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Durability of Homografts Used to Treat Complex Aortic Valve Endocarditis Willem Flameng, MD, PhD, Willem Daenen, MD, Ramadan Jashari, MD, Paul Herijgers, MD, PhD, and Bart Meuris, MD, PhD Department of Cardiac Surgery, KU Leuven, University Hospitals Leuven, Leuven, and European Homograft Bank, Brussels, Belgium
Background. Acute bacterial endocarditis may be extremely destructive for cardiac valves and their periannular structures. It has been suggested that complex reconstruction procedures require the use of homografts because of their versatility and potency to resist repeated infection. Methods. We studied the long-term results of 69 patients with complex endocarditis who received homografts in the aortic position. Results. The results after a mean follow-up of 8.1 ± 5.1 years (median, 8.0 years) showed that the recurrence of
endocarditis even in these complex cases is low (7%), but the incidence of structural valve degeneration (SVD) is high. Freedom from SVD at 10 years is only 60.0%. When aortic homografts degenerate, they predominantly calcify. Conclusions. The use of homografts to reconstruct endocarditis-related aortic valve destruction is associated with a low recurrence of endocarditis but a high incidence of SVD in the long run.
I
Material and Methods
n the literature, the use of a homograft as treatment for acute aortic endocarditis has been associated with a lower incidence of recurrence of endocarditis than has the use of a prosthetic valve [1]. Therefore the homograft has been advocated as the first choice to replace an infected valve [2]. In contrast, from long-term studies in nonendocarditis valve pathologic conditions, we have learned that homografts are prone to structural valve degeneration (SVD), mainly in younger patients [3, 4]. Even in elderly patients, significantly more valve degeneration and a higher need for reoperation has been reported after aortic root replacement with a homograft than after the use of a Freestyle bioprosthesis (Medtronic Inc, Minneapolis, MN) [5]. Specifically in the setting of acute bacterial endocarditis, long-term durability of homografts has never been systematically studied. Also, whenever the durability of homografts implanted for endocarditis has occasionally been reported, it was regarding the need for reoperation and not based on echocardiographic criteria of valve function. It can be shown in previous reports that the reoperation rate significantly underestimates the rate of SVD [6]. In the present study, we describe the long-term results of 69 patients undergoing aortic valve replacement for acute complex bacterial endocarditis. Besides mortality, reoperation rates, and recurrence of endocarditis, the development of SVD based on serial echocardiography is reported.
Accepted for publication Nov 3, 2014. Address correspondence to Dr Meuris, Department of Cardiac Surgery, UZ Gasthuisberg, Herestraat 49, B-3000 Leuven, Belgium; e-mail: bart. [email protected].
Ó 2015 by The Society of Thoracic Surgeons Published by Elsevier
(Ann Thorac Surg 2015;99:1234–8) Ó 2015 by The Society of Thoracic Surgeons
The study was approved by the Ethical Committee of the University Hospitals Leuven (Belgium), and the need for individual patient consent was waived.
Homografts Cryopreserved homografts were provided by the European Homograft Bank and processed as described previously [7]. Sixty-six aortic and 3 pulmonary homografts were used. In most cases, aortic root homografts had the anterior mitral valve leaflet preserved during graft procurement. This allowed the closure of subannular defects in extensive aortic root destruction as well as simultaneous replacement of the entire recipient anterior mitral leaflet together with aortic root replacement (surgical details are described further on).
Patient Population and Valve Pathologic Processes A total of 69 patients were operated on for congestive heart failure caused by severe valve insufficiency eventually combined with septic systemic embolization. All characteristics are listed in Table 1. The patients received a homograft in the aortic position because of acute complex endocarditis. Thirty-one (43%) patients had undergone previous cardiac operations: aortic valve replacement (n ¼ 19), aortic valve replacement combined with coronary artery bypass grafting (CABG) (n ¼ 6), Bentall procedures (n ¼ 2), Bentall procedures combined with CABG (n ¼ 2), and atrial septal defect closure (n ¼ 2). Acute endocarditis was of bacterial (n ¼ 68) or fungal (n ¼ 1) origin. The following micro-organisms were found: Staphylococcus aureus, methicillin-resistant S 0003-4975/$36.00 http://dx.doi.org/10.1016/j.athoracsur.2014.11.002
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Surgical Procedures
Table 1. Patient Demographics Variable
Aortic Homograft 69 19 female 55 (25–50) 25 3 13 6 7 15 16 9 9 6 22 6 4 9 77 10 4 4 10 20 53 13 12
AMI ¼ acute myocardial infarction; CAD ¼ coronary artery disease; COPD ¼ chronic obstructive pulmonary disease; NYHA ¼ New York Heart Association; TIA ¼ transient ischemic attack.
aureus, Streptococcus viridans, S milleri, S bovis, S epidermidis, S sanguis, and S mutans, Enterococcus faecalis, Pseudomonas, and Candida. Aortic valve pathologic processes were restricted to the leaflets (vegetations or perforations, or both) in 17 patients (24%). The other patients had either additional abscess formation in the aortic annulus (n ¼ 13 [19%]) additional abscess formation in the annulus extending to the left ventricular outflow tract (LVOT) musculature causing aortoventricular discontinuity (n ¼ 26 [38%]) or periannular abscess formation which induced intracardiac fistulas extending to the left or right ventricle (n ¼ 11 [16%]). In 1 case, only the aortic wall was infected, with minor involvement of the aortic valve. In 6 patients with primary infection of the aortic root, the endocarditis process extended to the anterior leaflet of the native mitral valve. In these cases, there was always destruction of the anterior part of the mitral annulus combined with abscess formation within the anterior mitral leaflet. In none of these patients did the chords showed visible involvement. In 1 patient, the posterior leaflet also showed a vegetation.
