Ann Thorac Surg 2003;76:1939-1943
© 2003 The Society of Thoracic Surgeons
Original article: cardiovascular
Long-term results of reoperative mitral valve surgery in patients with rheumatic disease
Katsuhiko Matsuyama, MDa*,
Masahiko Matsumoto, MDa,
Takaaki Sugita, MDa,
Junichiro Nishizawa, MDa,
Yujiro Kawansihi, MDa,
Kyokuu Uehara, MDa
a Department of Cardiovascular Surgery, Tenri Hospital, Tenri, Nara, Japan
Accepted for publication May 12, 2003.
* Address reprint requests to Dr Matsuyama, Department of Cardiovascular Surgery, Tenri Hospital, 200 Mishima, Tenri, Nara 632-8552, Japan
e-mail: kmatsuy{at}f3.dion.ne.jp
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Abstract
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BACKGROUND: Reoperative (redo) mitral valve surgery is still a continuing challenge to surgeons. The aim of this study was to detect the factors that affect late mortality or morbidity after redo mitral valve surgery in patients with rheumatic disease.
METHODS: Between May 1983 and February 2003, 92 patients who underwent redo mitral valve surgery for rheumatic disease were enrolled. Risk factors influencing survival or cardiac events were investigated with univariate analysis and a Cox model.
RESULTS: Operative mortality rate was 4.2%. Kaplan-Meier actuarial analysis demonstrated an 84.7% 5-year, a 69.5% 10-year, and a 65.9% 15-year survival. Multivariate analysis demonstrated that age at surgery and preoperative New York Heart Association (NYHA) class were found to be independent predictors of late deaths, and that higher age, advanced NYHA class, and previous mitral valve replacement were independent predictors of cardiac events.
CONCLUSIONS: Redo mitral valve surgery can be achieved with low early mortality. However, long-term results of redo mitral surgery are not necessarily satisfactory in patients with preoperative advanced NYHA class or with a previous mechanical heart valve, and especially in 60 years or older age.
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Introduction
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Operative mortality of open mitral commissurotomy (OMC) or mitral valve replacement (MVR) for rheumatic disease has remarkably decreased recently, and the long-term results are also excellent. However, cases requiring reoperation due to restenosis of mitral valve or prosthetic valve dysfunction are increasing. Reoperation itself has a risk, and the early and late results are not necessarily satisfying because of the persistent left ventricular (LV) dysfunction [1]. We reviewed our experiences with reoperative (redo) mitral valve surgery for rheumatic disease over the last 20 years, and assessed the risk factors that affect late survival or long-term outcome.
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Patients and methods
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A total of 92 patients underwent redo mitral valve surgery for rheumatic disease from May 1983 through February 2003. One patient was excluded from this study because of a lost followup. There were 58 patients of OMC and 213 of MVR for rheumatic valve disease during the same period. The preoperative and operative characteristics of the patients were summarized in Table 1.
The mean age of the patients at the time of operation was 56.4 ± 10.4 years (range, 33 to 74). Preoperatively, 12 patients (13%) were in the New York Heart Association (NYHA) functional class II, 73 (79%) were in class III, and 7 (8%) were in class IV. Previous mitral surgery was OMC in 62 patients (67%) and MVR in 30 (33%). The prosthetic mitral valve used at previous mitral surgery was Omniscience in 12 patients, Starr-Edwards in 6, Lillehei-Kaster in 5, Bjork-Shiley in 2, and St. Jude Medical in 4. There were no biological prostheses. Reoperative surgery included re-repair in 9 patients (10%), MVR in 54 (59%), and re-MVR in 29 (32%). The prosthetic valve used at reoperative mitral valve surgery was St. Jude Medical valve in all patients. The mean interval to reoperation was 14.0 ± 6.9 years (range, 0.0 to 31.0). Surgical indications were restenosis after OMC in 61 patients (66%), relative valve area stenosis of prosthetic valve due to thrombosis or pannus formation in 22 (24%) (Omniscience, 7; Starr-Edwards, 6; Lillehei-Kaster, 5; Bjork-Shiley, 2; and St. Jude Medical, 2), infective endocarditis in 5 (5%) (native mitral valve, 1; Omniscience, 3; St. Jude Medical, 1), paravalvular leak in 3 (3%) (Omniscience, 2; St. Jude Medical, 1), and ruptured ventricle in 1 (1%). Complications were defined in accordance with the published guidelines for reporting valve related morbidity and mortality after cardiac valvular operation [2]. For cardiac events analysis, events were defined as all cardiac deaths, sudden deaths, valve-related complication, and congestive heart failure.
Continuous variables were provided as mean ± SD. Categorical data were analyzed univariately by 
2 test or Fischer's exact test. Actuarial survival and freedom from cardiac events were calculated by the Kaplan-Meier method, and were compared using the log-rank statistic. To identify significant independent risk factors influencing late mortality or cardiac events, all factors with a significance less than 0.1 were entered into multivariate analysis. Risk ratio and 95% confidence intervals were calculated using a Cox proportional hazards model. A p value of less than 0.05 was considered statistically significant.
