i n d i a n h e a r t j o u r n a l 6 6 ( 2 0 1 4 ) 1 8 8 e1 9 2
Available online at www.sciencedirect.com
ScienceDirect journal homepage: www.elsevier.com/locate/ihj
Original Article
Detection of paroxysmal atrial fibrillation or flutter in patients with acute ischemic stroke or transient ischemic attack by Holter monitoring Sandeep Thakkar a,*, Rajeev Bagarhatta b a b
Senior Resident, Department of Cardiology, SMS Medical College, Jaipur, Rajasthan, India Professor, Department of Cardiology, SMS Medical College, Jaipur, Rajasthan, India
article info
abstract
Article history:
Background and purpose: Paroxysmal atrial fibrillation and flutter are strong risk factors for
Received 1 April 2013
stroke. Due to high recurrence rate of ischemic events and given the benefit of oral anti-
Accepted 5 February 2014
coagulation over antiplatelet drugs, it is important to identify this arrhythmia. Unfortu-
Available online 4 March 2014
nately, paroxysmal AF or flutter is asymptomatic in majority and therefore, difficult to detect.
Keywords:
Methods: Consecutive patients presenting with symptoms of acute ischemic stroke or
Paroxysmal atrial fibrillation
transient ischemic attack were included. All patients free of AF or flutter on presentation
Atrial flutter
underwent 24 h Holter monitoring within 7 days of admission.
Acute ischemic stroke
Results: Overall, fifty two (52) patients (mean age 59.51 13.45 years) with acute stroke
Transient ischemic attack
(80.8%) and TIA (19.8%) underwent 24 h Holter monitoring. Paroxysmal AF was detected in
Holter monitoring
3 cases (5.8%), all 3 patients had acute stroke and were older than age 60 years. Type of stroke was the only factor which was associated with greater risk of having paroxysmal AF or flutter, AF accounted for 50% cases (2 out of 4) of clinically suspected cardio embolic stroke. Conclusion: Screening consecutive patients with ischemic stroke with routine Holter monitoring will identify new atrial fibrillation/flutter in approximately one in 17 patients. Older age and type of stroke are strongly associated with increased risk. By carefully selecting the patients, the detection rates could be further increased. Copyright ª 2014, Cardiological Society of India. All rights reserved.
1.
Introduction
Atrial fibrillation (AF) and flutter are strong risk factors for stroke and identifying them is an important part of the etiological work up of patients with acute ischemic stroke or
transient ischemic attack (TIA). Atrial fibrillation and flutter account for 10% of all strokes and 50% of cardio embolic strokes.1 Stroke associated with AF carries a poor prognosis as more than 50% of the survivors remain with a severe deficit, and recurrence may be as high as 12% per year.2 Treatment with warfarin and other oral anticoagulants provides a greater
* Corresponding author. c/o. Dr. Rajeev Bagarhatta, 530, Opp. Ram Mandir, Mahaveer Nagar 1, Tonk Road, Jaipur, Rajasthan 302004, India. Tel.: þ91 (0) 8094261451, þ91 (0) 1412722181. E-mail addresses: [email protected], [email protected] (S. Thakkar). 0019-4832/$ e see front matter Copyright ª 2014, Cardiological Society of India. All rights reserved. http://dx.doi.org/10.1016/j.ihj.2014.02.009
i n d i a n h e a r t j o u r n a l 6 6 ( 2 0 1 4 ) 1 8 8 e1 9 2
relative risk reduction in recurrent stroke compared with antiplatelet therapy3; therefore it is important to identify this arrhythmia. Unfortunately, AF remains under diagnosed as it is often asymptomatic with up to 30% of patients unaware of their diagnosis,4 moreover paroxysmal atrial fibrillation is intermittent and has been reported to be asymptomatic in up to 90% of the patients, therefore it is difficult to detect.5,6 However, the risk of thromboembolism purported by atrial fibrillation is same whether paroxysmal or permanent.7 Because of poor sensitivity of single standard ECG for detection of paroxysmal AF, 24 h Holter study is a better option, allowing the detection of previously unrecognized AF. Also the probability of detecting atrial fibrillation may be higher in the acute phase due to clustering of episodes of the arrhythmia,8,9 making early initiation of monitoring advantageous. In this study we examined feasibility and detection rates of atrial fibrillation with 24 h Holter monitoring applied early (within 7 days of admission) in patients presenting with acute stroke or transient ischemic attack (TIA).