All operations were performed between 1991 and 2003. In aortic valve endocarditis, the subcoronary implantation technique was used in 8 patients showing only leaflet involvement (11%). In all other patients, full aortic root replacement was performed. In 31 patients (45%), the proximal anastomosis was made at the annular level, and in 4 patients (6%) it was made at the level of the LVOT because of massive destruction at the annular level. In 19 patients (27%), subannular defects were closed using the anterior mitral leaflet of the aortic homograft. The average size of the aortic homograft was 20 mm (range, 19–29 mm). Concomitant operations were performed in 24 patients (35%): mitral valve replacement (n ¼ 3), mitral valve repair (n ¼ 3), tricuspid valve repair (n ¼ 1), CABG (n ¼ 9), LVOT reconstruction with a patch (n ¼ 6), and closure of a VSD with a patch (n ¼ 2). In 6 patients, the anterior leaflet of the mitral valve was also involved in the infectious process and was secondary to the aortic valve endocarditis. Because the chords were never involved, the anterior leaflet of the implanted aortic homograft root could be used to replace the infected native leaflet, with preservation of the native chords in 5 of 6 cases. If necessary, polytetrafluoroethylene chords were also implanted. In 3 patients, a mitral annuloplasty ring was added. In 1 patient, a separate mitral homograft was used to replace the anterior leaflet of the mitral valve. In this patient, the mitral leaflet of the aortic homograft root had already been used to close a subannular muscle defect.
Follow-Up Mean follow-up duration was 8.1 5.1 years (409 patientyears; maximum follow-up, 22 years). Clinical follow-up was 100% complete. Serial echocardiography was performed on a yearly basis by the referring cardiologist. For the formulation of valve-related complications, standard guidelines and definitions of terms were used according to published recommendations [8]. SVD was diagnosed as being either stenosis-type SVD or regurgitation-type SVD [6].
Statistical Analysis Kaplan-Meier curves were constructed for survival, freedom from reoperation, and freedom from SVD. For these analyses, only the hospital survivors were taken into account. STATISTICA, version 12.0 (StatSoft, Tulsa, OK) was used for analysis.
Results Hospital Mortality Hospital mortality was 24% (17 of 69 cases). Causes of death included septic shock (n ¼ 8, including 1 patient who received a combined aortic and partial mitral homograft), bleeding complications or tamponade, or both (n ¼ 8), and ventricular fibrillation (n ¼ 1). Time of death varied between 1 day and 5 months postoperatively. In
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Number of patients Sex Age (y), mean (range) Smoking (% of patients) Family history CAD (%) Diabetes (%) Obesity (%) Hypercholesterolemia (%) Renal failure (%) Hypertension (%) Pulmonary hypertension (%) Stroke (%) TIA (%) Cardiomegaly (%) COPD (%) Previous AMI (%) Cardiogenic shock (%) Sinus rhythm (%) Atrial fibrillation (%) Pacemaker (%) NYHA functional class (%) I II III IV V Septic embolization (%)
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76% of hospital deaths, the patients had an annular abscess perforating to the left or right ventricle with or without involvement of the mitral or tricuspid valve. However, of the 6 patients receiving a combined aortic and partial mitral valve homograft, 5 were hospital survivors.
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After partial mitral homograft implantation, no SVD was found up to 8 years postoperatively; however, a flail native posterior leaflet developed in 1 of these patients and successful reoperation was performed.
Comment Reoperation Rate and Long-Term Survival After aortic homograft implantation, long-term survival was 73% at 10 years, and 16 of 69 patients had to undergo reoperation (3 for endocarditis and 13 for SVD). Freedom of reoperation was 74% at 10 years (Fig 1). In patients in whom aortic homograft implantation was combined with partial mitral homograft implantation, 4 of 5 hospital survivors were doing well at 3 to 8 years after operation. The fifth patient underwent successful reoperation at 2 months for reconstruction of a flail native posterior leaflet.
Recurrence of Endocarditis Recurrence of endocarditis was 7% (5 of 69 cases). All except 1 case were early, ie, within 1 year postoperatively. Three of these patients underwent successful reoperation.
