St. Jude Medical and CarboMedics Mechanical Heart Valves in the Aortic Position

Clinical Investigation Ozer Kandemir, MD Hilmi Tokmakoglu, MD Ulku Yildiz, MD Tevfik Tezcaner, MD A. Cem Yorgancioglu, MD Ilhan Gunay, MD Kaya Suzer, MD Yaman Zorlutuna, MD St. Jude Medical and CarboMedics Mechanical Heart Valves in the Aortic Position Comparison of Long-Term Results We designed this study to compare long-term results of St. Jude Medical and CarboMedics mechanical heart valves in the aortic position. We retrospectively analyzed the results of 174 consecutive patients who received either a St. Jude (n=80) or a CarboMedics (n=94) mechanical aortic valve from March 1992 through October 2004. The follow-up rate was 97.7%. The mean follow-up duration for the St. Jude group was 79.3 ± 35.0 and for the CarboMedics group, 70.0 ± 34.3 months. The cumulative follow-up was 523.8 and 530.1 patient-years, respectively. The 30-day mortality rates for the St. Jude and CarboMedics patients were 1.3% and 3.2%, respectively. The actuarial survival rate for the St. Jude group at 138.0 ± 4.7 months was 75.9% ± 0.1% and for the CarboMedics group at 130.8 ± 4.8 months was 69.8% ± 0.1% (P=NS). There was no structural valve deterioration in either group. Freedom from thromboembolic events was 87.7% for the St. Jude group and 83.0% for the CarboMedics group (P= NS). Freedom from bleeding events for the St. Jude group was 93.6% and for the CarboMedics group, 89.7% ( P=NS). The results obtained from this study indicate that standard St. Jude Medical and CarboMedics aortic valve prostheses offer similar excellent clinical performance. Definitive judgment must await trials that are extensive, randomized, and prospective. (Tex Heart Inst J 2006;33:154-9) Key words: Aortic valve; coronary thrombosis; heart valve prosthesis/adverse effects; postoperative complications; prosthesis design; thromboembolism/ prevention & control; treatment outcome From: Department of Cardiovascular Surgery, Bayindir Hospital, Ankara, Turkey Address for reprints: Ozer Kandemir, MD, Karaelmas Universitesi Tip Fakultesi, Kalp ve Damar Cerrahisi Anabilim Dali, Zonguldak, Turkey E-mail: ozerkandemir@isnet.net.tr 2006 by the Texas Heart Institute, Houston The ideal prosthetic heart valve should possess qualities that include good hemodynamic performance and durability, ease of insertion, and freedom from thromboembolic events. Although valve manufacturers aim for these objectives, no prosthetic valve has yet achieved a perfect performance profile in accordance with these criteria. Two of the most widely used mechanical heart valves are the standard St. Jude Medical Mechanical Heart Valve (SJM; St. Jude Medical Inc.; Minneapolis, Minn) and the CarboMedics Standard Aortic Valve (CM; CarboMedics, Inc.; Austin, Tex) bileaflet valve prostheses. There are several design features that distinguish the SJM from the CM valve. Both are constructed of pyrolytic carbon, but the CM valve has no pivot guards, struts, or orifice projections to impede blood flow and decrease turbulence through the valve. The sewing ring is coated with carbon to reduce the ingrowth of tissue that can lead to valve obstruction. The valve can rotate within the sewing ring. The leaflet opening angle is 78, as opposed to 85 in the SJM valve. In the open position, the CM valve leaflets protrude 2 mm farther beyond the orifice than do the SJM valve leaflets. 1, 2 Excellent results have been reported with use of the SJM and the CM valves, 3-6 and some reviewers have concluded that their rates for valve-related complications are highly similar. 7,8 We designed this retrospective study in order to compare the long-term results of these most widely used mechanical heart valves in the aortic position. Patients and Methods Patient Selection. From March 1992 through October 2004, 174 consecutive patients underwent implantation of a SJM or CM mechanical heart valve in the aor- 154 St. Jude and CarboMedics Valves in the Aortic Position Volume 33, Number 2, 2006