2.
Material and methods
We enrolled 52 patients admitted with a diagnosis of acute stroke or TIA to the Neurology and Medicine Department of S.M.S Hospital, Jaipur, India. Patients with previously diagnosed persistent or paroxysmal AF, primary hemorrhagic stroke, acute large vessel dissection or inability or refusal of consent were excluded from the study. Baseline characteristics were recorded including a detailed medical history and major risk factors. All patients underwent detailed neurological examination, standard laboratory tests, extra cranial carotid duplex ultrasonography, transthoracic echocardiography and a neuroimaging study (cerebral CT scan or cerebral MRI or both).
3.
Electrographic studies
All patients had a standard 12-lead ECG at admission. Additional ECG was performed if any arrhythmia was suspected on clinical grounds. In absence of any evidence of AF, the patients were recruited into the study group and after written informed consent, a 24 h 12 channel Holter (H-SCRIBE, Mortara instruments, Inc. Milwaukee USA.) monitor was applied within 7 days of symptom onset by specifically trained medical staff and monitors were collected for analysis after 24 h. Electrographic recordings were later on analyzed offline with a focus on detecting atrial fibrillation or flutter. Heart rate and RR variability plots were checked for patterns suggestive of atrial fibrillation. Supraventricular premature complexes, supraventricular tachycardia, ventricular premature complexes and ventricular tachycardia as detected by the automated software algorithm were scanned. Electrographic strips representing fastest and slowest heart rates were also inspected and intensive manual review was also undertaken for most of the cases.10 Results of the Holter study were communicated to respective treating physicians and any change of therapy was solely left to the discretion of treating physician.
4.
189
Definitions and statistical analysis
Etiology of the stroke was classified according to Trial of org in Acute Stroke Treatment (TOAST) classification scheme.11 Transient ischemic attack was defined as sudden, focal neurological deficit of presumed vascular origin lasting less than 24 h. Presence of atrial fibrillation was defined as at least 1 period of >30 s duration. Episodes of frequent supraventricular ectopy (>10 supraventricular complexes in a row) were also recorded. Discrete categorical data were presented as n (%); Normality of quantitative data was checked by measures of Kolmogorov Smirnov tests of normality. Continuous data were given as mean SD, range or as median and interquartile range as appropriate. ManneWhitney U-test was used for statistical analysis of continuous variables. For categorical data comparisons were made by Pearson Chi-square test or Fisher’s exact test as appropriate. All statistical tests were two-sided and performed at a significance level of a ¼ 0.05. Analysis was conducted using SPSS for Windows (version 15.0; SPSS Inc., Chicago, IL, USA).
5.
Results
Total 52 patients of acute stroke or transient ischemic attack (TIA) were finally enrolled in our study after ruling out those with exclusion criteria. 42 (80.8%) had acute ischemic stroke and 10 (19.2%) had TIA. Baseline clinical characteristics are summarized in Table 1. All patients had their Holter monitoring initiated within 7 days of admission. In 31 cases (59.6%) it was started on day 2 of admission, in 17 cases (32.7%) on day 3 and in remaining 4 cases (4.7%) on day 4. Routine transthoracic echocardiogram was done in all cases, 8 patients (15.4%) had evidence of left ventricular hypertrophy (LVH) and one patient had severe left ventricular dysfunction secondary to old myocardial infarction. In our study we found 3 cases (5.8%) of paroxysmal AF among 52 patients. All patients had acute ischemic stroke, and were older in age (Table 2). One patient had single episode of AF of 4 min duration while other 2 cases had multiple episodes lasting several seconds to few minutes (Fig. 1). None of the patients reported any symptoms during the recording period. Neither prior history of stroke or TIA, nor prior history of palpitations was associated with greater risk of having paroxysmal AF or flutter. Only factor which was found to be significantly associated with risk of AF or flutter was the type of stroke, AF was present among 2 out of 4 cases of suspected cardio embolic stroke on the basis of clinical presentation and neuroimaging data.
6.
