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Ann Thorac Surg 1999;68:2112-2118
© 1999 The Society of Thoracic Surgeons
a Department of Cardiac Surgery, Klinikum Großhadern, Ludwig-Maximilians-University, Munich, Germany
Address reprint requests to Dr Detter, Department of Cardiac Surgery, Klinikum Großhadern, Ludwig-Maximilians-University, D-81366 Munich, Germany
e-mail: cdetter{at}hch.med.uni-muenchen.de
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Abstract |
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Methods. From 1955 to 1977, 183 patients with mitral stenosis underwent mitral commissurotomy at our institution. Closed valvotomy was performed on 143 patients (group A) and open valvotomy on 40 patients (group B).
Results. Survival rates after 10, 20, and 30 years were 89%, 67.8%, and 49.1% in group A and 91.7%, 66.7%, and 45.9% in group B (p = not significant). The risk of late death increased significantly with an advanced preoperative New York Heart Association functional class, atrial fibrillation, higher age at operation, pre- or postoperative mitral regurgitation, and leaflet calcification. Forty-four patients in group A and 5 patients in group B required reoperation (p < 0.05). Independent predictors for reoperation in a multivariate analysis were a remaining postoperative mitral stenosis or regurgitation. A total of 68 patients showed valve-related complications. The linearized rate of valve-related morbidity and mortality was 2.1% per patient-years in group A versus 1.1% per patient-years in B (p < 0.01).
Conclusions. Long-term survival for open and closed commissurotomy are excellent, showing no difference between the groups. However, both the incidence of reoperation as well as valve-related morbidity and mortality were significantly lower after open commissurotomy. In well-selected patients with pure mitral stenosis and no leaflet calcification, open commissurotomy still remains a valid surgical option.
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Introduction |
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Several studies showed that mitral commissurotomy resulted in better long-term survival rates and fewer valve-related complications if compared to valve replacement [11, 12]. We report our experience of both open and closed mitral commissurotomy covering a 35-year follow-up period evaluating long-term survival rates, valve-related complications, as well as prognostic factors for early and late outcome.
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Patients and methods |
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TopAbstractIntroductionPatients and methodsResultsCommentReferences |
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Operative techniques
Closed valvotomy was performed through a left anterolateral thoracotomy. An incision was made in the left atrial appendage, followed by insertion of the right index finger into the left atrium. The first 13 patients of this series underwent digital valvotomy; since 1960, however, predominantly a Tubbs or a Dubost transventricular dilator was used. A pursestring suture was placed at the apex of the left ventricle and the dilator was subsequently passed through the apical ventriculotomy to the mitral valve orifice. The dilator was then positioned across the mitral valve orifice by palpation and opened one to four times.
Open valvotomy was performed through a median sternotomy or a right lateral approach. Operative management included cardiopulmonary bypass, a bubble oxygenator, moderate systemic hypothermia (28°C to 34°C) and induced ventricular fibrillation; cardioplegia was not given. For myocardial protection, cold saline solution was applied topically. The aorta was cross-clamped and the left atrium was opened and examined for the presence of a thrombus. Fused mitral commissures were incised widely with attention being paid to avoid valve regurgitation. The open procedure was associated with other maneuvers including thrombectomy in 4 patients, decalcification in 3, splitting of fused chordae tendineae and papillary muscles in 5, and mitral annuloplasty using the Wooler technique in 3 patients. Mean duration of cardiopulmonary bypass was 40 ± 38 minutes, the aortic cross-clamp time was 18 ± 16 minutes. Mitral valve competence was confirmed by intraventricular injection of saline solution. After operation, the result was controlled by hemodynamic pressure measurements.
Anticoagulation
In the early postoperative period, heparin was used prophylactically to prevent thrombosis or emboli. In patients with sinus rhythm, anticoagulation was discontinued after hospital discharge. All patients with postoperative atrial fibrillation (35.9%) received long-term oral anticoagulation therapy with phenprocoumon.
