) in 11.1% of the cases and myocardial hypertrophy in 9.2%. The incidence of ARVC is in line with those reported by Basso et al.26 in studies performed in northern Italy, resulting, however, greater than in studies performed in North Europe and North America.27,28 Findings of hypertrophic cardiomyopathy in our study are consistent with those reported by previous surveys in the young adult population.29,30 We found a disarray of the myocardial fibres, interesting specifically the interventricular septum, in only three of these five cases.
It is necessary to underline the need for a careful histological evaluation of the myocardium. The so-called ‘Dallas criteria’, proposed in 1986, are of limited use in forensic application because they were formulated for endomyocardial biopsy, not autopsy, diagnosis.36 A correct post mortem approach presents considerable difficulties of interpretation.37,38 Some authors pointed out the possibility of an overestimation in the histological diagnosis of myocarditis: focal inflammatory infiltrates, also with marked myocytolysis, may represent an incidental finding at autopsy in patients who died from violent causes.36,39 In order to have a correct diagnostic classification, Casali et al.40 proposed a routine application of a careful histological mapping from the whole heart (analysis of at least 20 slides in the authors’ opinion) and a careful anamnestic investigation for an appropriate integration of anatomo-pathological findings. Other authors also underlined the necessity of combined investigations using histopathology, molecular and pathological techniques, and immunohistochemistry to reveal the causal agents of SCD.41 In our series, 24 of the 54 cases (44.4%) had no pathological abnormalities at gross and routinary histological investigation. In 22.2% of these inconclusive cases, the examination of the CCS disclosed pathological changes. Although many simplified methods of the CCS analysis have been proposed,42,43 an accurate evaluation of findings needs a laborious and expensive procedure that should be carried out with caution because unspecific (fibro-fatty infiltration) and ageing-related changes (calcification, fibro-fatty, etc.) may be common.44 The CCS anatomical variability and the lack of experience in sampling techniques and in learning about the CCS, together with different interpretations of results given by the authors, make a correct evaluation of each histomorphological finding more difficult.45 Persistent fetal dispersion of the atrio-ventricular node and marked fragmentation of the His bundle were observed in five cases of this study. The pathogenetic role of this finding is not clear. Some authors postulated that fetal dispersion and/or His fragmentation can be a normal congenital variation also present in control cases46; according to other studies, instead, this finding may represent an anatomic substrate for deceleration in the stimulus conduction at the intra-Hisian level and may
© 2016 Italian Federation of Cardiology. All rights reserved.
452 Journal of Cardiovascular Medicine 2016, Vol 17 No 6
permit the phenomenon of re-entry or produce abnormal automaticity or block due to the splitting of the impulse transmission.47,48
2
In our study, the percentage of cases characterized by CCS abnormalities (22%) is greatly influenced by the inclusion of such specific histomorphological findings in this sample, and differ with data previously reported.49 In the absence of a significant pathogenetic substrate, in these SCD cases of young people, it was decided not to exclude a possible role of such alteration in the hypothesis of an arrhythmic fatal event. However, in the absence of scientific evidence, it is necessary that adequate information be given to the family members, indicating further cardiologic checks in patients who are alive.
4
Minor interpretative problems are associated with the detection of silent atrio-ventricular accessory pathways (present in 4 of the 54 cases) or haemorrhagic/inflammatory infiltration of the cardiac conduction tissue.44,50,51
10
In many cases, sudden death in young people remains unexplained after a complete autopsy and after an accurate conduction system analysis: like previous studies,52,53 SUD is frequent in our study (22.2% of autopsied sudden death cases). This high number of SUDs can be explained by the strict application of the major diagnostic criteria relative to the main histomorphological alterations, with particular reference to the arrhythmogenic cardiomyopathy of the right ventricle, the hypertrophic cardiomyopathy and the myocarditis. In conclusion, this study underlines the importance of an accurate autopsy study, performed according to standardized protocols, in SCD cases.7,54 Despite difficulties and disagreement on the significance of non-specific findings or normal variants, our study showed that conduction system examination can provide useful information in the identification of the pathological substrate determining an arrhythmic event. A systematic autoptic examination of the heart and the conduction system study is only the initial step of a process aimed not only to the formulation of a diagnostic judgment but also to prevent possible fatal cardiac events in the surviving relatives of the victims.8 The forensic activity does not end in the search for a cause of death, but it must provide detailed information for family members, directing them towards the appropriate cardiologic screening.55 The molecular diagnostic investigations in such selected cases are extremely useful, not only for diagnostic purposes but also for adopting proper therapeutic and preventive strategies among the family members.