Discussion
In the present study, paroxysmal AF was detected in 3 (5.8%) cases, beyond that was detected by physical examination and initial electrocardiogram on presentation, thus identifying AF in approximately one in 17 patients. Detection rates are similar to those reported by earlier studies (3.9%e5.5%).12,13 Importantly paroxysmal AF accounted for 50% (2 out of 4) of
190
i n d i a n h e a r t j o u r n a l 6 6 ( 2 0 1 4 ) 1 8 8 e1 9 2
Table 1 e Patient characteristics (n [ 52). 59.51 13.45 years
Age Sex Male Female TIA Stroke Toast classification Cardioembolic Large vessel Lacunar Undetermined History of stroke History of TIA History of palpitations Diabetes Hypertension Smoking Coronary artery disease Echo LVH LV Dysfunction
40 12 10 42
(76.9%) (23.1%) (19.2%) (80.8%)
4 (9.5%) 17 (40.47%) 5 (11.90%) 16 (38.10%) 4 (7.7%) 10 (19.2%) 15 (28.8%) 12 (23.1%) 27 (51.9%) 28 (53.8%) 8 (15.4%) 8 (15.4%) 1 (1.7%)
our cases with suspected cardio embolic stroke while none of patients with lacunar stroke had AF. However, because of small number of patients enrolled, this study is underpowered to make definite conclusions about relation of paroxysmal AF with regards to lacunar stroke but similar findings were also observed in studies done by Jabaudon et al14 and Stahrenberg et al,10 in which no cases of new AF were seen in patients with lacunar stroke. By excluding such patients, including the ones with suspected cardio embolic stroke and those with some underlying risk factors for cardiovascular disease, we expect the yield could be further increased.
Table 2 e Comparison of patients with or without atrial fibrillation. AF present (n ¼ 3) Age Sex Male Female TIA Stroke Toast classification Cardioembolic Large vessel Lacunar Undetermined History of stroke History of TIA History of palpitations Diabetes Hypertension Smoking Coronary artery disease Echo LVH LV Dysfunction LVEF
AF absent (n ¼ 49)
p Value
70.67 10.01 years
58.86 13.26 years
NS
3 0 0 3
(100%) (0.0%) (0.0%) (100.0%)
12 (41.3%) 37 (58.7%) 10 (38.77%) 39 (61.23%)
NS
2 0 0 1 0 1 2 1 2 3 1
(66.67%) (0.0%) (0.0%) (33.33%) (0.0%) (33.33%) (66.67%) (33.33%) (66.67%) (100.00%) (33.33%)
2 (5.13%) 17 (43.59%) 5 (12.82%) 15 (38.46%) 4 (8.16%) 2 (4.08%) 13(26.53%) 11 (22.45%) 25 (51.02%) 25 (51.02%) 7 (14.28%)
P ¼ 0.03
1 (33.33%) 0 (0.0%)
7 14.29%) 1 (2.08%)
NS
58.33 5.77%
56.51 4.56%
NS NS
NS NS NS NS NS NS NS
American heart and stroke association (AHA/ASA) recommends that all patients with acute cerebral ischemia should undergo cardiovascular evaluation including monitoring of cardiac rhythm on telemetry or by Holter monitoring for detection of atrial fibrillation or other serious arrhythmias, both for determination of the cause of the stroke and to optimize immediate and long-term management, but still Holter monitoring remains an underutilized investigation in routine clinical practice in our country. Interestingly all patients of acute stroke undergo routine carotid Doppler on admission in most institutions and detection rate reported in literature for carotid ultrasound in acute stroke is about 7.9%.15 Therefore, we expect that by carefully selecting the patients undergoing Holter, its yield can be increased to match that of carotid ultrasound study. Because recurrence of stroke in AF is 3e5% in first few weeks after initial event16,17 and up to 12% in untreated patients in first two to three years3,18 and since oral anticoagulation significantly reduces the risk of recurrent stroke and systemic embolism in patients with persistent or paroxysmal AF as compared to aspirin (1.5 vs. 4.7 events per 100 patient years),19 it is important to identify this arrhythmia. Now with the advent of new generation of novel oral anticoagulants which do not have any monitoring issues, treatment of these patients will become easier with significant relative risk reduction for secondary ischemic events. The ideal timing and duration of monitoring is an issue which still remains unresolved. Increased duration of monitoring has been reported to be associated with increased detection rates. In the 2 studies that evaluated event loop recorders (ELR) new AF was detected in 5.7% and 7.7% cases respectively.13,14 In a study by Stahrenberg et al10 which evaluated early and prolonged 7 day continuous Holter monitoring, new AF was detected in 12.5% of cases. In their study Holter monitoring was initiated on day of admission in the emergency department itself and detection rates for every single day were evaluated and they found that there was no significant pattern favoring any given period or day, and importantly there was no evidence for a higher detection on day 1. Thus starting monitoring very early may not be that much crucial, however a very prolonged delay between symptom onset and Holter monitoring may render causal relationship between arrhythmia and stroke debatable. Jabaudon et al14 evaluated the use of both Holter and ELR (for Holter negative patients) for detection of paroxysmal AF and in their study number needed to screen (NNS) values for both were comparable (18 vs. 20); therefore authors suggested that stepwise sequential workup should be followed. In our opinion also, this is a better approach since wearing ELR or a prolonged 7 day Holter monitor is cumbersome, the analysis is time consuming and it delays the results, therefore it is better to start with Holter first and those patients who are Holter negative but have high risk of paroxysmal arrhythmias be subjected to prolonged monitoring.