Follow-up
The patients’ operative records were reviewed retrospectively. Survival and follow-up information was acquired by questionnaires and telephone interviews with patients, relatives, and family practitioners. A clinical examination including echocardiography and electrocardiogram was performed at our institution on identified not reoperated survivors. Valve function, valve morphology, transvalvular gradients, myocardial function, myocardial thickness, and the diameter of the atria and ventricles were determined. The functional status was assigned according to the NYHA. Mean follow-up time was 19.9 ± 11.3 years (median, 23.9 years; range, 0 to 36.2 years) in group A and 17.6 ± 8.9 years (median, 20.6 years; range, 0 to 35.8 years) in group B. Ten patients (7.0%) in group A and 1 patient (2.5%) in group B were lost to follow-up studies after hospital discharge. Follow-up was complete in 94% of the patients representing a total of 3,544 patient-years (group A, 2,839 patient-years; group B, 705 patient-years).
The results of the operations performed are reported in accordance with the recommendations of the Ad Hoc Liaison Committee in "Guidelines for Reporting Morbidity and Mortality After Cardiac Valvular Operations [13]."
Statistical analysis
Continuous data were analyzed using the Mann-Whitney U test, categorical data using the 
2 test. Values were expressed as mean ± standard deviation. Long-term survival and freedom from complications were calculated by the Kaplan-Meier method. These data were expressed as means ± standard error of the mean. Univariate analyses were carried out by means of log-rank statistics, followed by a multivariate analysis using the Cox regression model. The variables included in the model were age, gender, operative year, preoperative NYHA class, preoperative cardiac medication, emergency operation, presence of left atrial thrombus, preoperative thromboembolism and atrial fibrillation, preoperative left ventricular enlargement, preoperative pulmonary vascular resistance, preoperative and postoperative mitral valve area and mitral regurgitation, leaflet calcification, operative technique (open versus closed), and all valve-related complications. Probability values less than 0.05 were considered significant. Statistical analysis was performed using the SPSS statistical software package 8.0 for Windows (SPSS Inc, Chicago, IL).
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Results |
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Among the clinical variables tested we identified the following significant risk factors for early mortality: advanced preoperative NYHA classification (p = 0.002), emergency operation (p < 0.001), atrial fibrillation (p = 0.004), presence of preoperative cardiac medication (p < 0.05), and left ventricular enlargement (p < 0.0001). Patients with an additional mitral regurgitation showed a trend for a higher early mortality rate (p < 0.07).
Late mortality
Among the 170 operative survivors 60 patients (45.1%, 2.1% per patient-year) died after closed procedures and 17 (45.9%, 2.4% per patient-year) after open procedures (p = not significant). The most frequent cause of late death was cardiac failure in 25 patients in group A and 10 patients in group B (Table 2). The Kaplan-Meier long-term survival curves for both groups are presented in Figure 1. Survival rates excluding early mortality after 10, 20, and 30 years were 89.0%, 67.8%, and 49.1% in group A and 91.7%, 66.7%, and 45.9% in group B (p = not significant). Median survival of all patients was 29 years (group A) versus 23.9 years (group B). There were no statistically significant differences between the groups.
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Valve-related complications
Valve-related mortality
There were 13 valve-related deaths in group A and 1 valve-related death in group B, representing a rate of 95.0%, 91.0%, and 85.0% in group A and 100%, 96.3%, and 96.3% in group B free of valve-related mortality at 10, 20, and 30 years (p = not significant). Valve dysfunction due to recurrent mitral valve stenosis was the main cause of valve-related death. One patient died at reoperation of the mitral valve and thromboembolism was the cause of death in another patient. The linearized rate was 0.46% per patient-years in group A versus 0.14% per patient-years in group B (p = not significant).
Thromboembolism
Postoperative thromboembolic events occurred in 9 patients in group A and in 2 patients in group B, corresponding to a linearized rate of 0.32% per patient-years in group A and 0.28% per patient-years in group B (p = not significant). Two of these patients were anticoagulated at the time of the event; neither of the patients died. The freedom from thromboembolism at 10, 20, and 30 years was 95.2%, 93.1%, and 89.7% for group A patients versus 97.4%, 96.6%, and 92.7% for group B patients (p = not significant).