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Priori SG, Aliot E, Blomstrom-Lundqvist C, et al. Task force on sudden cardiac death of the European Society of Cardiology. Eur Heart J 2001; 22:1374–1450. Chugh SS, Kelley KL, Titus JL. Sudden cardiac death with apparently normal heart. Circulation 2000; 102:649–654. Myeburg RJ, Castellanos A. Cardiac arrest and sudden cardiac death. In: Braunwald E, editor. Heart disease: a textbook of cardiovascular, medicine, 5th ed Philadelphia, PA: WB Saunders; 1997. pp. 742–779. Puranik R, Chow CK, Duflou JA, et al. Sudden death in the young. Heart Rhythm 2005; 2:1277–1282. Vaartjes I, Hendrix A, Hertogh EM, et al. Sudden death in person younger than 40 years of age: incidence and cause. Eur J Cardiovasc Prevent Rehabil 2009; 16:592–596. Oliva A, Brugada R, D’Aloja E, et al. State of the art in forensic investigation of sudden cardiac death. Am J Forensic Med Pathol 2011; 32:1–16. Di Gioia CRT, Autore C, Romeo DM, et al. Sudden cardiac death in younger adults: autopsy diagnosis as a tool for preventive medicine. Human Pathol 2006; 37:794–801. Bharati S. Pathology of the conduction system. In: Silver MD, Gotlieb AI, Schoen FJ, editors. Cardiovascular pathology, 3rd ed New York: Churchill Livingstone; 2001. Corrado D, Basso C, Poletti A, et al. Sudden death in the young: is coronary thrombosis the major precipitating factor? Circulation 1994; 90:2315– 2323. Silver MD, Silver MM. Valvular heart disease: conditions causing regurgitation. In: Silver MD, Gotlieb AI, Schoen FJ, editors. Cradiovascular pathology, 3rd ed Philadelphia: Churchill Livingstone; 2011. pp. 443–470. Maron BJ, Epstein SE. Hypertrophic cardiomyopathy: a discussion of nomenclature. Am J Cardiol 1979; 43:1242–1244. Davies MJ, McKenna WJ. Hypertrophic cardiomyopathy: pathology and pathogenesis. Histopathology 1995; 26:493–500. Marcus FI, Fontaine GH, Guiraudon G, et al. Right ventricular dysplasia: a report of 24 adult cases. Circulation 1982; 65:384–398. Basso C, Thiene G, Corrado D, et al. Arrhytmogenic right ventricular cardiomyopathy: dysplasia, dystrophy or myocarditis? Circulation 1996; 94:983–991. Tabib A, Loire R, Chalabreyesse L, et al. Circumstances of death and gross and miscroscopic observations in a series of 200 cases of sudden death associated with arrhytmogenic right ventricular cardiomyopathy and/or dysplasia. Circulation 2003; 108:3000–3005. Aretz HT. Myocarditis: the Dallas criteria. Hum Pathol 1987; 18:619–624. Morentin B, Aguilera B, Garamendi PM, Suarez-Mier MP. Sudden unexpected nonviolent death between 1 and 19 years in north Spain. Arch Dis Child 2000; 82:456–461. Davies MJ. The investigation of sudden cardiac death. Histopathology 1999; 34:93–98. Leach IH, Blundell JW, Rowley JM, et al. Acute ischaemic lesions in death due to ischaemic heart disease: an autopsy study of 333 out of hospital deaths. Eur Heart J 1995; 16:1181–1185. Burke AP, Farb A, Malcolm GT, et al. Coronary risk factor and plaque morphology in men with coronary disease who died suddenly. N Engl J Med 1997; 336:1276–1282. Arzamendi D, Benito B, Tizon-Marcos H, et al. Increase in sudden death from coronary artery disease in young adults. Am Heart J 2011; 161:574– 580. Shen WK, Edwards Wd, Hammill SC, et al. Sudden unexpected non traumatic death in 54 young adults: a 30-year population-based study. Am J Cardiol 1995; 76:148–152. Cecchi R, Picca D, Cipolloni L. La morte improvvisa nel settorato dell’Istituto di Medicina Legale di Roma «La Sapienza» nel decennio 1985– 1995. Riv It Med Leg 2000; 22:493–515. Maron BJ, Shirani J, Poliac LC, et al. Sudden death in young competitive athletes. Clinical, demographic and pathological profiles. J Am Med Assoc 1996; 276:199–204. Basso D, Corrado D, Thiene G. Cardiovascular causes of sudden death in young individuals, including athletes. Cardiol Rev 1999; 7:127–135. Winkel BG, Holst AG, Theilade J, et al. Nationwide study of sudden cardiac death in person aged 1–35 years. Eur Heart J 2011; 32:983–990. Virmani R, Burke AP, Farb A. Sudden cardiac death. Cardiovasc Pathol 2001; 10:211–218. Corrado D, Basso C, Thiene G. Sudden cardiac death in young people with apparently normal heart. Cardiovasc Res 2001; 50:399–408. Eckart RE, Shry EA, Burke AP, et al. Sudden death in young adults. An autopsy-based series of a population undergoing active surveillance. J Am Coll Cardiol 2011; 58:1254–1261. Steinberger J, Lucas RV, Edwards JE, Titus JL. Cause of sudden unexpected cardiac death in the first two decades of life. Am J Cardiol 1996; 77:992–995.