7.
Study limitations
Sample size of our study was small, which is a clear limitation of this study. Second, only hospitalized patients were included
i n d i a n h e a r t j o u r n a l 6 6 ( 2 0 1 4 ) 1 8 8 e1 9 2
191
Fig. 1 e Holter tracing of a patient with acute ischemic stroke shows run of paroxysmal AF.
so our findings cannot be extrapolated to outpatient stroke population. Thirdly, change in therapy was left to the discretion of treating physician and those patients were not prospectively followed for occurrence of recurrent events.
8.
Conclusions
In conclusion, screening patients with acute ischemic stroke or TIA will identify new paroxysmal AF or flutter in approximately one in 17 patients with normal standard ECG. By confining its use to selected patient population, its diagnostic yield may be further increased. Given the benefit of oral anticoagulation in this setting Holter monitoring will allow introduction of appropriate treatment and better secondary prevention.
4.
5.
6.
7.
8.
Conflicts of interest All authors have none to declare.
references
1. Hart RG. Stroke prevention in atrial fibrillation. Curr Cardiol Rep. 2000;2:51e55. 2. Mattle HP. Long-term outcome after stroke due to atrial fibrillation. Cerebrovasc Dis. 2003;16:3e8. 3. European Atrial Fibrillation Trial (EAFT) Study Group. Secondary prevention in non-rheumatic atrial fibrillation
9.
10.
11.
after transient ischemic attack or minor stroke. Lancet. 1993;342:1255e1262. Furberg CD, Psaty BM, Manolio TA, Gardin JM, Smith VE, Rautaharju PM. Prevalence of atrial fibrillation in elderly subjects (the Cardiovascular Health Study). Am J Cardiol. 1994;74:236e241. Israel CW, Gro¨nefeld G, Ehrlich JR, Li YG, Hohnloser SH. Longterm risk of recurrent atrial fibrillation as documented by an implantable monitoring device: implications for optimal patient care. J Am Coll Cardiol. 2004;43:47e52. Page RL, Wilkinson WE, Clair WK, McCarthy EA, Pritchett EL. Asymptomatic arrhythmias in patients with symptomatic paroxysmal atrial fibrillation and paroxysmal supraventricular tachycardia. Circulation. 1994;89:224e227. Hohnloser SH, Pajitnev D, Pogue J, et al. Incidence of stroke in paroxysmal versus sustained atrial fibrillation in patients taking oral anticoagulation or combined antiplatelet therapy: an ACTIVE W substudy. J Am Coll Cardiol. 2007;50:2156e2161. Kirchhof P, Auricchio A, Bax J, et al. Outcome parameters for trials in atrial fibrillation: recommendations from a consensus conference organized by the German Atrial Fibrillation Competence NETwork and the European Heart Rhythm Association. Europace. 2007;9:1006e1023. Gillis AM, Rose MS. Temporal patterns of paroxysmal atrial fibrillation following DDDR pacemaker implantation. Am J Cardiol. 2000;85:1445e1450. Stahrenberg R, Kruger MW, Seegers J, et al. Enhanced detection of paroxysmal atrial fibrillation by early and prolonged continuous Holter monitoring in patients with cerebral ischemia presenting in sinus rhythm. Stroke. 2010;41:2884e2888. Adams Jr HP, Bendixen BH, Kappelle LJ, et al. Classification of subtype of acute ischemic stroke. Definitions for use in a multicenter clinical trial. TOAST. Trial of Org 10172 in Acute Stroke Treatment. Stroke. 1993;24:35e41.
