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Ann Thorac Surg 2004;78:67-72
© 2004 The Society of Thoracic Surgeons

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Original article: cardiovascular

Risk of repeat mitral valve replacement for failed mitral valve prostheses

^a Division of Cardiovascular Surgery, Mayo Clinic, Rochester, Minnesota, USA

Accepted for publication February 3, 2004.

^* Address reprint requests to Dr Sundt, Division of Cardiovascular Surgery, Mayo Clinic, 200 First St SW, Rochester, MN 55905, USA
e-mail: sundt.thoralf{at}mayo.edu

Presented at the Fiftieth Annual Meeting of the Southern Thoracic Surgical Association, Bonita Springs, FL, Nov 13–15, 2003.

	Abstract

Top Abstract Introduction Patients and methods Results Comment Acknowledgments Discussion References

 
BACKGROUND: Advances in tissue prosthetic valve design and manufacturing have stimulated renewed interest in the use of biological valves in younger patients. This approach, however, risks reoperation. We therefore reviewed our recent experience with repeat mitral valve replacement to better define its contemporary risks.

METHODS: Using a computerized database, we identified and compared 106 patients undergoing repeat mitral valve replacement with 562 control patients undergoing primary mitral valve replacement between January 1993 and December 2000 at our institution.

RESULTS: There were no significant differences between repeat and primary surgery groups with respect to age (mean 66 ± 12 vs 64 ± 13 years), gender distribution (women 65% vs 64%), preoperative functional class, ejection fraction, or active endocarditis (6.6% vs 3.4%). The indication for reoperation in the repeat group was structural dysfunction in 49 patients (46%), paravalvular leak in 21 patients (20%), nonstructural dysfunction in 11 patients (10%), and progression of other native valve disease in 8 patients (8%). Prior prostheses were mechanical in 46 patients (43%). Mean time to reoperation was 11.5 ± 7.1 years. There were 5 deaths out of 106 patients in the repeat group (4.7%) and there were 23 deaths out of 562 patients in the control group (4.1%) (p = NS). Multivariate analysis identified prior myocardial infarction (p = 0.014, odds ratio 2.9) and nonelective surgical status (p = 0.004, odds ratio 2.3) as significant predictors of operative mortality.

CONCLUSIONS: The risk of repeat mitral valve replacement was low suggesting that there should be less reluctance to recommend patients choose a bioprosthesis over a mechanical prosthesis. Given the expected durability of current designs, bioprosthetic use may be explored in younger patients without subjecting those individuals to excessive risk.

	Introduction

Top Abstract Introduction Patients and methods Results Comment Acknowledgments Discussion References

 
Prosthetic valve replacement requires patients and physicians to choose between two imperfect options; mechanical valves demand the patient attend to careful anticoagulation while bioprosthetic valves risk degeneration. In addition, for mechanical valvular prostheses there continues to be appreciable rates of thrombosis, thromboembolism, and anticoagulant related hemorrhage [1–3]. Manufacturers have made design modifications in bioprosthetic valves to improve their hemodynamic function [4, 5] and durability [6, 7] and now encourage their use in younger patients. This policy, however, hazards reoperation in some patients because of structural deterioration. We therefore examined the contemporary risk of replacement for failed mitral valve prostheses.

	Patients and methods

Top Abstract Introduction Patients and methods Results Comment Acknowledgments Discussion References

 
Study group
We identified all cardiac surgical patients who had a primary or repeat mitral valve replacement (MVR) at the Mayo Clinic Rochester from January 1993 to December 2000 using a prospective computerized registry maintained in accordance with the Society of Thoracic Surgery guidelines [8]. All operative reports for the repeat MVR group were reviewed to ensure that this group included only secondary valve replacements. Direct repair of paravalvular leak was not considered a repeat MVR. Concomitant valve replacements and coronary artery bypass procedures were included. Prior commissurotomy, valvuloplastic procedures, and coronary revascularization were not considered first operations. Using these criteria, 562 patients undergoing primary MVR and 106 patients having repeat MVR constituted the study group.