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32 33 34 35
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Kyto¨ V, Saukko P, Lignitz E, et al. Diagnosis and presentation of fatal myocarditis. Hum Pathol 2005; 36:1003–1007. McCaffrey FM, Braden DS, Strong WB. Sudden cardiac death in young athletes: a review. Am J Dis Child 1991; 145:177–183. Gore I, Shapir O. Myocarditis: a classification of 1402 cases. Am Heart J Pathol 1947; 34:827–830. Luke JL, Helpern M. Sudden unexplained death from natural cause in young adults: a review of 275 consecutive autopsied cases. Am J Pathol 1968; 85:10–17. Zhang M, Tavora F, Zhang Y, et al. The role of focal myocardial inflammation in sudden unexpected cardiac and noncardiac deaths: a clinicopathological study. Int J Leg Med 2013; 127:131–138. Baughman KL. Diagnosis of myocarditis: death of Dallas criteria. Circulation 2006; 113:593–595. Peters NS, Poole-Wilson PA. Myocarditis-continuing clinical and pathological confusion. Am Heart J 1991; 121:942–947. Claydon SM. Myocarditis as incidental findings in young men dying from unnatural causes. Med Sci Law 1989; 29:55–58. Casali MB, Lazzaro A, Gentile G, et al. Forensic grading of myocarditis: an experimental contribution to the distinction between lethal myocarditis and incidental myocarditis. Forensic Sci Int 2012; 223: 78–86. Gaaloul I, Riabi S, Harrath R, et al. Sudden unexpected death related to enterovirus myocarditis: histopathology, immunohistochemistry and molecular pathology diagnosis at postmortem. BMC Infect Dis 2012; 12:212–218. Michaud K, Romain N, Taroni F, et al. Evaluation of a simplified method of the conduction system analysis in 110 cases. Forensic Sci Int 2002; 130:13–24. Song Y, Zhu J, Laaksonen H, Saukko P. A modified method for examining the cardiac conduction system. Forensic Sci Int 1997; 86:135–138.
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Haring G, Kralj E, Balazˇic J, Ermenec B. Diagnostic value of postmortem examination of the cardiac conduction system. For Sci Int Suppl Ser 2009; 1:72–75. De la Grandmaison GL. Is there progress in the autopsy diagnosis of sudden unexpected death in adults? Forensic Sci Int 2006; 156:138–144. Suarez-Mier MP, Gamallo C. Atrioventricular node fetal dispersion and his bundle fragmentation of the cardiac conduction system in sudden cardiac death. J Am Coll Cardiol 1998; 32:1885–1890. Bharati S, Lev M. Congenital abnormalities of the conduction system in sudden death in young adults. J Am Coll Cardiol 1986; 8:1096–1104. Ottaviani G, Matturri L, Rossi L, James TN. Crib death: further support for the concept of fatal cardiac electrical instability as the final common pathway. Int J Cardiol 2003; 92:17–26. Chole SD, Suarez-Mier PM, Aguilera B. Sudden death resulting from lesions of the cardiac conduction system. Am J Forensic Med Pathol 2002; 23:83–89. Gulino SP. Examination of the cardiac conduction system. Forensic application in cases of sudden cardiac death. Am J Forenisc Med Pathol 2003; 24:227–238. Nishida N, Ikeda N, Kudo K, et al. Forensic significance of conduction system abnormalities as a precise cause of accidental death. Int J Legal Med 2002; 116:344–349. Morentin B, Sua´rez-Mier MP, Aguilera B. Sudden unexplained death among persons 1–35 years old. Forensic Sci Int 2003; 135:213–217. Winkel BG. Sudden cardiac death in young Danes. Dan Med J 2012; 59:B4403. Basso C, Burke M, Fornes P, et al. Guidelines for autopsy investigation of sudden cardiac death. Virchows Arch 2008; 452:11–18. Ackerman MJ, Priori SG, Willems S, et al. HRS/EHRA expert consensus statement on the state of genetic testing for the channelopathies and cardiomyopathies. Europace 2011; 13:1077–1109.
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An autopsy study of sudden cardiac death in persons aged 1–40 years in Brescia (Italy) Marzia Vassalini, Andrea Verzeletti, Mario Restori and Francesco De Ferrari Introduction Sudden cardiac death (SCD), above all when occurring in young people, remains a major clinical problem. We have analysed the clinical and post mortem findings of patients who were evaluated for SCD.
12 cases (22.2%), in whom the heart was structurally normal at macroscopic examination. Despite all the investigations carried out, any pathogenic substrate that could have justified death was not found in 12 cases (22.2%).
Methods and results We have analysed 54 cases of SCD which occurred in patients aged below 40 years during the period 1993–2012 and were studied at the Institute of Forensic Medicine of Brescia. The following variables were considered: sex, age, medical history, autopsy findings with special reference to macroscopic and histological evaluation of the heart and toxicological investigation. In all cases, we also performed the dissection of the cardiac conduction tissue with subsequent serial sampling and careful microscopic evaluation.
Conclusion Our study underlines the value of an accurate routine post mortem investigation that may show an otherwise unsuspected structural heart disease. The serial study of the conduction tissue may provide pathologic substrates that may be responsible for the arrhythmic cause of death. A meaningful percentage of cases (22%) had no evidence of any abnormality. Genetic testing can be indicated in these cases.