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12. Rem JA, Hachinski VC, Boughner DR, Barnett HJ. Value of cardiac monitoring and echocardiography in TIA and stroke patients. Stroke. 1985;16:950e956. 13. Barthelemy JC, Feasson-Gerard S, Garnier P, et al. Automatic cardiac event recorders reveal paroxysmal atrial fibrillation after unexplained strokes or transient ischemic attacks. Ann Noninvasive Electrocardiol. 2003;8:194e199. 14. Jabaudon D, Sztajzel J, Sievert K, Landis T, Sztajzel R. Usefulness of ambulatory 7-day ECG monitoring for the detection of atrial fibrillation and flutter after acute stroke and transient ischemic attack. Stroke. 2004;35: 1647e1651. 15. Yu EH, Lungu C, Kanner RM, Libman RB. The use of diagnostic tests in patients with acute ischemic stroke. J Stroke Cerebrovasc Dis. 2009;18:178e184.
16. The International Stroke Trial (IST): a randomised trial of aspirin, subcutaneous heparin, both, or neither among 19435 patients with acute ischaemic stroke. International Stroke Trial Collaborative Group. Lancet. 1997;349:1569e1581. 17. Saxena R, Lewis S, Berge E, Sandercock PA, Koudstaal PJ. Risk of early death and recurrent stroke and effect of heparin in 3169 patients with acute ischemic stroke and atrial fibrillation in the International Stroke Trial. Stroke. 2001;32:2333e2337. 18. Sandercock P, Bamford J, Dennis M, et al. Atrial fibrillation and stroke: prevalence in different types of stroke and influence on early and long term prognosis (Oxfordshire community stroke project). BMJ. 1992;305:1460e1465. 19. Van Walraven C, Hart RG, Singer DE, et al. Oral anticoagulants vs aspirin in nonvalvular atrial fibrillation: an individual patient meta-analysis. JAMA. 2002;288:2441e2448.
Available online at www.sciencedirect.com
ScienceDirect journal homepage: www.elsevier.com/locate/ihj
Original Article
Detection of paroxysmal atrial fibrillation or flutter in patients with acute ischemic stroke or transient ischemic attack by Holter monitoring Sandeep Thakkar a,*, Rajeev Bagarhatta b a b
Senior Resident, Department of Cardiology, SMS Medical College, Jaipur, Rajasthan, India Professor, Department of Cardiology, SMS Medical College, Jaipur, Rajasthan, India
article info
abstract
Article history:
Background and purpose: Paroxysmal atrial fibrillation and flutter are strong risk factors for
Received 1 April 2013
stroke. Due to high recurrence rate of ischemic events and given the benefit of oral anti-
Accepted 5 February 2014
coagulation over antiplatelet drugs, it is important to identify this arrhythmia. Unfortu-
Available online 4 March 2014
nately, paroxysmal AF or flutter is asymptomatic in majority and therefore, difficult to detect.
Keywords:
Methods: Consecutive patients presenting with symptoms of acute ischemic stroke or
Paroxysmal atrial fibrillation
transient ischemic attack were included. All patients free of AF or flutter on presentation
Atrial flutter
underwent 24 h Holter monitoring within 7 days of admission.
Acute ischemic stroke
Results: Overall, fifty two (52) patients (mean age 59.51 13.45 years) with acute stroke
Transient ischemic attack
(80.8%) and TIA (19.8%) underwent 24 h Holter monitoring. Paroxysmal AF was detected in
Holter monitoring
3 cases (5.8%), all 3 patients had acute stroke and were older than age 60 years. Type of stroke was the only factor which was associated with greater risk of having paroxysmal AF or flutter, AF accounted for 50% cases (2 out of 4) of clinically suspected cardio embolic stroke. Conclusion: Screening consecutive patients with ischemic stroke with routine Holter monitoring will identify new atrial fibrillation/flutter in approximately one in 17 patients. Older age and type of stroke are strongly associated with increased risk. By carefully selecting the patients, the detection rates could be further increased. Copyright ª 2014, Cardiological Society of India. All rights reserved.