Definitions
Operative mortality was defined as death occurring within 30 days of operation or before hospital discharge. Any abnormality resulting in stenosis or regurgitation of the mitral valve that was not intrinsic to the valve itself, such as pannus ingrowth, trauma, or surgical error, was termed nonstructural dysfunction. In contrast, structural dysfunction was defined as a change in valve function due to an intrinsic abnormality causing stenosis or regurgitation, such as calcification and leaflet tears.

Patients with preoperative serum creatinine greater than or equal to 2.0 mg/dl were considered to have renal insufficiency whereas postoperative renal insufficiency was defined as a creatinine level greater than or equal to 2.0 mg/dl or a doubling of the preoperative creatinine level. Requirement for dialysis was considered a complication of surgery only if preoperative renal function was normal. Patients requiring intravenous nitrate therapy in the absence of myocardial infarction were considered to have unstable angina. Myocardial infarction was defined by the presence of two of the following four criteria: (i) prolonged (> 20 minutes) typical chest pain not relieved by rest and/or nitrates, (ii) enzyme (creatinine kinase myocardial band [MB] fraction, lactate dehydrogenase subtype 1, and troponin T) level elevation, (iii) any wall motion abnormality detected by echocardiography, ventriculogram, or multiple gated acquisition (MUGA), and (iv) serial electrocardiogram (ECG) with ST-T segment changes or pathologic Q waves. Operations were defined as emergencies if performed for cardiovascular instability requiring a procedure outside of normal operative schedule or if another patient was displaced from their scheduled operation. Operations were defined as urgent if patients had symptoms requiring hospitalization for evaluation and were too unstable to discharge before an operative procedure. Neurologic symptoms lasting less than 1 hour and neurologic deficits that resolved in less than 72 hours were termed transient neurologic deficits, whereas stroke was defined as a central neurologic deficit persisting for more than 72 hours. Gastrointestinal complications included gastrointestinal bleeding requiring transfusion or a change in anticoagulation protocol, cholecystitis requiring cholecystotomy drainage or surgical intervention, pancreatitis detected by elevated pancreatic enzymes, or ischemic or gangrenous bowel requiring surgical resection. Sternal wound infection required antibiotics, incision and drainage, or a positive wound culture.

Statistical analysis
Categorical factors were compared between groups using the Fisher exact test. For groups with severity classifications, such as mitral valve regurgitation, we based the p value on an absent versus present response. Logistic regression models were used to construct a multivariate model to predict operative mortality. A stepwise selection technique was used to identify factors for the final multivariate model. A p value of less than or equal to 0.05 was considered statistically significant.

	Results

Top Abstract Introduction Patients and methods Results Comment Acknowledgments Discussion References

 
The age distribution of patients undergoing mitral valve replacements in both the primary and repeat groups was similar. Demographic and clinical characteristics of the study groups are shown in Table 1. There was no difference between groups with respect to mean age, gender, or functional class. Although there was a trend for a higher incidence of endocarditis in the repeat group, this did not reach statistical significance. The repeat MVR group had a higher incidence of remote (> 2 weeks) stroke compared with the primary group, whereas peripheral vascular disease, coronary artery disease (CAD), and prior myocardial infarction were more common in the primary MVR group. The repeat MVR group had substantially more concomitant aortic valve disease.

Mitral valve replacement was approached by using a right thoracotomy in 3 patients (2.8%) in the repeat group and 13 patients (2.3%) in the primary group (p = 0.456). Additional operative characteristics are summarized in Table 2. When considering only isolated mitral valve replacements, the repeat MVR group had substantially longer aortic cross clamp times compared with the primary MVR, however cardiopulmonary bypass times were similar. The repeat MVR group had more concomitant aortic valve replacements, whereas the primary group underwent coronary artery bypass procedures more frequently. Tricuspid valve annuloplasties and replacements were performed more commonly in the repeat group and there was a trend toward more frequent insertion of intraaortic balloon pumps in the repeat group as compared with the primary group. Although approximately equal numbers of mechanical and bioprosthetic valves were explanted, more mechanical valves were inserted at the repeat operation.