Most SCD patients were men (76%), with a mean age of 27 years. The results of post mortem investigations have identified the following abnormalities: coronary artery disease (18.5%), arrhythmogenic right ventricular dysplasia (11.1%), hypertrophic obstructive cardiomyopathy (9.2%), severe valvular heart disease (7.4%) and myocarditis (7.4%). A case of persistence of the inter-atrial communication with cardiomegaly and right and left ventricular hypertrophy was also reported. Examination of the cardiac conduction tissue showed abnormalities in
Introduction Sudden unexpected death in young people is a rare event, but when it occurs, it is always tragic and of concern for families and physicians. Despite advances in the screening and the diagnosis of cardiovascular disease, sudden cardiac death (SCD) is often the first manifestation of an underlying heart problem in apparently healthy individuals. The incidence of SCD is not uniform depending on many factors such as sex, age, ethnic group, chronological criteria and methodology of diagnosis. A task force of the European Society of Cardiology has indicated that the incidence ranges from 36 to 128 deaths per 100 000 people per year.1,2 In the majority of the patients with a cardiac arrest, a structural or functional abnormality can be identified through routine post mortem investigations.3 Several authors examined morphological findings in SCD case studies: the relative importance of different causes of the fatal outcome varies among studies, coronary artery disease (CAD) being the most common.4 1558-2027 ß 2016 Italian Federation of Cardiology. All rights reserved.
J Cardiovasc Med 2016, 17:446–453 Keywords: conduction tissue, histological findings, molecular diagnosis, sudden cardiac death Department of Medical and Surgical Specialties, Radiological Sciences and Public Health, Section of Public Health and Human Sciences, Forensic Medicine Unit, University of Brescia, Brescia, Italy Correspondence to Marzia Vassalini, Istituto di Medicina Legale, Universita` degli Studi di Brescia, Piazzale Spedali Civili 1, 25123 Brescia, Italy Tel: +39 0303995480; fax: +39 0303995839; e-mail: [email protected] Received 27 May 2014 Revised 28 September 2014 Accepted 30 September 2014
A careful autopsy and an accurate gross and microscopic heart examination are necessary to formulate a correct diagnosis. The aim of this study is to describe the clinical and post mortem findings of patients who died suddenly and were evaluated at the Institute of Forensic Medicine of Brescia. All the patients were studied using strict standardized criteria including the microscopic examination of the cardiac conduction system (CCS).
Material and methods For the purpose of this study, we have analysed all the SCD cases which occurred between January 1993 and December 2012 in patients aged 1–40 years. Cases of sudden infant death syndromes (under 1 year of age) were ruled out. SCD is defined as an unexpected natural death that occurs instantaneously or within 24 h of the onset of symptoms or collapse,5,6 with autopsy exclusion of extracardiac causes and drug or alcohol abuse upon the post mortem toxicologic screening of blood and urine. DOI:10.2459/JCM.0000000000000234
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Study of sudden cardiac death in Brescia (Italy) Vassalini et al. 447
For each death, the following data were collected: sex, age, circumstances of witnessed deaths, family history and retrospective clinical information. After excluding cases with a positive history of heart disease and cases of drug intoxication, a complete gross and histological study, including CCS, and toxicology were performed. After fixation in 10% buffered formaldehyde, the morphology of the heart was evaluated: heart weight, chamber size, wall thickness, longitudinal, transverse and antero-posterior diameters, endocardium and valve devices, coronary arteries (by taking transverse sections at 4-mm intervals), as well as myocardium and epicardial fat distribution. In agreement with the standards reported in the literature,7,8 multiple samples for histology were taken from three standard sites (anterior, lateral and posterior) of both ventricles and of the inter-ventricular septum, as well as sample from coronary walls (when affected by the presence of atherosclerotic plaques or thrombotic phenomena) and from lesions observed at gross examination. The study of the CCS was carried out by dissection into two blocks9: one obtained in order to study the sinusatrial node (SAN) and the other block excised for the examination of the atrio-ventricular junction (AVN) and its artery (His bundle and bundle branches). The blocks were processed through standard steps (an alcohol 95 washing, four 1,4-dioxane steps and one 1,4-dioxaneparaffin step); afterwards, they were embedded in paraffin and completely sectioned (5-mm serial section, with 20–30-mm intervals). The histological preparations were coloured with haematoxylin–eosin and trichrome Azan. In order to better evaluate the myofibres and arteriolar elastic fibres, Walsh and Weigert’s method was also used. Post mortem diagnosis was based on the criteria summarized in Table 1.10–17 Table 1