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Results
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All redo operations were carried out through a median sternotomy. Of 92 patients, re-repair was performed in 9 patients (10%), MVR in 54 (59%), and re-MVR in 29 (31%). An operative mortality rate was 4.2% (4 patients including one ruptured ventricle). The mean followup was 7.8 ± 5.3 years (range, 0.1 to 19.8). Eighteen patients died during the followup. The cause of deaths was cardiac failure in 4 patients, sudden death in 2, anticoagulation related complication in 5 (hemorrhage in 3, embolism in 2), noncardiac in 7 (cancer in 4, respiratory failure in 1, liver failure in 1, traffic accident in 1). Kaplan-Meier actuarial analysis in redo patients demonstrated an 84.7% 5-year, a 69.5% 10-year, and a 65.9% 15-year survival (Fig 1).
The survival rate in patients who underwent reoperative surgery was significantly lower as compared with that in patients who had not required reoperative surgery during the same followup (p < 0.0001). Univariate analyses were performed separately for over all survival and cardiac events (Table 2).
Higher age, male sex, advanced NYHA class, and previous MVR were significantly related to lower survival rates. By multivariate analyses, the independent predictors of decreased long-term survival were higher age and advanced NYHA class (Table 3).
There were 11 valve-related complications including deaths. Brain infarction occurred in 7 patients (2 deaths), intracranial bleeding in 3 (3 deaths), gastrointestinal bleeding in 1. There were no patients requiring a third operation for valve related disease during the followup. No variables could be found to be significant in multivariate analysis of valve related complications.
During the followup, 25 patients (28%) were readmitted for congestive cardiac failure.
Freedom from cardiac events including cardiac deaths, sudden deaths, valve related complications, and congestive heart failure were 72.7% 5-year, 62.2% 10-year, and 52.6% 15-year (Fig 2).
Higher age, advanced NYHA class, previous MVR, atrial fibrillation, lower left ventricular ejection fraction (LVEF), huge left atrium, and combined aortic valve replacement were significant determinants of cardiac events (Table 4).
The independent predictors of cardiac events were higher age, advanced NYHA class, and previous MVR (Table 5).
At last followup, 58 of 69 survivors were in NYHA class I or II, and 11 patients were in III or IV. However, patients whose age at surgery was more than 60 had a significantly higher NYHA class than patients whose age was less than 60 (p < 0.0001) (Table 6).
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Comment
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OMC in rheumatic patients provides an excellent long-term survival rate. However, some patients require reoperation due to restenosis [3]. On the other hand, in patients with a mechanical valve, reoperation occurs due to valve thrombosis or pannus formation, paravalvular leak, and endocarditis [1, 4, 5]. While the risk of reoperative mitral valve surgery has been reported to be 10% [6], it is important to identify the risk factors of late mortality or morbidity.
Although Blackstone and Kirklin reported a shorter life expectancy for patients undergoing reoperation [7], our results showed a low operative mortality rate of 4.2%. Our study demonstrated that higher age and advanced NYHA class were independent risk factors of lower survival rate. Many observations have reported that advanced NYHA had an independent predictor for mortality on reoperation in prosthetic valve recipients [1, 4, 5]. On the other hand, lower LVEF was not a significant risk factor of late results in our study (because there might be a lower percentage of patients with lower LVEF: LVEF of less than 50% in 14% patients [13/92] and LVEF of less than 40% in only 2% patients [2/92]). Several studies have been reported on patient age as a high risk for both mortality and morbidity. The operative mortality of redo MVR at over the age of 70 is 14% [8]. Parsonnet and colleagues predict an operative mortality of at least 17% for patients more than 70 undergoing redo valve surgery [9]. Our study demonstrated that patient age more than 60 had significantly poorer long-term survival, although operative mortality was low.
This study has also focused on late morbidity. During the followup, 25 patients (28%) were readmitted for congestive cardiac failure. Among risk factors, higher age, previous MVR, and preoperative advanced NYHA class were independent risk factors in multivariate analyses. Of these risk factors, patient age is the most significant risk factor of cardiac events. Moreover, almost one-third of the survivors whose age at surgery was more than 60 were in NYHA class III or IV. It was concluded that these patients had no benefit in a quality of life even after redo surgery.
The long-term existence of a prosthetic mechanical valve may provide greater impact to deteriorate cardiac function, especially in patients with a first-generation prosthetic valve. As the organic and irreversible myocardial damage in these patients has already occurred at redo surgery, cardiac dysfunction might be persistent and repeated congestive heart failure might have developed. In our institution, no biological valves have been used for mitral lesions due to the disadvantage of lesser durability. However, a bioprosthesis may provide a beneficial effect on a patient more than 60 who is in an advanced NYHA class, because our study showed that these patients tended to have a shorter life expectancy.
The limitations of our study are, first, its small size and retrospective design. Second, the patient cohort is confused by a variety of early generation valves, which not only had hemodynamically disadvantages but also had a tendency to pannus or thrombus formation, and the eligibility for entry was over a 20-year period. During this time there have been numerous advances in perioperative management, myocardial preservation, and operative techniques including the preservation of subvalvular apparatus. The influence of time of operation was not examined. Third, the patient group includes reoperation for progressive disease along with patients in who valve failure has resulted from prosthetic dysfunction and thrombosis. This category has nothing in common with the title except for the fact that they may have initially had rheumatic valve disease.
In conclusion, this retrospective study demonstrated that redo mitral valve surgery could be undergone with low perioperative mortality. However, long-term results of redo mitral surgery are not necessarily satisfied in patients with preoperative advanced NYHA class or previous mechanical heart valve, and especially with age of 60 years or older.
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References
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Abstract
Introduction