Among patients undergoing repeat operations, those undergoing reoperation for failed mechanical mitral valves differed from those with failed bioprosthetic valves in a number of respects. Patients with prior mechanical valves tended to be younger than patients with prior bioprosthetic valves. Despite this younger age, remote stroke was more common in patients with prior mechanical valves (Table 4). The mean interval from the time of implantation to reoperation was quite similar for the mechanical and bioprosthetic groups (11.1 years vs 10.2 years, p = 0.944). This finding persisted when age at the time of reoperation was taken into account (p = 0.45, Fig 1).

View larger version (20K): [in this window] [in a new window]   Fig 1. Median interval to reoperation for failed mitral valve prostheses.

	Comment

Top Abstract Introduction Patients and methods Results Comment Acknowledgments Discussion References

 
The principle finding of this study was the low operative mortality for repeat mitral valve replacement in a contemporary series. The risks were, in fact, neither statistically nor clinically different from those for primary MVR. Although there is undoubtedly some impact of selection bias on this observation, the contemporary risk of repeat MVR is less than one might expect. A secondary observation is that the type of explanted prosthesis—mechanical versus bioprosthetic—did not effect operative mortality for repeat mitral valve replacement.

These data suggest that the contemporary risk of repeat MVR is less than the 7%–12% previously reported [9–13], which is similar to Cohn and colleagues [11] who reported a mortality rate of only 6% at their institution for repeat MVR from 1989–1992. Indeed, a previous study from our own institution of operations performed in the 1970s and 1980s reported an operative mortality of 19.6% for primary mitral valve replacement [10]. This reduction in risk may be due to improvements in operative technique and perioperative care. This discrepancy reinforces the value of a contemporary series in clinical decision making.

Prior studies have identified age [9, 12], male gender [9], New York Heart Association functional class [10, 12, 13], prosthetic endocarditis [14], renal insufficiency [9], previous aortic or tricuspid operations [12], type of mitral valve procedure (repair of periprosthetic leak, replacement vs valve-conserving operation) [12], and nonelective operation [9, 10, 12, 13] as notable predictors of operative mortality. We identified prior myocardial infarction and nonelective surgical status as substantial predictors for operative mortality. These differences in risk factors may be due to improvements in care that have neutralized these factors or because of relatively small numbers and the low event rate in our series.

The risk of degeneration of porcine xenograft valves [15–17] and bovine pericardial valves [18, 19] leads many physicians to advise their patients to accept a mechanical prosthesis with life-long anticoagulation. Intriguingly, despite the structural integrity of current mechanical valves, several large, prospective, randomized trials reported in the last decade have demonstrated survival and overall incidence of valve-related complications to be quite similar for mechanical and biological valves after 12 years of follow-up [20, 21]. An argument can be made, therefore, for the expanded use of second and third generation bioprosthetic valves even in younger patients because of the anticipated slower rate of structural deterioration and accordingly lower predicted reoperation rates compared with first generation bioprosthetic valves [22, 23]. The results of the current study support this philosophy.

Finally, we anticipated that the majority of repeat operations would be for degeneration of tissue valves. Our results demonstrate, however, that a considerable number of mechanical valves will require replacement as well. Additionally, during the same time period, 46 patients had direct repair of a paravalvular leak of which 38 were mechanical prostheses. Early mortality in this group was 1 out of 46 patients (2.2%). Without data on the total number of patients undergoing mechanical valve replacement we cannot address the rate of reoperation, however it is clear that the implantation of a mechanical valve does not eliminate this risk. Reported reoperation rates for mechanical mitral prostheses range from 1%–8% at 5 years and 2%–16% at 10 years [2].