Results From the review of autopsy and external examination reports, we identified 54 SCD cases, accounting for 0.7% of the 7804 post mortem examinations conducted by the Institute of Forensic Medicine of Brescia over the 20-year study period (Table 2). There was a male predominance: 41 males (76%) and 13 females (24%). The median (inter-quartile range) age of the SCD population was 27 (22.25, 32.75) years, with an age range of 9–39 years. With respect to the clinical circumstances at the time of the SCD event, symptoms onset was during, or immediately before, physical activity (sport or work) in 12 cases (22.2%). Death occurred during sleep in eight cases (14.8%). Post mortem investigations have identified ischaemic abnormalities in 10 cases (18.5%) (Fig. 1): in 4 of these cases, there was a severe coronary disease with a concentric or eccentric stenosis of the vasal lumen greater than 70%, associated with ‘acute’ ischaemic abnormalities of the myocardium (erythrocytes infiltration, coagulation necrosis of the myocytes) (Fig. 1). Areas of myocardial sclerosis with moderate-grade coronary artery stenosis (40–50%) were found in the remaining six cases. A case of a young man aged 24 years, with autoptic finding of an anatomic abnormality of the coronary origin (right coronary ostium splitting), associated with the widespread presence of minute areas of interstitial fibrosis of the ventricular myocardium, was reported. In our study, the absence of SCD cases resulting from thrombotic events, plaque rupture or dissection of the coronary arteries should be taken into account. The average age of patients with CAD was equal to 31 years, with prevalence of male sex (seven cases) compared with that of females (two cases). With respect to the presence of congenital heart defects, we report only one case concerning a male patient, aged
Morphological findings in SCD cases
Diagnosis
Pathological abnormalities
Coronary artery disease (CAD)
Significant narrowing 70% of the cross-sectional coronary artery diameters, with signs of atherosclerosis, thrombosis, fibrous plaque fissuring or rupture and dissection10 Atrial septal defect (sinus venosus type, ostium primum type, ostium secundum type), inter-ventricular septal defect, Botallo’s persistent ductus arteriosus, aortic coarctation, tricuspid atresia and anomalies of origin of the coronary vases Thickening, fibrosis, deformation, retraction or myxomatous degeneration of the valve leaflets with a consequent stenosis or insufficiency of severe entity11 Asymmetrical or symmetrical left ventricular hypertrophy. Myocardial hypertrophy in the absence of any other cardiac or systemic disease that could cause it, with histological finding of extensive myofibre disarray12,13 Trans-mural fibrous and fatty myocardial replacement, either right ventricular or biventricular, associated with myofibre regressive changes in at least two sites of the ‘triangle of dysplasia’ (infundibulum, postero-basal right ventricular wall, anterior wall)14–16 Inflammatory infiltrates of myocardium with degeneration and/or necrosis of the adjacent myocytes17 Cardiac conduction system (CCS) abnormalities Absence of any abnormality at gross and histological analysis of the heart well as the examination of the cardiac conduction tissue
Congenital heart disease
Valve disease Hypertrophic cardiomyopathy (HCM)
Arrhytmogenic right ventricular cardiomyopathy (ARVC) Myocarditis ‘Apparently normal heart’ Sudden unexplained death (SUD)
© 2016 Italian Federation of Cardiology. All rights reserved.
448 Journal of Cardiovascular Medicine 2016, Vol 17 No 6
Table 2 Case
Demographic, clinical and autoptic data Sex
Age
Race
Circumstantial data
Heart weight
LV thickness
1
F
27
Caucasian
Death not witnessed
250 g
1 cm
2
F
29
Caucasian
Sudden death at rest
343 g
1.5 cm
3
M
29
Caucasian
Death during sport activity (football)
420 g
1.5 cm
4
M
26
Caucasian
Sudden death at rest (in a pub)
520 g
2.5 cm
5
M
22
Caucasian
383 g
1.2 cm
6
M
9
Caucasian
Death during sport activity (football) Death during sleep
180 g
1.5 cm
7 8
M M
25 27
Caucasian Caucasian
9
M
19
10 11
M M
12 13 14
Pathology findings CAD and myocardial sclerosis (atherosclerotic plaques of the left anterior descending coronary with narrowing equal to 50%; extensive areas of fibrosis in many left ventricular tissue) Mitral valve prolapse (increased leaflet thickness floppiness and redundancy of mitral valve; myxomatous changes) CAD and myocardial sclerosis (atherosclerotic plaques of three coronary vessels without significant narrowing; extensive areas of fibrosis in many left and right ventricular tissue) Mitral and aortic valve stenosis [parietal endocardium, mitral and aortic cusps markedly thickened with severe valve stenosis; coronary atherosclerotic plaques (maximum narrowing of 60%); disarray of myocardial fibres] CCS abnormalities (atrio-ventricular node erythrocytic infiltration; fibro-muscular hyperplasia of the AVN artery) Congenital heart disease (persistence of inter-atrial communication, ostium secundum type) HCM (symmetrical left ventricular hypertrophy) CCS abnormalities (atrio-ventricular node fetal marked dispersion and His bundle fragmentation with adipose insulation) Mitral valve stenosis (mitral cusps markedly thickened with severe valve stenosis) None (SUD) CAD [atherosclerotic plaques of three vessels (maximum narrowing of 60%); contraction band necrosis] HCM (symmetrical left ventricular hypertrophy) None (SUD) Mitral valve prolapse (increased leaflet thickness floppiness and redundancy of mitral valve; myxomatous changes) CAD [significant narrowing (>80%)of left main coronary; narrowing (40%) of left circumflex; anomalous insertion of the medial flap of the tricuspid] CCS abnormalities (silent atrio-ventricular accessory pathway) CAD [significant narrowing (90%) of left anterior descending artery; coagulation necrosis of the myocytes] ARVC (diffuse fibro-fatty replacement of the right wall)
480 g 354 g
3.2 cm 1.3 cm
Caucasian
Death not witnessed Death during work (metal worker) Sudden death at rest