At present, it is not clear whether homografts are superior to other types of replacement valves in cases of endocarditis. A recent review states that the choice of valve type is mainly based on patient age, life expectancy, feasibility of anticoagulation, and the extent of the valve pathologic process [9]. In the setting of aortic root abscess, we found a recurrence of endocarditis of 7% using homografts. This is in accordance with data from the literature [2, 3, 10–12]. Our mean follow-up was 8 5 years and, remarkably, all cases of recurrent infection except 1 were within the first postoperative year. Leontyev and colleagues [13] described the outcome of operations for active infective endocarditis with aortic root abscess formation using mechanical or bioprosthetic valves. Surgical intervention consisted of radical resection of the abscess,
Structural Valve Degeneration After aortic homograft implantation, 20 of 69 patients experienced SVD (29%). Freedom from SVD at 10 years was 60.0% (Fig 1). Regarding the hospital survivors only, 20 of 52 patients (38%) experienced SVD, as diagnosed by echocardiography. Twenty-three percent (12 of 52 patients) had a stenosis-type SVD and 15% (8 of 52 patients) had a regurgitation-type SVD. Reoperation for SVD was performed in 23% (12 of 52) of patients. All patients except 1 survived reoperation and had a further uneventful follow-up. In the case of stenosis-type SVD, reoperation was complex because of the extensive calcification of the aortic root as well as the leaflets (Fig 2).
Fig 1. Freedom from structural valve degeneration (SVD) and reoperation. Kaplan-Meier curves showing freedom from SVD (blue line) and reoperation (red line) in homografts used to treat complex aortic valve endocarditis. Note that not all patients experiencing SVD underwent reoperation.
Fig 2. Roentgenogram from an explanted aortic homograft root explanted 10 years after implantation in a case of extensive aortic valve endocarditis. Note the important wall calcification of the entire root.
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bioprosthetic roots in elderly patients with extensive aortic root endocarditis. However, this brings about some technical drawbacks because many cases of complex endocarditis are associated with abscesses spreading into the perivalvular structures. These fistulas in the LVOT can be easily closed, after careful removal of debris, by the anterior mitral valve leaflet of the aortic homograft. In the case of pulmonary homografts or stentless bioprostheses, other techniques including autologous or bovine pericardial tissue must be used to repair these defects [21]. In conclusion, this study suggests that the use of homografts to reconstruct complex valve endocarditis is associated with low recurrence rates of infection but a high incidence of SVD in the long run.
References 1. Perrotta S, Lentini S. In patients with severe active aortic valve endocarditis, is a stentless valve as good as the homograft? Interact Cardiovasc Thorac Surg 2010;11:309–13. 2. Musci M, Weng Y, Hubler M, et al. Homograft aortic root replacement in native or prosthetic active infective endocarditis: twenty-year single-center experience. J Thorac Cardiovasc Surg 2010;139:665–73. 3. O’Brien MF, Harrocks S, Stafford EG, et al. The homograft aortic valve: a 29-year, 99.3% follow up of 1,022 valve replacements. J Heart Valve Dis 2001;10:334–44. 4. Yacoub M, Rasmi NR, Sundt TM, et al. Fourteen-year experience with homovital homografts for aortic valve replacement. J Thorac Cardiovasc Surg 1995;110:186–93. 5. El-Hamamsy I, Clark L, Stevens LM, et al. Late outcomes following freestyle versus homograft aortic root replacement: Results from a prospective randomized trial. J Am Coll Cardiol 2010;55:368–76. 6. Flameng W, Herregods MC, Vercalsteren M, Herijgers P, Bogaerts K, Meuris B. Prosthesis-patient mismatch predicts structural valve degeneration in bioprosthetic heart valves. Circulation 2010;121:2123–9. 7. Jashari R, Van HB, Ngakam R, Goffin Y, Fan Y. Banking of cryopreserved arterial allografts in Europe: 20 years of operation in the European Homograft Bank EHB. in Brussels. Cell Tissue Bank 2013;14:589–99. 8. Akins CW, Miller DC, Turina MI, et al. Guidelines for reporting mortality and morbidity after cardiac valve interventions. Ann Thorac Surg 2008;85:1490–5. 9. Manne MB, Shrestha NK, Lytle BW, et al. Outcomes after surgical treatment of native and prosthetic valve infective endocarditis. Ann Thorac Surg 2012;93:489–93. 10. Vogt PR, Von Segesser LK, Jenni R, et al. Emergency surgery for acute infective aortic valve endocarditis: performance of cryopreserved homografts and mode of failure. Eur J Cardiothorac Surg 1997;11:53–61. 11. Yankah AC, Pasic M, Klose H, Siniawski H, Weng Y, Hetzer R. Homograft reconstruction of the aortic root for endocarditis with periannular abscess: a 17-year study. Eur J Cardiothorac Surg 2005;28:69–75. 12. Jassar AS, Bavaria JE, Szeto WY, et al. Graft selection for aortic root replacement in complex active endocarditis: does it matter? Ann Thorac Surg 2012;93:480–7. 13. Leontyev S, Borger MA, Modi P, et al. Surgical management of aortic root abscess: a 13-year experience in 172 patients with 100% follow-up. J Thorac Cardiovasc Surg 2012;143: 332–7. 14. Fedoruk LM, Jamieson WR, Ling H, et al. Predictors of recurrence and reoperation for prosthetic valve endocarditis after valve replacement surgery for native valve endocarditis. J Thorac Cardiovasc Surg 2009;137:326–33.