TABLE I. Patients Characteristics Variables St. Jude Medical CarboMedics P Value Patients (n) 80 94 Age (yr) 46.4 ± 16.6 48.7 ± 16.1 NS Male (%) 78.8 76.6 NS BSA (kg/m²) 1.77 ± 0.17 1.71 ± 0.18 NS NYHA class I 3 (3.7%) 2 (2.1%) NS II 46 (57.5%) 49 (52.1%) NS III 29 (36.3%) 39 (41.5%) NS IV 2 (2.5%) 4 4.3%) NS Atrial fibrillation 3 (3.8%) 4 (4.3%) NS BSA = body surface area; NYHA class = New York Heart Association functional class; NS = not significant tic position as a single procedure. Of these patients, 80 received SJM valves, and 94 received CM valves. The characteristics of the 2 groups of patients were similar and are summarized in Table I. Exclusion criteria included the receipt of other valve prostheses or of valves in positions other than the aortic, or the need for concomitant cardiac operation (such as coronary artery bypass grafting or ascending aorta surgery), reoperation, or aortic root enlargement. Surgical Procedures. Patients underwent operation via median sternotomy and aortocaval cannulation. Cardiopulmonary bypass was performed with a membrane oxygenator and a non-pulsatile roller pump. Mild hypothermia (rectal temperature, 28 32 C) was used, and 2.4-L/min/m 2 flow rates were maintained during bypass. Myocardial protection was supported with topical ice slush and intermittent antegrade blood cardioplegia, with or without retrograde cardioplegia as appropriate for the patient. If coronary sinus cannulation failed, cardioplegia was delivered into the coronary ostia. Valves were secured with pledgeted horizontal mattress sutures using 2-0 Ethibond (Ethicon, Inc., a Johnson & Johnson company; Somerville, NJ). Before the aortic cross-clamp was removed, patients received terminal warm cardioplegic solution. Anticoagulation Therapy. Warfarin therapy was started on postoperative day 1. The international normalized ratio (INR) was maintained within a range of 2.5 to 3.5, and the prothrombin time was 1.5 to 2.5 times baseline. After discharge from the hospital, the patients prothrombin times and INR levels were evaluated monthly. All patients received aspirin (300 mg/ day), except for those who had gastrointestinal intolerance. Follow-Up. All patients underwent follow-up evaluation 1, 3, and 6 months after routine discharge. After that, follow-up was performed annually with echocar- diographic assessment. A comprehensive follow-up survey included mail and telephone questionnaires. In addition performing the follow-up survey, we reviewed retrospectively the hospital records (subsequent to the prosthetic-valve implantation) and outpatient records of all patients who reported any major events. Statistical Analysis and Data Reporting. Hospital deaths, late deaths, and valve-related events were defined according to the published guidelines of the Society of Thoracic Surgeons. 9 Descriptive summaries are presented as frequencies and percentages for categorical data, and as means and standard deviations for continuous variables. Group comparisons were made using χ 2 tests. Kaplan-Meier survival analyses were performed to evaluate differences in freedom from thromboembolic events, bleeding events, and valverelated deaths between the 2 groups. All statistical analyses were performed using the SPSS statistical software package (release 13.0, SPSS Inc.; Chicago, Ill). Results Patient Characteristics. The mean age was 46.4 ± 16.6 years in the SJM group and 48.8 ± 16.1 years in the CM group (Table I). Most patients were in New York Heart Association (NYHA) functional class II (58.8% vs 52.7%) or class III (35.0% vs 41.9%), with no difference observed in overall NYHA class distribution between the SJM and CM groups. Preoperative echocardiographic data were also similar, and no statistical difference between the 2 groups was found (Table II). The origin and nature of the native valve abnormalities was similar, and the main cause was rheumatic disease (Table III). Four patients could not be contacted. The follow-up rate was 97.7%. The mean duration of follow-up was 79.3 ± 35.0 and 70.0 ± 34.3 months; the cumulative follow-up was 523.8 and 530.1 patient-years for the SJM and CM groups, respectively. Early Hemodynamic Data. Analysis revealed no statistical difference between the SJM and CM groups in perioperative and postoperative characteristics (Table IV). Low cardiac output was seen in 17 (23.6%) patients in the SJM group and 