363 g
2.7 cm
34 37
Caucasian Caucasian
Sudden death at rest Sudden death at rest
420 g 400 g
1.6 cm 1.7 cm
F F M
23 27 26
Caucasian Caucasian Caucasian
Death not witnessed Sudden death at rest Sudden death at rest
350 g 330 g 400 g
2.5 cm 1.3 cm 1.5 cm
15
M
39
Caucasian
Death during work (home builder)
300 g
1.5 cm
16 17
F M
22 30
Caucasian Caucasian
Sudden death at rest Death not witnessed
250 g 230 g
1 cm 1.5 cm
18
F
13
Caucasian
260 g
1 cm
19 20 21 22 23
F F F M M
35 24 28 34 20
Caucasian Caucasian Caucasian Negroid Caucasian
400 g 280 g 240 g 336 g 280 g
1.3 cm 1.2 cm 1.5 cm 2 cm 1.4 cm
ARVC (diffuse fatty replacement of the right wall) CCS abnormalities (silent atrio-ventricular accessory pathway) None (SUD) CCS abnormalities (silent atrio-ventricular accessory pathway) CCS abnormalities (silent atrio-ventricular accessory pathway)
24
M
38
Negroid
Death during sport activity (swimming) Sudden death at rest Sudden death at rest Death during sleep Sudden death at rest Death during sport activity (running) Death not witnessed
350 g
1.3 cm
25
M
15
Caucasian
Death during physical activity (at school)
250 g
1 cm
26
M
27
Caucasian
413 g
1.6 cm
27
M
31
Caucasian
Death during not specified work Sudden death at rest
Myocarditis (inflammatory infiltrates of myocardium with degeneration and/or necrosis of the adjacent myocytes) Myocarditis (inflammatory infiltrates of myocardium with degeneration and/or necrosis of the adjacent myocytes. Immunohistochemistry: CD4R0 positive; microbiological analyses: negative) None (SUD)
530 g
3 cm
28 29
F M
25 31
Caucasian Caucasian
Sudden death at rest Death not witnessed
260 g 420 g
1.1 cm 2.4 cm
30 31
M M
27 16
Caucasian Caucasian
Sudden death at rest Death not witnessed
435 g 350 g
1.5 cm 1 cm
32 33
M M
20 35
Caucasian Caucasian
Death not witnessed Death not witnessed
515 g 410 g
1.7 cm 1.7 cm
34
M
14
Caucasian
240 g
1 cm
35
M
26
Caucasian
450 g
1.8 cm
ARVC (segmental areas of fibro adipose replacement)
36 37 38 39
M M M M
29 32 35 17
Caucasian Indian Caucasian Caucasian
454 g 340 g 409 g 308 g
1.5 cm 1.3 cm 1.5 cm 1 cm
None (SUD) ARVC (segmental areas of fibro adipose replacement) ARVC (segmental areas of fibro adipose replacement) None (SUD)
40
F
38
Caucasian
Death during work (farmer) Death during sport activity (football) Death during sleep Sudden death at rest Death during sleep Death during sport activity (running) Sudden death at rest
400 g
1.6 cm
41
M
38
Caucasian
Death during sleep
450 g
1.7 cm
CAD (atherosclerotic plaques of the coronary tree; extensive areas of fibrosis in many left ventricular tissue) CCS abnormalities (atrio-ventricular node fetal marked dispersion and His bundle fragmentation with adipose insulation)
HCM (symmetrical left ventricular hypertrophy; disarray of myocardial fibres interesting inter-ventricular septum) None (SUD) HCM (symmetrical left ventricular hypertrophy; disarray of myocardial fibres interesting inter-ventricular septum) None (SUD) Myocarditis (inflammatory infiltrates of myocardium with degeneration and/or necrosis of the adjacent myocytes) None (SUD) HCM (symmetrical left ventricular hypertrophy; disarray of myocardial fibres interesting inter-ventricular septum) None (SUD)
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Study of sudden cardiac death in Brescia (Italy) Vassalini et al. 449
Table 2 (continued ) Case
Sex
Age
Race
Circumstantial data
Heart weight
LV thickness
42
M
23
Caucasian
Sudden death at rest
430 g
1 cm
43
M
35
Caucasian
350 g
1.2 cm
Caucasian Caucasian
Death during work (warehouse worker) Death not witnessed Death during sleep
44 45
F M
15 36
275 g 480 g
1 cm 1 cm
46
M
27
Caucasian
Sudden death at rest
340 g
1 cm
47
M
17
Mongoloid
Death during sleep
300 g
1.2 cm
48 49
F M
28 36
Caucasian Caucasian
Sudden death at rest Sudden death at rest
280 g 320 g
1 cm 1.4 cm
50
M
17
Caucasian
500 g
1.5 cm
51
M
24
Caucasian
Death during sport activity (playing ‘Tamburello’ match) Death not witnessed
400 g
1.4 cm
52
M
25
Caucasian
Death during sleep
600 g
–
53 54
M M
33 30
Caucasian Negroid
Sudden death at rest Death not witnessed
350 g 320 g
1 cm 1.5 cm
Pathology findings CAD (atherosclerotic plaques of the coronary tree; extensive areas of fibrosis in many left and right ventricular tissue) CCS abnormalities (erythrocytic infiltration and necrosis of the NAV fibres) None (SUD) CCS abnormalities (atrio-ventricular node fetal marked dispersion and His bundle fragmentation with adipose insulation) CCS abnormalities (atrio-ventricular node fetal marked dispersion and His bundle fragmentation with adipose insulation) CCS abnormalities (localized inflammatory infiltration involving the tract penetrating bundle of His) None (SUD) Myocarditis (inflammatory infiltrates of myocardium with degeneration and/or necrosis of the adjacent myocytes) ARVC [macroscopic abnormalities of right ventricular wall (thinned, yellowish in colour, decrease of the muscular component); diffuse fibro-fatty replacement of the myocardium] CAD (right coronary ostium splitting and widespread interstitial fibrosis of the ventricular myocardium) Mitral valve prolapse (increased leaflet thickness floppiness and redundancy of mitral valve with 5 cm of diameter; myxomatous changes at histologic examination) CAD [significant narrowing (>80%) of left main artery] CCS abnormalities (atrio-ventricular node fetal marked dispersion and His bundle fragmentation with adipose insulation)
ARVC, arrhythmogenic right ventricular cardiomyopathy; CAD, coronary artery disease; CCS, cardiac conduction system; HCM, hypertrophic cardiomyopathy; LV, left ventricular; SUD, sudden unexplained death.