1.
Introduction
Atrial fibrillation (AF) and flutter are strong risk factors for stroke and identifying them is an important part of the etiological work up of patients with acute ischemic stroke or
transient ischemic attack (TIA). Atrial fibrillation and flutter account for 10% of all strokes and 50% of cardio embolic strokes.1 Stroke associated with AF carries a poor prognosis as more than 50% of the survivors remain with a severe deficit, and recurrence may be as high as 12% per year.2 Treatment with warfarin and other oral anticoagulants provides a greater
* Corresponding author. c/o. Dr. Rajeev Bagarhatta, 530, Opp. Ram Mandir, Mahaveer Nagar 1, Tonk Road, Jaipur, Rajasthan 302004, India. Tel.: þ91 (0) 8094261451, þ91 (0) 1412722181. E-mail addresses: [email protected], [email protected] (S. Thakkar). 0019-4832/$ e see front matter Copyright ª 2014, Cardiological Society of India. All rights reserved. http://dx.doi.org/10.1016/j.ihj.2014.02.009
i n d i a n h e a r t j o u r n a l 6 6 ( 2 0 1 4 ) 1 8 8 e1 9 2
relative risk reduction in recurrent stroke compared with antiplatelet therapy3; therefore it is important to identify this arrhythmia. Unfortunately, AF remains under diagnosed as it is often asymptomatic with up to 30% of patients unaware of their diagnosis,4 moreover paroxysmal atrial fibrillation is intermittent and has been reported to be asymptomatic in up to 90% of the patients, therefore it is difficult to detect.5,6 However, the risk of thromboembolism purported by atrial fibrillation is same whether paroxysmal or permanent.7 Because of poor sensitivity of single standard ECG for detection of paroxysmal AF, 24 h Holter study is a better option, allowing the detection of previously unrecognized AF. Also the probability of detecting atrial fibrillation may be higher in the acute phase due to clustering of episodes of the arrhythmia,8,9 making early initiation of monitoring advantageous. In this study we examined feasibility and detection rates of atrial fibrillation with 24 h Holter monitoring applied early (within 7 days of admission) in patients presenting with acute stroke or transient ischemic attack (TIA).
2.
Material and methods
We enrolled 52 patients admitted with a diagnosis of acute stroke or TIA to the Neurology and Medicine Department of S.M.S Hospital, Jaipur, India. Patients with previously diagnosed persistent or paroxysmal AF, primary hemorrhagic stroke, acute large vessel dissection or inability or refusal of consent were excluded from the study. Baseline characteristics were recorded including a detailed medical history and major risk factors. All patients underwent detailed neurological examination, standard laboratory tests, extra cranial carotid duplex ultrasonography, transthoracic echocardiography and a neuroimaging study (cerebral CT scan or cerebral MRI or both).
3.
Electrographic studies
All patients had a standard 12-lead ECG at admission. Additional ECG was performed if any arrhythmia was suspected on clinical grounds. In absence of any evidence of AF, the patients were recruited into the study group and after written informed consent, a 24 h 12 channel Holter (H-SCRIBE, Mortara instruments, Inc. Milwaukee USA.) monitor was applied within 7 days of symptom onset by specifically trained medical staff and monitors were collected for analysis after 24 h. Electrographic recordings were later on analyzed offline with a focus on detecting atrial fibrillation or flutter. Heart rate and RR variability plots were checked for patterns suggestive of atrial fibrillation. Supraventricular premature complexes, supraventricular tachycardia, ventricular premature complexes and ventricular tachycardia as detected by the automated software algorithm were scanned. Electrographic strips representing fastest and slowest heart rates were also inspected and intensive manual review was also undertaken for most of the cases.10 Results of the Holter study were communicated to respective treating physicians and any change of therapy was solely left to the discretion of treating physician.
4.