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reconstruction of the annulus with patches, and artificial valve replacement. Recurrence of endocarditis was found in 8.7% of cases at a mean of 1.8 years after operation. Mean follow-up was 4 years. In another study on the outcome of surgical reconstruction of complex annular endocarditis using mechanical and bioprosthetic valves, there was a recurrence of endocarditis of 22% at 15-year follow-up [14]. Prosthesis type was not predictive for reoperation rate. In a review of 41 articles, Newton and Hunter [15] addressed the question “What type of valve replacement should be used in patients with endocarditis? They found that in mechanical valve replacement, the average endocarditis recurrence rate ranged from 3% to 9%, and in biological valves it was 7% to 29%. Fifty percent of the studies recommended a mechanical valve for low recurrence rates and high survival rates, but the other 50% found no difference. However, recurrence of endocarditis is not the only determinant of long-term outcome. Besides complications of long-term anticoagulation therapy, associated with the use of mechanical valves, SVD is an important issue with the use of biological valves, including homografts. Although it is known that the incidence of SVD in bioprosthetic valves is variable and determined by many factors, it is not systematically studied in the setting of complex postendocarditis aortic valve replacement [6]. Moon and coworkers [16] reported that freedom from reoperation for patients with a biological valve who were younger than 60 years of age was low (only 19% at 15 years) but that for patients older then 65 years it was much better (84% at 15 years). Further data are scarce and relate to data of mixed populations of patients and valve types [17]. We found that SVD of the aortic homografts used in complex endocarditis is high—it reaches 40% at 10 years of follow-up. The incidence of the stenosis type of SVD is about twice as high as the incidence of the regurgitation type of SVD. This can be explained by the fact that in the majority of cases, an aortic, not a pulmonary, homograft was used for replacement. We know from our previous experimental work, as well as from some clinical data, that the pulmonary homograft is less sensitive to calcification than is the aortic homograft [18, 19]. In the case of a regurgitation type of SVD, the valve insufficiency was related to either annular dilatation or cusp rupture. However, in the case of a stenosis type of SVD, the aortic homograft is completely calcified, including the aortic root itself, and this makes reoperation more complex. As can be seen in Fig 2, the calcified aortic core, the sinuses, and the valve leaflets can be dissected free as a whole and replaced by a composite valve or stentless bioprosthesis. This was described by David [20]. It was remarkable that we never found SVD in the transplanted anterior leaflet after partial mitral homograft implantation. This study suggests that although the recurrence rate of endocarditis is low after implantation of an aortic root homograft, more than one third of hospital survivors experience SVD during follow-up. It should therefore be considered preferable to use either pulmonary homografts in younger patients or stentless porcine
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15. Newton S, Hunter S. What type of valve replacement should be used in patients with endocarditis? Interact Cardiovasc Thorac Surg 2010;11:784–8. 16. Moon MR, Miller DC, Moore KA, et al. Treatment of endocarditis with valve replacement: the question of tissue versus mechanical prosthesis. Ann Thorac Surg 2001;71:1164–71. 17. David TE, Gavra G, Feindel CM, Regesta T, Armstrong S, Maganti MD. Surgical treatment of active infective endocarditis: a continued challenge. J Thorac Cardiovasc Surg 2007;133:144–9. 18. Flameng W, Jashari R, De VG, Mesure L, Meuris B. Calcification of allograft and stentless xenograft valves for right
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ventricular outflow tract reconstruction: an experimental study in adolescent sheep. J Thorac Cardiovasc Surg 2011;141:1513–21. 19. Tweddell JS, Pelech AN, Frommelt PC, et al. Factors affecting longevity of homograft valves used in right ventricular outflow tract reconstruction for congenital heart disease. Circulation 2000;102(19 suppl 3):III130–5. 20. David TE. Surgical management of aortic root abscess. J Card Surg 1997;12(2 suppl):262–6. 21. d’Udekem Y, David TE, Feindel CM, Armstrong S, Sun Z. Long-term results of surgery for active infective endocarditis. Eur J Cardiothorac Surg 1997;11:46–52.
Notice From the American Board of Thoracic Surgery The 2015 Part I (written) examination will be held on Monday, November 16, 2015, at multiple sites throughout the United States using an electronic format. The closing date for registration is August 15, 2015. Those wishing to be considered for examination must apply online at www.abts.org. To be admissible to the Part II (oral) examination, a candidate must have successfully completed the Part I (written)
Ó 2015 by The Society of Thoracic Surgeons Published by Elsevier
examination. A candidate applying for admission to the certifying examination must fulfill all the requirements of the Board in force at the time the application is received. Please address all communications to the American Board of Thoracic Surgery, 633 N St. Clair St, Suite 2320, Chicago, IL 60611; telephone: (312) 202-5900; fax: (312) 202-5960; e-mail: [email protected].