This study suffers from the limitations inherent in all retrospective studies including subtle selection bias for entry, particularly into the reoperative group. In addition, given the relatively small sample size and low event rate in both groups, we are limited in our ability to analyze risk factors. Despite this power limitation, the operative mortality for each group was remarkably similar. The clinical significance of this difference is likely to be small. Consideration was made to extend the study interval back in time, however we felt that it was more important to focus on the contemporary results. We conclude, therefore, that in the current era there should be less reluctance to recommend and implant new generation bioprosthetic mitral valves in younger patients because of the risk of reoperation.

	Acknowledgments

Top Abstract Introduction Patients and methods Results Comment Acknowledgments Discussion References

 
We thank Ms. Judy R. Lenoch for her assistance with the computerized database search.

	Discussion

Top Abstract Introduction Patients and methods Results Comment Acknowledgments Discussion References

 
DR JOHN H. CALHOON (San Antonio, TX): Dr Potter, that was a nice presentation, and very well done. I have a question. Do you have any data on what percentage of your original mitral valve replacements were mechanical versus tissue, in other words, how many as a percentage of the mechanical valves implanted, what number failed and had to be reimplanted versus the bioprosthetic valves?

DR POTTER: Dr Calhoon, thank you for the interesting question. We cannot answer that question accurately since not all of the patients who underwent repeat mitral valve replacements had their primary replacement at the Mayo Clinic. Also, we do not know the number of patients who had their primary mitral valve replacement at the Mayo Clinic, and went on to have a repeat mitral valve replacement at a different institution.

	References

Top Abstract Introduction Patients and methods Results Comment Acknowledgments Discussion References

 