Anticoagulant-related hemorrhage
Severe anticoagulant-related hemorrhage was observed in 9 patients in group A and in 2 patients in group B corresponding to a linearized rate of 0.32% per patient-years in group A and 0.28% in group B (p = not significant). Two patients died due to cerebral hemorrhage.
Endocarditis
Bacterial endocarditis occurred in 3 group A patients corresponding to a linearized rate of 0.11% per patient-years and none in group B. None of these patients died and one required reoperation.
Reoperation
Forty-four patients in group A and 5 patients in group B required reoperation of the mitral valve. The reoperation linearized rate was 1.55% per patient-years in A versus 0.71% per patient-years in B (p < 0.05). The mean interval between the first and second procedure was 15.7 ± 7.6 years (median, 16.3; range, 1.0 to 31.0 years) with no significant difference between the two groups. The main indication for reoperation was restenosis of the mitral valve in 28 group A patients (19.6%) and in 5 group B patients (12.5%). Fifteen group A patients (10.5%) and none in group B required reoperation for severe mitral regurgitation (p < 0.05). Of these, 5 patients showed a moderate mitral insufficiency immediately after the operation leading to early reoperation within the first 2 years in 2 patients (1.4%). One group A patient (0.7%) was reoperated due to mitral valve endocarditis. In 43 patients, a mitral valve replacement was performed. A repeated mitral commissurotomy was done in 3 patients, 2 patients needed balloon valvuloplasty and 1 patient required ring annuloplasty. Freedom from reoperation was 89.7% at 10 years, 73.5% at 20 years, and 49.5% at 30 years for group A patients and 93.9% at 10, 82.8% at 20 and 30 years for group B patients (Fig 3). One patient of group A (2.3%) and none of group B died during reoperation. Other cardiac procedures were necessary in 8 patients including aortic valve replacement in 2 patients, tricuspid valve operation in 3 patients, and coronary artery bypass grafting in 3 patients.
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Valve-related morbidity and mortality
This combination includes all valve-related deaths and all nonfatal valve-related morbid events. In total, 68 patients developed a valve-related complication. The linearized rate was 2.1% per patient-years in group A versus 1.1% per patient-years in group B (p < 0.01). Freedom from valve-related morbidity and mortality was 83.2% at 10 years, 63.7% at 20 years, and 38.4% at 30 years in group A and 87.9% at 10, and 73.5% at 20 and 30 years in group B.
Clinical follow-up in surviving patients
At the time of follow-up 82 patients were still alive. Of these, 30 patients who underwent closed commissurotomy and 15 patients who underwent open commissurotomy did not require reoperation. The follow-up period for all patients still alive and not requiring reoperation was between 17.8 and 34.5 years with a mean of 25.7 ± 4.9 years.
Nineteen patients (63.3%) who underwent closed commissurotomy and 10 patients (66.7%) who underwent open commissurotomy are currently in NYHA functional class I or II; 11 patients in group A and 5 patients in group B were in class III and none in class IV. There are no statistically relevant differences between the two groups. In group A, 55.6% and in group B, 73.7% of the patients are retired; 41.2% and 26.3%, respectively, are working, whereas only 3.2% of patients in group A are unable to work.
A standard electrocardiogram was used to provide additional information on cardiac rhythm. The electrocardiographic examination showed that 7 patients in group A and 4 patients in group B were in normal sinus rhythm. Atrial fibrillation was apparent in 21 patients (70%) of group A and in 10 patients (66.6%) of group B. A pacemaker was implanted in 2 patients of group A and in 1 patient of group B.
Echocardiographic results
Echocardiographic evaluations were performed in 44 of 45 surviving patients with no subsequent reoperation. The mean pressure gradients ranged between 3 and 18 mm Hg, with a mean of 5.5 mm Hg in group A and 5.4 mm Hg in group B. A significant mitral valve stenosis (mitral valve area, < 1.5 cm2) was seen in 13.3% of group A and 14.3% of group B patients. Severe valve incompetence (mitral valve insufficiency grade III) was present in 6.7% in group A and 7.1% in group B. Left ventricular myocardial function was measured as a function of fractional shortening and proved to be normal in 60% group A patients and 64.3% group B patients. All echocardiographic results are summarized in Table 3. There were no statistically relevant differences between the two groups.