Ann Thorac Surg 2015;99:1238
0003-4975/$36.00
Durability of Homografts Used to Treat Complex Aortic Valve Endocarditis Willem Flameng, MD, PhD, Willem Daenen, MD, Ramadan Jashari, MD, Paul Herijgers, MD, PhD, and Bart Meuris, MD, PhD Department of Cardiac Surgery, KU Leuven, University Hospitals Leuven, Leuven, and European Homograft Bank, Brussels, Belgium
Background. Acute bacterial endocarditis may be extremely destructive for cardiac valves and their periannular structures. It has been suggested that complex reconstruction procedures require the use of homografts because of their versatility and potency to resist repeated infection. Methods. We studied the long-term results of 69 patients with complex endocarditis who received homografts in the aortic position. Results. The results after a mean follow-up of 8.1 ± 5.1 years (median, 8.0 years) showed that the recurrence of
endocarditis even in these complex cases is low (7%), but the incidence of structural valve degeneration (SVD) is high. Freedom from SVD at 10 years is only 60.0%. When aortic homografts degenerate, they predominantly calcify. Conclusions. The use of homografts to reconstruct endocarditis-related aortic valve destruction is associated with a low recurrence of endocarditis but a high incidence of SVD in the long run.
I
Material and Methods
n the literature, the use of a homograft as treatment for acute aortic endocarditis has been associated with a lower incidence of recurrence of endocarditis than has the use of a prosthetic valve [1]. Therefore the homograft has been advocated as the first choice to replace an infected valve [2]. In contrast, from long-term studies in nonendocarditis valve pathologic conditions, we have learned that homografts are prone to structural valve degeneration (SVD), mainly in younger patients [3, 4]. Even in elderly patients, significantly more valve degeneration and a higher need for reoperation has been reported after aortic root replacement with a homograft than after the use of a Freestyle bioprosthesis (Medtronic Inc, Minneapolis, MN) [5]. Specifically in the setting of acute bacterial endocarditis, long-term durability of homografts has never been systematically studied. Also, whenever the durability of homografts implanted for endocarditis has occasionally been reported, it was regarding the need for reoperation and not based on echocardiographic criteria of valve function. It can be shown in previous reports that the reoperation rate significantly underestimates the rate of SVD [6]. In the present study, we describe the long-term results of 69 patients undergoing aortic valve replacement for acute complex bacterial endocarditis. Besides mortality, reoperation rates, and recurrence of endocarditis, the development of SVD based on serial echocardiography is reported.
Accepted for publication Nov 3, 2014. Address correspondence to Dr Meuris, Department of Cardiac Surgery, UZ Gasthuisberg, Herestraat 49, B-3000 Leuven, Belgium; e-mail: bart. [email protected].
Ó 2015 by The Society of Thoracic Surgeons Published by Elsevier
(Ann Thorac Surg 2015;99:1234–8) Ó 2015 by The Society of Thoracic Surgeons
The study was approved by the Ethical Committee of the University Hospitals Leuven (Belgium), and the need for individual patient consent was waived.
Homografts Cryopreserved homografts were provided by the European Homograft Bank and processed as described previously [7]. Sixty-six aortic and 3 pulmonary homografts were used. In most cases, aortic root homografts had the anterior mitral valve leaflet preserved during graft procurement. This allowed the closure of subannular defects in extensive aortic root destruction as well as simultaneous replacement of the entire recipient anterior mitral leaflet together with aortic root replacement (surgical details are described further on).
Patient Population and Valve Pathologic Processes A total of 69 patients were operated on for congestive heart failure caused by severe valve insufficiency eventually combined with septic systemic embolization. All characteristics are listed in Table 1. The patients received a homograft in the aortic position because of acute complex endocarditis. Thirty-one (43%) patients had undergone previous cardiac operations: aortic valve replacement (n ¼ 19), aortic valve replacement combined with coronary artery bypass grafting (CABG) (n ¼ 6), Bentall procedures (n ¼ 2), Bentall procedures combined with CABG (n ¼ 2), and atrial septal defect closure (n ¼ 2). Acute endocarditis was of bacterial (n ¼ 68) or fungal (n ¼ 1) origin. The following micro-organisms were found: Staphylococcus aureus, methicillin-resistant S 0003-4975/$36.00 http://dx.doi.org/10.1016/j.athoracsur.2014.11.002
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Surgical Procedures
Table 1. Patient Demographics Variable
Aortic Homograft 69 19 female 55 (25–50) 25 3 13 6 7 15 16 9 9 6 22 6 4 9 77 10 4 4 10 20 53 13 12
AMI ¼ acute myocardial infarction; CAD ¼ coronary artery disease; COPD ¼ chronic obstructive pulmonary disease; NYHA ¼ New York Heart Association; TIA ¼ transient ischemic attack.