189
Definitions and statistical analysis
Etiology of the stroke was classified according to Trial of org in Acute Stroke Treatment (TOAST) classification scheme.11 Transient ischemic attack was defined as sudden, focal neurological deficit of presumed vascular origin lasting less than 24 h. Presence of atrial fibrillation was defined as at least 1 period of >30 s duration. Episodes of frequent supraventricular ectopy (>10 supraventricular complexes in a row) were also recorded. Discrete categorical data were presented as n (%); Normality of quantitative data was checked by measures of Kolmogorov Smirnov tests of normality. Continuous data were given as mean SD, range or as median and interquartile range as appropriate. ManneWhitney U-test was used for statistical analysis of continuous variables. For categorical data comparisons were made by Pearson Chi-square test or Fisher’s exact test as appropriate. All statistical tests were two-sided and performed at a significance level of a ¼ 0.05. Analysis was conducted using SPSS for Windows (version 15.0; SPSS Inc., Chicago, IL, USA).
5.
Results
Total 52 patients of acute stroke or transient ischemic attack (TIA) were finally enrolled in our study after ruling out those with exclusion criteria. 42 (80.8%) had acute ischemic stroke and 10 (19.2%) had TIA. Baseline clinical characteristics are summarized in Table 1. All patients had their Holter monitoring initiated within 7 days of admission. In 31 cases (59.6%) it was started on day 2 of admission, in 17 cases (32.7%) on day 3 and in remaining 4 cases (4.7%) on day 4. Routine transthoracic echocardiogram was done in all cases, 8 patients (15.4%) had evidence of left ventricular hypertrophy (LVH) and one patient had severe left ventricular dysfunction secondary to old myocardial infarction. In our study we found 3 cases (5.8%) of paroxysmal AF among 52 patients. All patients had acute ischemic stroke, and were older in age (Table 2). One patient had single episode of AF of 4 min duration while other 2 cases had multiple episodes lasting several seconds to few minutes (Fig. 1). None of the patients reported any symptoms during the recording period. Neither prior history of stroke or TIA, nor prior history of palpitations was associated with greater risk of having paroxysmal AF or flutter. Only factor which was found to be significantly associated with risk of AF or flutter was the type of stroke, AF was present among 2 out of 4 cases of suspected cardio embolic stroke on the basis of clinical presentation and neuroimaging data.
6.
Discussion
In the present study, paroxysmal AF was detected in 3 (5.8%) cases, beyond that was detected by physical examination and initial electrocardiogram on presentation, thus identifying AF in approximately one in 17 patients. Detection rates are similar to those reported by earlier studies (3.9%e5.5%).12,13 Importantly paroxysmal AF accounted for 50% (2 out of 4) of
190
i n d i a n h e a r t j o u r n a l 6 6 ( 2 0 1 4 ) 1 8 8 e1 9 2
Table 1 e Patient characteristics (n [ 52). 59.51 13.45 years
Age Sex Male Female TIA Stroke Toast classification Cardioembolic Large vessel Lacunar Undetermined History of stroke History of TIA History of palpitations Diabetes Hypertension Smoking Coronary artery disease Echo LVH LV Dysfunction
40 12 10 42
(76.9%) (23.1%) (19.2%) (80.8%)
4 (9.5%) 17 (40.47%) 5 (11.90%) 16 (38.10%) 4 (7.7%) 10 (19.2%) 15 (28.8%) 12 (23.1%) 27 (51.9%) 28 (53.8%) 8 (15.4%) 8 (15.4%) 1 (1.7%)
our cases with suspected cardio embolic stroke while none of patients with lacunar stroke had AF. However, because of small number of patients enrolled, this study is underpowered to make definite conclusions about relation of paroxysmal AF with regards to lacunar stroke but similar findings were also observed in studies done by Jabaudon et al14 and Stahrenberg et al,10 in which no cases of new AF were seen in patients with lacunar stroke. By excluding such patients, including the ones with suspected cardio embolic stroke and those with some underlying risk factors for cardiovascular disease, we expect the yield could be further increased.