24 (25.5%) in the CM group (P=0.8). Postoperatively, a pacemaker was used in 3 (3.8%) patients in the SJM group and 3 (3.2%) patients in the CM group (P=0.5). Durations of postoperative intensive care and hospital stays were similar for the 2 groups. Early and Late Mortality. The early (30-day) mortality rate was 1.3% (1 patient) in the SJM group and 3.2% (3) in the CM group (P=0.6). The cause of death in the SJM group was low cardiac output. Causes of death in the CM group were multi-organ failure (1 patient), pneumonia (1 patient), and low cardiac Texas Heart Institute Journal St. Jude and CarboMedics Valves in the Aortic Position 155

TABLE II. Echocardiographic Data St. Jude Medical CarboMedics Data Preoperative Postoperative Preoperative Postoperative Ejection fraction 0.61 ± 0.08 0.64 ± 0.07 0.59 ± 0.10 0.64 ± 0.07* Gradient (mmhg) 66.8 ± 22.6 26.5 ± 10.8* 69.3 ± 22.8 23.6 ± 10.9* EDD (cm) 5.6 ± 0.8 4.8 ± 0.3* 5.1 ± 0.9 4.8 ± 0.4* ESD (cm) 3.6 ± 0.8 3.1 ± 0.2 3.5 ± 0.7 3.3 ± 0.5 Septum (cm) 1.3 ± 0.3 1.1 ± 0.2* 1.3 ± 0.2 1.2 ± 0.2 PWT (cm) 1.3 ± 0.2 1.2 ± 0.2 1.3 ± 0.2 1.2 ± 0.2 EDD = end-diastolic diameter; ESD = end-systolic diameter; PWT = posterior wall thickness *P <0.05 TABLE III. Cause of Valve Disease St. Jude Medical CarboMedics Cause No. (%) No. (%) Rheumatic 59 (73.8) 66 (70.2) Congenital 10 (12.5) 7 (7.4) Senile calcification 11 (13.8) 18 (19.1) Infective endocarditis 0 3 (3.8) output (1 patient). Eight late deaths occurred in the SJM group and 8 in the CM group. Actuarial survival for the SJM group at 138.0 ± 4.7 months was 75.9% ± 0.1% and for the CM group at 130.8 ± 4.8 months was 69.8% ± 0.1% (log rank, P=0.7) (Fig. 1). The causes of early and late death are summarized in Table V. Valve-Related Complications Thromboembolic Events. There were 6 thromboembolic events in the SJM group, 3 of which had neurologic consequences. One of them was reversible ischemic neurologic deficit, and the others were considered transient ischemic attacks. Thrombosis of a valve in the SJM group was attributed primarily to irregular use of warfarin, and it required reoperation. In the CM group, there were 5 thromboembolic events, 1 of which was a stroke with permanent effects; the others were transient ischemic attacks. The prominent rhythm of most patients with thromboembolic events was atrial fibrillation: 54% vs 61% in the SJM and CM groups, respectively. Freedom from any thromboembolic event was 87.7% in the SJM group, at a mean of 142.5 ± 3.7 months, and 83.0% in the CM group, at a mean of 136.2 ± 4.2 months (log rank, P=0.9) (Fig. 2). Bleeding Events. A total of 3 bleeding events was seen in the SJM group, compared with 4 in the CM group. These minor anticoagulant-related hemorrhages did not require hospitalization. Freedom from bleeding events in the SJM group at 147.3 ± 2.8 months was 93.6%, and in the CM group at 139.1 ± 2.3 months it was 89.7% (log rank, P=0.6) (Fig. 3). Other Complications. One late paravalvular leak occurred in the SJM group and resulted in reoperation for repair of the leak. There were no cases of paravalvular leak in the CM group. During the early follow-up period, 1 patient in the CM group underwent reoperation for class I aortic dissection, originating 2 cm above the prosthetic valve. There was no structural valve deterioration detected in either group during the follow-up period. NYHA Functional Class. Symptomatic improvement after aortic valve replacement is indicated clearly in Fig. 4, and no statistical differences were detected between the 2 groups (P=0.3) Discussion The main disadvantages of mechanical heart valves are their thromboembolic tendencies and the patients need to use anticoagulants for life, with the related risk of hemorrhage. To achieve perfect performance, a prosthetic valve should possess good hemodynamic performance and durability, ease of insertion, and freedom from thromboembolic events. Two of the most widely used mechanical heart valves are the St. Jude Medical and CarboMedics valves. Recent comparative nonrandomized studies have shown no significant differences between these prostheses. 10,11 However, some have reported that CM valves perform less efficiently in regard to thromboembolic complications than do SJM prostheses. 8,12 Few randomized studies 8 have compared early and midterm outcomes for the SJM and CM heart valves in the aortic position alone. The intraoperative and early postoperative performance of the 2 valves was similar. The hospital mortality reported here was lower in the SJM group, but 156 St. Jude and CarboMedics Valves in the Aortic Position Volume 33, Number 2, 2006