aureus, Streptococcus viridans, S milleri, S bovis, S epidermidis, S sanguis, and S mutans, Enterococcus faecalis, Pseudomonas, and Candida. Aortic valve pathologic processes were restricted to the leaflets (vegetations or perforations, or both) in 17 patients (24%). The other patients had either additional abscess formation in the aortic annulus (n ¼ 13 [19%]) additional abscess formation in the annulus extending to the left ventricular outflow tract (LVOT) musculature causing aortoventricular discontinuity (n ¼ 26 [38%]) or periannular abscess formation which induced intracardiac fistulas extending to the left or right ventricle (n ¼ 11 [16%]). In 1 case, only the aortic wall was infected, with minor involvement of the aortic valve. In 6 patients with primary infection of the aortic root, the endocarditis process extended to the anterior leaflet of the native mitral valve. In these cases, there was always destruction of the anterior part of the mitral annulus combined with abscess formation within the anterior mitral leaflet. In none of these patients did the chords showed visible involvement. In 1 patient, the posterior leaflet also showed a vegetation.
All operations were performed between 1991 and 2003. In aortic valve endocarditis, the subcoronary implantation technique was used in 8 patients showing only leaflet involvement (11%). In all other patients, full aortic root replacement was performed. In 31 patients (45%), the proximal anastomosis was made at the annular level, and in 4 patients (6%) it was made at the level of the LVOT because of massive destruction at the annular level. In 19 patients (27%), subannular defects were closed using the anterior mitral leaflet of the aortic homograft. The average size of the aortic homograft was 20 mm (range, 19–29 mm). Concomitant operations were performed in 24 patients (35%): mitral valve replacement (n ¼ 3), mitral valve repair (n ¼ 3), tricuspid valve repair (n ¼ 1), CABG (n ¼ 9), LVOT reconstruction with a patch (n ¼ 6), and closure of a VSD with a patch (n ¼ 2). In 6 patients, the anterior leaflet of the mitral valve was also involved in the infectious process and was secondary to the aortic valve endocarditis. Because the chords were never involved, the anterior leaflet of the implanted aortic homograft root could be used to replace the infected native leaflet, with preservation of the native chords in 5 of 6 cases. If necessary, polytetrafluoroethylene chords were also implanted. In 3 patients, a mitral annuloplasty ring was added. In 1 patient, a separate mitral homograft was used to replace the anterior leaflet of the mitral valve. In this patient, the mitral leaflet of the aortic homograft root had already been used to close a subannular muscle defect.
Follow-Up Mean follow-up duration was 8.1 5.1 years (409 patientyears; maximum follow-up, 22 years). Clinical follow-up was 100% complete. Serial echocardiography was performed on a yearly basis by the referring cardiologist. For the formulation of valve-related complications, standard guidelines and definitions of terms were used according to published recommendations [8]. SVD was diagnosed as being either stenosis-type SVD or regurgitation-type SVD [6].
Statistical Analysis Kaplan-Meier curves were constructed for survival, freedom from reoperation, and freedom from SVD. For these analyses, only the hospital survivors were taken into account. STATISTICA, version 12.0 (StatSoft, Tulsa, OK) was used for analysis.
Results Hospital Mortality Hospital mortality was 24% (17 of 69 cases). Causes of death included septic shock (n ¼ 8, including 1 patient who received a combined aortic and partial mitral homograft), bleeding complications or tamponade, or both (n ¼ 8), and ventricular fibrillation (n ¼ 1). Time of death varied between 1 day and 5 months postoperatively. In
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Number of patients Sex Age (y), mean (range) Smoking (% of patients) Family history CAD (%) Diabetes (%) Obesity (%) Hypercholesterolemia (%) Renal failure (%) Hypertension (%) Pulmonary hypertension (%) Stroke (%) TIA (%) Cardiomegaly (%) COPD (%) Previous AMI (%) Cardiogenic shock (%) Sinus rhythm (%) Atrial fibrillation (%) Pacemaker (%) NYHA functional class (%) I II III IV V Septic embolization (%)
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76% of hospital deaths, the patients had an annular abscess perforating to the left or right ventricle with or without involvement of the mitral or tricuspid valve. However, of the 6 patients receiving a combined aortic and partial mitral valve homograft, 5 were hospital survivors.
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After partial mitral homograft implantation, no SVD was found up to 8 years postoperatively; however, a flail native posterior leaflet developed in 1 of these patients and successful reoperation was performed.
Comment Reoperation Rate and Long-Term Survival After aortic homograft implantation, long-term survival was 73% at 10 years, and 16 of 69 patients had to undergo reoperation (3 for endocarditis and 13 for SVD). Freedom of reoperation was 74% at 10 years (Fig 1). In patients in whom aortic homograft implantation was combined with partial mitral homograft implantation, 4 of 5 hospital survivors were doing well at 3 to 8 years after operation. The fifth patient underwent successful reoperation at 2 months for reconstruction of a flail native posterior leaflet.
Recurrence of Endocarditis Recurrence of endocarditis was 7% (5 of 69 cases). All except 1 case were early, ie, within 1 year postoperatively. Three of these patients underwent successful reoperation.