9 years, with documented persistence of an inter-atrial communication – ostium secundum type – associated with ventricular hypertrophy. Arrhythmogenic right ventricular dysplasia was the second most frequent finding (11.1%, n ¼ 6) among the cases with structural heart disease. Three of these cases had macroscopic abnormalities of the right ventricular wall (thinned, yellowish in colour, decrease of the muscular component), confirmed by histological evidence of diffuse fatty or fibro-fatty replacement of the myocardium (Fig. 2). Careful microscopic evaluation of the right
ventricle showed segmental areas of fibro adipose replacement in the remaining three cases. Cardiac hypertrophy was the morphological substrate in five cases (9.2%). In only three of these cases, a disarray of the myocardial fibres was found and it involved the interventricular septum. A total of four cases (7.4%) showed histopathological evidence of severe valve disease. Miyxomatous changes with a mitral valve prolapse were found in two cases and a mitral valve stenosis was found in the remaining two cases.
Fig. 1
Fig. 2
Significant eccentric narrowing of the vasal lumen of the left anterior descending artery in a 30-year-old young patient (EE 25).
Diffuse fibro-fatty replacement of myocardium in a 17-year-old adolescent (Azan 25).
© 2016 Italian Federation of Cardiology. All rights reserved.
450 Journal of Cardiovascular Medicine 2016, Vol 17 No 6
Fig. 3
absence of abnormalities of inflammatory origin charged to the common myocardium, was found. Finally, in 12 cases (22.2%), it was not possible to find any pathogenetic substrate which could explain SCD by the common diagnostic investigations, including histological evaluation of myocardial and the study of conduction tissue. These 12 cases should therefore be classified as sudden unexplained deaths (SUDs).
Discussion
Inflammatory infiltrates of myocardium with degeneration of the adjacent myocytes in a 16-year-old adolescent with apparently normal heart at gross examination (EE 25).
Myocarditis represented a non-negligible cause of SCD in our study as it was shown in four cases (7.4%, all males, aged between 15 and 38 years; Fig. 3). Serial study of the CCS showed the presence of pathological changes in 12 cases (22.2%), with macroscopic and microscopic findings apparently negative. Five cases, aged between 27 and 38 years, had signs of atrio-ventricular node fetal marked dispersion and His bundle fragmentation with adipose insulation (Fig. 4). Another pathologic substrate consisted of silent atrio-ventricular accessory pathways in four cases and atrio-ventricular node erythrocytic infiltration in the other two cases (Fig. 5). In one case – a young Chinese boy aged 17 years – localized inflammatory infiltration involving the tract penetrating the bundle of His, (Fig. 6) in the
A wide spectrum of histomorphological cardiac abnormalities can cause SCD in young patients. A correct diagnostic formulation is not possible in these cases without a detailed macroscopic and microscopic evaluation of the heart, including the ‘histological mapping’ of the ventricular myocardium (left, right and septum) and the serial study of the coronary vessels, as well as the examination of the cardiac conduction tissue. Many studies have focused on SCD, selecting patients with heterogeneous demographic characteristics. The definition of sudden death is also not uniform both by chronological criteria and by the inclusion or not of patients with known previous diseases.18 Even if several articles, book chapters and guidelines have described how pathologists should investigate SCD,7 the lack of a standardized approach makes it difficult to provide comparative studies on histomorphological findings. Through the application of a detailed procedural protocol, one of our many findings is the presence of ischaemic alterations (18.5%), mostly of a chronic nature, in our cases. Previous studies have underlined higher incidences of sudden deaths in the young adult population due to coronary event, mostly of thrombotic origin, with percentages ranging between 48 and 73%.19–23 This Fig. 5
Fig. 4
Persistence of His bundle fragmentation in a 27-year-old man with apparently normal heart at gross examination (Azan 25).
Silent atrio-ventricular accessory pathway in a 24-year-old woman with apparently normal heart at gross examination (EE 25).