1. Edmunds L.H. Thrombotic and bleeding complications of prosthetic heart valves. Ann Thorac Surg 1987;44:430-445.[Abstract]
2. Akins C.W. Results with mechanical cardiac valvular prostheses. Ann Thorac Surg 1995;60:1836-1844.[Abstract/Free Full Text]
3. Rahimtoola S.H. Choice of prosthetic heart valves for adult patients. J Am Coll Cardiol 2003;19:41.
4. De Feo M., Renzulli A., Onorati F., Della Corte A., Dialetto G., Covino F.E., et al. Initial clinical and hemodynamic experience with Edwards MIRA mechanical bileaflet valve. J Cardiovasc Surg 2003;44:25-30.[Medline]
5. Chambers J., Ely J.L. Early postoperative echocardiographic hemodynamic performance of the On-X prosthetic heart valve: a multicenter study. J Heart Valve Dis 1998;7:569-573.[Medline]
6. Jamieson W.R., Burr L.H., Munro A.I., Miyagishima R.T. Carpentier-Edwards standard porcine bioprosthesis: a 21-year experience. Ann Thorac Surg 1998;66:S40-43.
7. Legarra J.J., Llorens R., Catalan M., Segura I., Trenor A.M., de Buruaga J.S., et al. Eighteen-year follow up after Hancock II bioprosthesis insertion. J Heart Valve Dis 1999;8:16-24.[Medline]
8. Edmunds L.H., Clark R.E., Cohn L.H., Grunkemeier G.L., Miller D.C., Weisel R.D. Guidelines for reporting morbidity and mortality after cardiac valvular operations. Ann Thorac Surg 1996;62:932-935.[Abstract/Free Full Text]
9. Akins C.W., Buckley M.J., Daggett W.M., Hilgenberg A.D., Vlahakes G.J., Torchiana D.F., et al. Risk of reoperative valve replacement for failed mitral and aortic bioprostheses. Ann Thorac Surg 1998;65:1545-1551.[Abstract/Free Full Text]
10. Husebye D.G., Pluth J.R., Piehler J.M., Schaff H.V., Orszulak T.A., Puga F.J., et al. Reoperation on prosthetic heart valves. An analysis of risk factors in 552 patients. J Thorac Cardiovasc Surg 1983;86:543-552.[Abstract]
11. Cohn L.H., Aranki S.F., Rizzo R.J., Adams D.H., Cogswell K.A., Kinchla N.M., et al. Decrease in operative risk of reoperative valve surgery. Ann Thorac Surg 1993;56:15-20.[Abstract]
12. Lytle B.W., Cosgrove D.M., Taylor P.C., Gill C.C., Goormastic M., Golding L.R., et al. Reoperations for valve surgery: perioperative mortality and determinants of risk for 1,000 patients, 1958–1984. Ann Thorac Surg 1986;42:632-643.[Abstract]
13. Piehler J.M., Blackstone E.H., Bailey K.R., Sullivan M.E., Pluth J.R., Weiss N.S., et al. Reoperation on prosthetic heart values. Patient-specific estimates of in-hospital events. J Thorac Cardiovasc Surg 1995;109:30-48.[Abstract/Free Full Text]
14. Mazzucco A., Milano A., Mazzaro E., Bortolotti U. Reoperation in patients with a bioprosthesis in the mitral position: indications and early results. J Heart Valve Dis 1993;2:646-648.[Medline]
15. Glower D.D., White W.D., Hatton A.C., Smith L.R., Young W.G., Wolfe W.G., et al. Determinants of reoperation after 960 valve replacements with Carpentier-Edwards prostheses. J Thorac Cardiovasc Surg 1994;107:381-392.[Abstract/Free Full Text]
16. Jamieson W.R., Burr L.H., Tyers G.F., Munro A.I. Carpentier-Edwards standard and supra-annular porcine bioprostheses: 10 year comparison of structural valve deterioration. J Heart Valve Dis 1994;3:59-65.[Medline]
17. Sarris G.E., Robbins R.C., Miller D.C., Mitchell R.S., Moore K.A., Stinson E.B., et al. Randomized, prospective assessment of bioprosthetic valve durability. Hancock versus Carpentier-Edwards valves. Circulation 1993;88:II55-64.
18. Moggio R.A., Pooley R.W., Sarabu M.R., Christiana J., Ho A.W., Reed G.E. Experience with the Mitroflow aortic bioprosthesis. J Thorac Cardiovasc Surg 1994;108:215-220.[Abstract/Free Full Text]
19. Grabenwoger M., Grimm M., Leukauf C., Szeles C., Feichtinger E., Muller M.M., et al. Failure mode of a new pericardial valve prosthesis (Sorin Pericarbon). A morphological study. Eur J Cardiothorac Surg 1994;8:470-476.[Abstract]
20. Hammermeister K.E., Sethi G.K., Henderson W.G., Oprian C., Kim T., Rahimtoola S. A comparison of outcomes in men 11 years after heart-valve replacement with a mechanical valve or bioprosthesis. Veterans Affairs Cooperative Study on Valvular Heart Disease. N Engl J Med 1993;328:1289-1296.[Abstract/Free Full Text]
21. Bloomfield P., Wheatley D.J., Prescott R.J., Miller H.C. Twelve-year comparison of a Bjork-Shiley mechanical heart valve with porcine bioprostheses. N Engl J Med 1991;324:573-579.[Abstract]
22. Akins C.W., Carroll D.L., Buckley M.J., Daggett W.M., Hilgenberg A.D., Austen W.G. Late results with Carpentier-Edwards porcine bioprosthesis. Circulation 1990;82:IV65-74.
23. Jamieson W.R., Rosado L.J., Munro A.I., Gerein A.N., Burr L.H., Miyagishima R.T., et al. Carpentier-Edwards standard porcine bioprosthesis: primary tissue failure (structural valve deterioration) by age groups. Ann Thorac Surg 1988;46:155-162.[Abstract]

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This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Thoralf M. Sundt, III Kenton J. Zehr Joseph A. Dearani Richard C. Daly Charles J. Mullany Christopher G. A. McGregor Francisco J. Puga Hartzell V. Schaff Thomas A. Orszulak Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Potter, D. D. Articles by Orszulak, T. A. Search for Related Content PubMed PubMed Citation Articles by Potter, D. D. Articles by Orszulak, T. A. Related Collections Valve disease