this difference did not reach statistical significance (1.3% vs 3.2%; P=0.6). Hospital mortality rates for the SJM valve have been reported to be between 2.4% 13 and 7%. 14 For patients receiving the CM valve, the rates have been reported between 0 15 and 5.3%. 16 Thromboembolism and anticoagulant-related bleeding remain the major impediments to successful use of mechanical valve prostheses; therefore, they are the most specific measures of valve performance. Anticoagulation management is the major determinant of outcome. The 5-year freedom from thromboembolic events after aortic valve replacement has been reported as 85.8% ± 2.5%, 16 88% ± 3%, 17 and 94.7% ± 1% 18 for the SJM valve, and 85.9% ± 3.5% 16 and 97.8% 19 for the CM valve. Some studies found the CM valve to be significantly associated with thromboembolism, especially in the mitral position. 8 In our study, despite no valve thrombosis detected in the SJM group, we found no statistically significant dif- TABLE V. Causes of Death Cause St. Jude Medical CarboMedics Hospital death Cardiac 1 1 Respiratory 0 1 Multi-organ failure 0 1 Late death Cardiac 6 5 Sudden 0 1 Embolism 1 1 Unknown 1 1 TABLE IV. Operative and Postoperative Characteristics Variable St. Jude Medical CarboMedics P Value CPB time (min) 87.8 ± 25.4 85.7 ±25.6 NS ACC time (min) 60.5 ± 19.2 58.7 ±20.1 NS Valve size 23.8 ± 2.0 23.4 ± 1.7 NS Low cardiac output 17 (23.6%) 24 (25.5%) NS Pacemaker use 3 (3.8%) 3 (3.2%) NS Fig. 2 Freedom from thromboembolic complications with the St. Jude Medical and CarboMedics valves. Intensive care 2.2 ± 0.7 2.6 ± 2.7 NS stay (day) Hospital stay (day) 8.2 ± 2.4 7.5 ± 1.6 NS Reexploration 2 (2.5%) 3 (3.2%) NS ACC = aortic cross-clamp; CPB = cardiopulmonary bypass; NS = not significant Fig. 3 Freedom from anticoagulant-related bleeding with the St. Jude Medical and CarboMedics valves. Fig. 1 Actuarial survival rates with the St. Jude Medical and CarboMedics valves. ference in freedom from thromboembolism (87.7% for SJM vs 83.0% for CM). The average INR levels in this study were 2.7 ± 0.8 and 2.4 ± 1.2 in the SJM and CM groups. The patient who had a thrombosed valve in the CM group failed to comply with warfarin Texas Heart Institute Journal St. Jude and CarboMedics Valves in the Aortic Position 157

hemorrhage after aortic valve placement with the SJM valve to be 89% ± 2%, 17 96.5% ± 1.5%, 20 and 99% ± 1% 21 at 5 years; after aortic valve placement with the CM valve, it was 93% ± 2% 8 at 5 years and 96.4% ± 1.6% at 10 years. 22 Our results were similar to these and reached no statistical significance. In evaluating isolated aortic valve replacement with SJM and CM valves, we detected no late survival advantage of one type of valve over the other. At 130 months, the actuarial survival rates in the current study were 75.9% with the SJM valves and 69.8% with the CM valves. There are few reports on the long-term clinical comparison of these valves, but our results are comparable with those: long-term survival with the SJM valve has ranged from 42% to 81%, and with the CM valve it has ranged from 77.6% to 85.1%. 3,4,21,22 Our results indicate that the standard SJM and CM prostheses offer similar excellent clinical performance in the aortic position. Fig. 4 Preoperative and postoperative New York Heart Association functional class in patients undergoing aortic valve replacement. SJM = St. Jude Medical group; CM = CarboMedics group therapy because of a mental disorder. Disparities in results indicate that the specific characteristics of each patient and the method of anticoagulation may play a greater role in thromboembolism than does the type of mechanical prosthesis. 