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Study of sudden cardiac death in Brescia (Italy) Vassalini et al. 451
Fig. 6
Myocarditis, most often of viral origin, is an insidious pathogenic entity characterized by a wide variability of clinical and morphological expression: it is a major cause of SCD in children and young adults.31,32 Although a high percentage of myocarditis, accounting for 20% of SCD in people under 40 years of age, has been reported in some studies,33 the prevalence of myocarditis (7.4%) in our study is in agreement with previous autopsy series showing percentages ranging from 1 to 10%.29,34,35
Localized inflammatory infiltration involving the tract penetrating the bundle of His in a 17-year-old Chinese adolescent with apparently normal heart at gross examination (Azan 25).
discrepancy can be explained by the different diagnostic criteria used in sample selection: only patients aged under 40 years without a suggestive clinical history for the presence of a cardiac pathology were included in our study. It is noteworthy that no case with acute abnormalities of the coronary arteries was found in our study. In agreement with the previous studies,24 sudden cardiac arrest as the first symptom of a congenital heart disease is a rare event. This is adequately explained by the current ability of an early diagnosis of these diseases so that only in a few cases is the diagnosis by paediatric observation missed. According to other reports in adolescents and young adults, cardiomyopathies are the most frequent causes of SCD10,25: we observed arrhythmogenic right ventricular cardiomyopathy (ARVC) in 11.1% of the cases and myocardial hypertrophy in 9.2%. The incidence of ARVC is in line with those reported by Basso et al.26 in studies performed in northern Italy, resulting, however, greater than in studies performed in North Europe and North America.27,28 Findings of hypertrophic cardiomyopathy in our study are consistent with those reported by previous surveys in the young adult population.29,30 We found a disarray of the myocardial fibres, interesting specifically the interventricular septum, in only three of these five cases.
It is necessary to underline the need for a careful histological evaluation of the myocardium. The so-called ‘Dallas criteria’, proposed in 1986, are of limited use in forensic application because they were formulated for endomyocardial biopsy, not autopsy, diagnosis.36 A correct post mortem approach presents considerable difficulties of interpretation.37,38 Some authors pointed out the possibility of an overestimation in the histological diagnosis of myocarditis: focal inflammatory infiltrates, also with marked myocytolysis, may represent an incidental finding at autopsy in patients who died from violent causes.36,39 In order to have a correct diagnostic classification, Casali et al.40 proposed a routine application of a careful histological mapping from the whole heart (analysis of at least 20 slides in the authors’ opinion) and a careful anamnestic investigation for an appropriate integration of anatomo-pathological findings. Other authors also underlined the necessity of combined investigations using histopathology, molecular and pathological techniques, and immunohistochemistry to reveal the causal agents of SCD.41 In our series, 24 of the 54 cases (44.4%) had no pathological abnormalities at gross and routinary histological investigation. In 22.2% of these inconclusive cases, the examination of the CCS disclosed pathological changes. Although many simplified methods of the CCS analysis have been proposed,42,43 an accurate evaluation of findings needs a laborious and expensive procedure that should be carried out with caution because unspecific (fibro-fatty infiltration) and ageing-related changes (calcification, fibro-fatty, etc.) may be common.44 The CCS anatomical variability and the lack of experience in sampling techniques and in learning about the CCS, together with different interpretations of results given by the authors, make a correct evaluation of each histomorphological finding more difficult.45 Persistent fetal dispersion of the atrio-ventricular node and marked fragmentation of the His bundle were observed in five cases of this study. The pathogenetic role of this finding is not clear. Some authors postulated that fetal dispersion and/or His fragmentation can be a normal congenital variation also present in control cases46; according to other studies, instead, this finding may represent an anatomic substrate for deceleration in the stimulus conduction at the intra-Hisian level and may
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452 Journal of Cardiovascular Medicine 2016, Vol 17 No 6
permit the phenomenon of re-entry or produce abnormal automaticity or block due to the splitting of the impulse transmission.47,48
2
In our study, the percentage of cases characterized by CCS abnormalities (22%) is greatly influenced by the inclusion of such specific histomorphological findings in this sample, and differ with data previously reported.49 In the absence of a significant pathogenetic substrate, in these SCD cases of young people, it was decided not to exclude a possible role of such alteration in the hypothesis of an arrhythmic fatal event. However, in the absence of scientific evidence, it is necessary that adequate information be given to the family members, indicating further cardiologic checks in patients who are alive.
4
Minor interpretative problems are associated with the detection of silent atrio-ventricular accessory pathways (present in 4 of the 54 cases) or haemorrhagic/inflammatory infiltration of the cardiac conduction tissue.44,50,51
10
In many cases, sudden death in young people remains unexplained after a complete autopsy and after an accurate conduction system analysis: like previous studies,52,53 SUD is frequent in our study (22.2% of autopsied sudden death cases). This high number of SUDs can be explained by the strict application of the major diagnostic criteria relative to the main histomorphological alterations, with particular reference to the arrhythmogenic cardiomyopathy of the right ventricle, the hypertrophic cardiomyopathy and the myocarditis. In conclusion, this study underlines the importance of an accurate autopsy study, performed according to standardized protocols, in SCD cases.7,54 Despite difficulties and disagreement on the significance of non-specific findings or normal variants, our study showed that conduction system examination can provide useful information in the identification of the pathological substrate determining an arrhythmic event. A systematic autoptic examination of the heart and the conduction system study is only the initial step of a process aimed not only to the formulation of a diagnostic judgment but also to prevent possible fatal cardiac events in the surviving relatives of the victims.8 The forensic activity does not end in the search for a cause of death, but it must provide detailed information for family members, directing them towards the appropriate cardiologic screening.55 The molecular diagnostic investigations in such selected cases are extremely useful, not only for diagnostic purposes but also for adopting proper therapeutic and preventive strategies among the family members.
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