Table 2 e Comparison of patients with or without atrial fibrillation. AF present (n ¼ 3) Age Sex Male Female TIA Stroke Toast classification Cardioembolic Large vessel Lacunar Undetermined History of stroke History of TIA History of palpitations Diabetes Hypertension Smoking Coronary artery disease Echo LVH LV Dysfunction LVEF
AF absent (n ¼ 49)
p Value
70.67 10.01 years
58.86 13.26 years
NS
3 0 0 3
(100%) (0.0%) (0.0%) (100.0%)
12 (41.3%) 37 (58.7%) 10 (38.77%) 39 (61.23%)
NS
2 0 0 1 0 1 2 1 2 3 1
(66.67%) (0.0%) (0.0%) (33.33%) (0.0%) (33.33%) (66.67%) (33.33%) (66.67%) (100.00%) (33.33%)
2 (5.13%) 17 (43.59%) 5 (12.82%) 15 (38.46%) 4 (8.16%) 2 (4.08%) 13(26.53%) 11 (22.45%) 25 (51.02%) 25 (51.02%) 7 (14.28%)
P ¼ 0.03
1 (33.33%) 0 (0.0%)
7 14.29%) 1 (2.08%)
NS
58.33 5.77%
56.51 4.56%
NS NS
NS NS NS NS NS NS NS
American heart and stroke association (AHA/ASA) recommends that all patients with acute cerebral ischemia should undergo cardiovascular evaluation including monitoring of cardiac rhythm on telemetry or by Holter monitoring for detection of atrial fibrillation or other serious arrhythmias, both for determination of the cause of the stroke and to optimize immediate and long-term management, but still Holter monitoring remains an underutilized investigation in routine clinical practice in our country. Interestingly all patients of acute stroke undergo routine carotid Doppler on admission in most institutions and detection rate reported in literature for carotid ultrasound in acute stroke is about 7.9%.15 Therefore, we expect that by carefully selecting the patients undergoing Holter, its yield can be increased to match that of carotid ultrasound study. Because recurrence of stroke in AF is 3e5% in first few weeks after initial event16,17 and up to 12% in untreated patients in first two to three years3,18 and since oral anticoagulation significantly reduces the risk of recurrent stroke and systemic embolism in patients with persistent or paroxysmal AF as compared to aspirin (1.5 vs. 4.7 events per 100 patient years),19 it is important to identify this arrhythmia. Now with the advent of new generation of novel oral anticoagulants which do not have any monitoring issues, treatment of these patients will become easier with significant relative risk reduction for secondary ischemic events. The ideal timing and duration of monitoring is an issue which still remains unresolved. Increased duration of monitoring has been reported to be associated with increased detection rates. In the 2 studies that evaluated event loop recorders (ELR) new AF was detected in 5.7% and 7.7% cases respectively.13,14 In a study by Stahrenberg et al10 which evaluated early and prolonged 7 day continuous Holter monitoring, new AF was detected in 12.5% of cases. In their study Holter monitoring was initiated on day of admission in the emergency department itself and detection rates for every single day were evaluated and they found that there was no significant pattern favoring any given period or day, and importantly there was no evidence for a higher detection on day 1. Thus starting monitoring very early may not be that much crucial, however a very prolonged delay between symptom onset and Holter monitoring may render causal relationship between arrhythmia and stroke debatable. Jabaudon et al14 evaluated the use of both Holter and ELR (for Holter negative patients) for detection of paroxysmal AF and in their study number needed to screen (NNS) values for both were comparable (18 vs. 20); therefore authors suggested that stepwise sequential workup should be followed. In our opinion also, this is a better approach since wearing ELR or a prolonged 7 day Holter monitor is cumbersome, the analysis is time consuming and it delays the results, therefore it is better to start with Holter first and those patients who are Holter negative but have high risk of paroxysmal arrhythmias be subjected to prolonged monitoring.
7.
Study limitations
Sample size of our study was small, which is a clear limitation of this study. Second, only hospitalized patients were included
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Fig. 1 e Holter tracing of a patient with acute ischemic stroke shows run of paroxysmal AF.
so our findings cannot be extrapolated to outpatient stroke population. Thirdly, change in therapy was left to the discretion of treating physician and those patients were not prospectively followed for occurrence of recurrent events.
8.
Conclusions
In conclusion, screening patients with acute ischemic stroke or TIA will identify new paroxysmal AF or flutter in approximately one in 17 patients with normal standard ECG. By confining its use to selected patient population, its diagnostic yield may be further increased. Given the benefit of oral anticoagulation in this setting Holter monitoring will allow introduction of appropriate treatment and better secondary prevention.
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Conflicts of interest All authors have none to declare.
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