1 Anticoagulant-related hemorrhage is another major problem in patients who receive mechanical heart valves. Previous studies have reported freedom from References 1. Bernal JM, Rabasa JM, Gutierrez-Garcia F, Morales C, Nistal JF, Revuelta JM. The CarboMedics valve: experience with 1,049 implants. Ann Thorac Surg 1998;65:137-43. 2. de Luca L, Vitale N, Giannolo B, Cafarella G, Piazza L, Cotrufo M. Mid-term follow-up after heart valve replacement with CarboMedics bileaflet prostheses. J Thorac Cardiovasc Surg 1993;106:1158-65. 3. Baudet EM, Puel V, McBride JT, Grimaud JP, Roques F, Clerc F, et al. Long-term results of valve replacement with the St. Jude Medical prosthesis. J Thorac Cardiovasc Surg 1995;109:858-70. 4. Zellner JL, Kratz JM, Crumbley AJ 3rd, Stroud MR, Bradley SM, Sade RM, Crawford FA Jr. Long-term experience with the St. Jude Medical valve prosthesis. Ann Thorac Surg 1999;68:1210-8. 5. Craver J. CarboMedics Prosthetic Heart Valve. Eur J Cardiothorac Surg 1999;15 Suppl 1:S3-11; discussion S39-43. 6. Copeland JG 3rd. An international experience with the CarboMedics prosthetic heart valve. J Heart Valve Dis 1995;4: 56-62. 7. Akins CW. Results with mechanical cardiac valvular prostheses. Ann Thorac Surg 1995;60:1836-44. 8. Rosengart TK, O Hara M, Lang SJ, Ko W, Altorki N, Krieger KH, Isom OW. Outcome analysis of 245 CarboMedics and St. Jude valves implanted at the same institution. Ann Thorac Surg 1998;66:1684-91. 9. Edmunds LH Jr, Clark RE, Cohn LH, Grunkemeier GL, Miller DC, Weisel RD. Guidelines for reporting morbidity and mortality after cardiac valvular operations. The American Association for Thoracic Surgery, Ad Hoc Liaison Committee for Standardizing Definitions of Prosthetic Heart Valve Morbidity. Ann Thorac Surg 1996;62:932-5. 10. Jamieson WR, Miyagishima RT, Grunkemeier GL, Germann E, Henderson C, Fradet GJ, et al. Bileaflet mechanical prostheses performance in mitral position. Eur J Cardiothorac Surg 1999;15:786-94. 11. Jamieson WR, Munro AI, Miyagishima RT, Grunkemeier GL, Burr LH, Lichtenstein SV, Tyers GF. Multiple mechanical valve replacement surgery comparison of St. Jude Med- 158 St. Jude and CarboMedics Valves in the Aortic Position Volume 33, Number 2, 2006

ical and CarboMedics prostheses. Eur J Cardiothorac Surg 1998;13:151-9. 12. Chaudhuri N, Hickey MS, Spyt TJ. An unexplained cluster of thrombosed bileaflet mechanical heart valve prostheses. Ann Thorac Surg 1999;67:1542-3. 13. Ibrahim M, O Kane H, Cleland J, Gladstone D, Sarsam M, Patterson C. The St. Jude Medical prosthesis. A thirteenyear experience. J Thorac Cardiovasc Surg 1994;108:221-30. 14. DiSesa VJ, Collins JJ Jr, Cohn LH. Hematological complications with the St. Jude valve and reduced-dose Coumadin. Ann Thorac Surg 1989;48:280-3. 15. Aagaard J, Tingleff J, Andersen PV, Hansen CN. Fourteen years experience with the CarboMedics valve in young adults with aortic valve disease. J Heart Valve Dis 2003;12: 81-6. 16. Masters RG, Helou J, Pipe AL, Keon WJ. Comparative clinical outcomes with St. Jude Medical, Medtronic Hall and CarboMedics mechanical heart valves. J Heart Valve Dis 2001;10:403-9. 17. Czer LS, Chaux A, Matloff JM, DeRobertis MA, Nessim SA, Scarlata D, et al. Ten-year experience with the St. Jude Medical valve for primary valve replacement. J Thorac Cardiovasc Surg 1990;100:44-55. 18. Wang SS, Chu SH, Tsai CH, Lin FY. Clinical use of CarboMedics and St. Jude Medical valves. Artif Organs 1996; 20:1299-303. 19. Onoda K, Suzuki T, Kanemitsu N, Yuasa U, Takao M, Shimono T, et al. Long-term results of valve replacement with the CarboMedics prosthetic heart valve. Artif Organs 2002: 26;479-82. 20. Lim KH, Caputo M, Ascione R, Wild J, West R, Angelini GD, Bryan AJ. Prospective randomized comparison of CarboMedics and St Jude Medical bileaflet mechanical heart valve prostheses: an interim report. J Thorac Cardiovasc Surg 2002;123:21-32. 21. Tominaga R, Kurisu K, Ochiai Y, Tomita Y, Masuda M, Morita S, Yasui H. A 10-year experience with the Carbomedics cardiac prosthesis. Ann Thorac Surg 2005;79: 784-9. 22. Masters RG, Pipe AL, Walley VM, Keon WJ. Comparative results with the St. Jude Medical and Medtronic Hall mechanical valves. J Thorac Cardiovasc Surg 1995;110:663-71. Texas Heart Institute Journal St. Jude and CarboMedics Valves in the Aortic Position 159