At present, it is not clear whether homografts are superior to other types of replacement valves in cases of endocarditis. A recent review states that the choice of valve type is mainly based on patient age, life expectancy, feasibility of anticoagulation, and the extent of the valve pathologic process [9]. In the setting of aortic root abscess, we found a recurrence of endocarditis of 7% using homografts. This is in accordance with data from the literature [2, 3, 10–12]. Our mean follow-up was 8 5 years and, remarkably, all cases of recurrent infection except 1 were within the first postoperative year. Leontyev and colleagues [13] described the outcome of operations for active infective endocarditis with aortic root abscess formation using mechanical or bioprosthetic valves. Surgical intervention consisted of radical resection of the abscess,
Structural Valve Degeneration After aortic homograft implantation, 20 of 69 patients experienced SVD (29%). Freedom from SVD at 10 years was 60.0% (Fig 1). Regarding the hospital survivors only, 20 of 52 patients (38%) experienced SVD, as diagnosed by echocardiography. Twenty-three percent (12 of 52 patients) had a stenosis-type SVD and 15% (8 of 52 patients) had a regurgitation-type SVD. Reoperation for SVD was performed in 23% (12 of 52) of patients. All patients except 1 survived reoperation and had a further uneventful follow-up. In the case of stenosis-type SVD, reoperation was complex because of the extensive calcification of the aortic root as well as the leaflets (Fig 2).
Fig 1. Freedom from structural valve degeneration (SVD) and reoperation. Kaplan-Meier curves showing freedom from SVD (blue line) and reoperation (red line) in homografts used to treat complex aortic valve endocarditis. Note that not all patients experiencing SVD underwent reoperation.
Fig 2. Roentgenogram from an explanted aortic homograft root explanted 10 years after implantation in a case of extensive aortic valve endocarditis. Note the important wall calcification of the entire root.
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bioprosthetic roots in elderly patients with extensive aortic root endocarditis. However, this brings about some technical drawbacks because many cases of complex endocarditis are associated with abscesses spreading into the perivalvular structures. These fistulas in the LVOT can be easily closed, after careful removal of debris, by the anterior mitral valve leaflet of the aortic homograft. In the case of pulmonary homografts or stentless bioprostheses, other techniques including autologous or bovine pericardial tissue must be used to repair these defects [21]. In conclusion, this study suggests that the use of homografts to reconstruct complex valve endocarditis is associated with low recurrence rates of infection but a high incidence of SVD in the long run.
References 1. Perrotta S, Lentini S. In patients with severe active aortic valve endocarditis, is a stentless valve as good as the homograft? Interact Cardiovasc Thorac Surg 2010;11:309–13. 2. Musci M, Weng Y, Hubler M, et al. Homograft aortic root replacement in native or prosthetic active infective endocarditis: twenty-year single-center experience. J Thorac Cardiovasc Surg 2010;139:665–73. 3. O’Brien MF, Harrocks S, Stafford EG, et al. The homograft aortic valve: a 29-year, 99.3% follow up of 1,022 valve replacements. J Heart Valve Dis 2001;10:334–44. 4. Yacoub M, Rasmi NR, Sundt TM, et al. Fourteen-year experience with homovital homografts for aortic valve replacement. J Thorac Cardiovasc Surg 1995;110:186–93. 5. El-Hamamsy I, Clark L, Stevens LM, et al. Late outcomes following freestyle versus homograft aortic root replacement: Results from a prospective randomized trial. J Am Coll Cardiol 2010;55:368–76. 6. Flameng W, Herregods MC, Vercalsteren M, Herijgers P, Bogaerts K, Meuris B. Prosthesis-patient mismatch predicts structural valve degeneration in bioprosthetic heart valves. Circulation 2010;121:2123–9. 7. Jashari R, Van HB, Ngakam R, Goffin Y, Fan Y. Banking of cryopreserved arterial allografts in Europe: 20 years of operation in the European Homograft Bank EHB. in Brussels. Cell Tissue Bank 2013;14:589–99. 8. Akins CW, Miller DC, Turina MI, et al. Guidelines for reporting mortality and morbidity after cardiac valve interventions. Ann Thorac Surg 2008;85:1490–5. 9. Manne MB, Shrestha NK, Lytle BW, et al. Outcomes after surgical treatment of native and prosthetic valve infective endocarditis. Ann Thorac Surg 2012;93:489–93. 10. Vogt PR, Von Segesser LK, Jenni R, et al. Emergency surgery for acute infective aortic valve endocarditis: performance of cryopreserved homografts and mode of failure. Eur J Cardiothorac Surg 1997;11:53–61. 11. Yankah AC, Pasic M, Klose H, Siniawski H, Weng Y, Hetzer R. Homograft reconstruction of the aortic root for endocarditis with periannular abscess: a 17-year study. Eur J Cardiothorac Surg 2005;28:69–75. 12. Jassar AS, Bavaria JE, Szeto WY, et al. Graft selection for aortic root replacement in complex active endocarditis: does it matter? Ann Thorac Surg 2012;93:480–7. 13. Leontyev S, Borger MA, Modi P, et al. Surgical management of aortic root abscess: a 13-year experience in 172 patients with 100% follow-up. J Thorac Cardiovasc Surg 2012;143: 332–7. 14. Fedoruk LM, Jamieson WR, Ling H, et al. Predictors of recurrence and reoperation for prosthetic valve endocarditis after valve replacement surgery for native valve endocarditis. J Thorac Cardiovasc Surg 2009;137:326–33.
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reconstruction of the annulus with patches, and artificial valve replacement. Recurrence of endocarditis was found in 8.7% of cases at a mean of 1.8 years after operation. Mean follow-up was 4 years. In another study on the outcome of surgical reconstruction of complex annular endocarditis using mechanical and bioprosthetic valves, there was a recurrence of endocarditis of 22% at 15-year follow-up [14]. Prosthesis type was not predictive for reoperation rate. In a review of 41 articles, Newton and Hunter [15] addressed the question “What type of valve replacement should be used in patients with endocarditis? They found that in mechanical valve replacement, the average endocarditis recurrence rate ranged from 3% to 9%, and in biological valves it was 7% to 29%. Fifty percent of the studies recommended a mechanical valve for low recurrence rates and high survival rates, but the other 50% found no difference. However, recurrence of endocarditis is not the only determinant of long-term outcome. Besides complications of long-term anticoagulation therapy, associated with the use of mechanical valves, SVD is an important issue with the use of biological valves, including homografts. Although it is known that the incidence of SVD in bioprosthetic valves is variable and determined by many factors, it is not systematically studied in the setting of complex postendocarditis aortic valve replacement [6]. Moon and coworkers [16] reported that freedom from reoperation for patients with a biological valve who were younger than 60 years of age was low (only 19% at 15 years) but that for patients older then 65 years it was much better (84% at 15 years). Further data are scarce and relate to data of mixed populations of patients and valve types [17]. We found that SVD of the aortic homografts used in complex endocarditis is high—it reaches 40% at 10 years of follow-up. The incidence of the stenosis type of SVD is about twice as high as the incidence of the regurgitation type of SVD. This can be explained by the fact that in the majority of cases, an aortic, not a pulmonary, homograft was used for replacement. We know from our previous experimental work, as well as from some clinical data, that the pulmonary homograft is less sensitive to calcification than is the aortic homograft [18, 19]. In the case of a regurgitation type of SVD, the valve insufficiency was related to either annular dilatation or cusp rupture. However, in the case of a stenosis type of SVD, the aortic homograft is completely calcified, including the aortic root itself, and this makes reoperation more complex. As can be seen in Fig 2, the calcified aortic core, the sinuses, and the valve leaflets can be dissected free as a whole and replaced by a composite valve or stentless bioprosthesis. This was described by David [20]. It was remarkable that we never found SVD in the transplanted anterior leaflet after partial mitral homograft implantation. This study suggests that although the recurrence rate of endocarditis is low after implantation of an aortic root homograft, more than one third of hospital survivors experience SVD during follow-up. It should therefore be considered preferable to use either pulmonary homografts in younger patients or stentless porcine
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15. Newton S, Hunter S. What type of valve replacement should be used in patients with endocarditis? Interact Cardiovasc Thorac Surg 2010;11:784–8. 16. Moon MR, Miller DC, Moore KA, et al. Treatment of endocarditis with valve replacement: the question of tissue versus mechanical prosthesis. Ann Thorac Surg 2001;71:1164–71. 17. David TE, Gavra G, Feindel CM, Regesta T, Armstrong S, Maganti MD. Surgical treatment of active infective endocarditis: a continued challenge. J Thorac Cardiovasc Surg 2007;133:144–9. 18. Flameng W, Jashari R, De VG, Mesure L, Meuris B. Calcification of allograft and stentless xenograft valves for right
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ventricular outflow tract reconstruction: an experimental study in adolescent sheep. J Thorac Cardiovasc Surg 2011;141:1513–21. 19. Tweddell JS, Pelech AN, Frommelt PC, et al. Factors affecting longevity of homograft valves used in right ventricular outflow tract reconstruction for congenital heart disease. Circulation 2000;102(19 suppl 3):III130–5. 20. David TE. Surgical management of aortic root abscess. J Card Surg 1997;12(2 suppl):262–6. 21. d’Udekem Y, David TE, Feindel CM, Armstrong S, Sun Z. Long-term results of surgery for active infective endocarditis. Eur J Cardiothorac Surg 1997;11:46–52.
Notice From the American Board of Thoracic Surgery The 2015 Part I (written) examination will be held on Monday, November 16, 2015, at multiple sites throughout the United States using an electronic format. The closing date for registration is August 15, 2015. Those wishing to be considered for examination must apply online at www.abts.org. To be admissible to the Part II (oral) examination, a candidate must have successfully completed the Part I (written)
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examination. A candidate applying for admission to the certifying examination must fulfill all the requirements of the Board in force at the time the application is received. Please address all communications to the American Board of Thoracic Surgery, 633 N St. Clair St, Suite 2320, Chicago, IL 60611; telephone: (312) 202-5900; fax: (312) 202-5960; e-mail: [email protected].
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