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Comment |
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TopAbstractIntroductionPatients and methodsResultsCommentReferences |
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The present study showed excellent long-term results in both open and closed commissurotomy. The survival rates of our patients are within the range of other studies [10, 15, 19, 21]. Most studies showed no difference in survival rates between the closed and open technique [10, 16, 21]. Scalia and colleagues [21] showed identical survival rates using both techniques. Hickey and associates [10] were also able to demonstrate that the operative technique was not a risk factor for long-term survival. On the contrary, Nakano and colleagues [20] concluded that open commissurotomy was the procedure of choice, as survival rates and freedom from reoperation were preferable. The present study did not show any significant differences between the two groups in terms of long-term survival.
Factors that might contribute to the outcome of mitral commissurotomy and affect long-term survival have been evaluated in the present study. The risk of early and late death increased significantly with advanced preoperative NYHA class, preoperative atrial fibrillation, and higher age at the time of operation. Eguaras and associates [18] also demonstrated better results for early commissurotomy in young patients with sinus rhythm who are free of symptoms. Our group observed a significant impairment of long-term survival by additional pre- or postoperative mitral regurgitation and presence of leaflet calcification. Thus, this procedure is only indicated in patients presenting with no or mild mitral insufficiency and a flexible mitral valve free of calcification [18]. In accordance with other researchers we believe that mitral commissurotomy should be performed as early as possible to prevent progressive valve changes, which make reconstruction impossible [7, 18, 22]. Such early surgical intervention could possibly prevent serious secondary changes such as left atrial hypertrophy, atrial fibrillation, pulmonary hypertension, tricuspid insufficiency, and the risk of thromboembolism [11]. Thus, early operation and the proper selection of patients should be the major goal when performing a commissurotomy.
Reoperations of the mitral valve were more frequent in closed valvotomy than in the open technique, as demonstrated previously [8, 21, 22]. In part, this is attributable to postoperative mitral regurgitation, which is more likely to occur with the blind technique. In fact, 5 of 15 patients in group A who required reoperation for severe mitral regurgitation showed moderate mitral insufficiency immediately after operation. In contrast, none of group B patients needed reoperation for this reason. Here, the open technique might be favorable as mitral annuloplasty could be performed immediately if necessary. However, the main indication for reoperation was a restenosis of the mitral valve. Of these patients, 12 already had leaflet calcification and severe fusion of the subvalvular apparatus when first operated. Herrera and colleagues [19] stated that the incidence of restenosis is intimately connected with the fusion of the subvalvular apparatus and that a complete repair is a crucial factor to produce a satisfactory long-term result. Hickey and associates [10] showed that the severity of stenosis, the degree of leaflet calcification, and the degree of postcommissurotomy mitral incompetence were incremental risk factors for subsequent mitral valve procedure. In fact, risk analysis identified as significant risk factors for reoperation a remaining postoperative mitral stenosis, mitral regurgitation, and leaflet calcification.
Although commissurotomy of the valve is a more palliative surgical treatment, the median interval between the initial commissurotomy and reoperation was 16.3 years, without significant differences between the groups. This is probably the best proof of the effectiveness of mitral commissurotomy [10].
However, there was only one early death (2.1%) in patients who underwent reoperation. Because early mortality is low and long-term survival significantly improves after reoperation as shown in the multivariate analysis, second surgical interventions should be performed before serious secondary changes arise. If reoperation is necessary, valve replacement is the preferred method because of the severe pathologic changes of the valve [20, 21, 23].
The low incidence of valve-related complications with a thromboembolism rate of 0.32% per patient-years in group A and 0.28% per patient-years in group B is comparable with other publications [4, 6, 17]; it is furthermore significantly lower when compared to that of mitral valve replacements in the same period [11]. Over the years, anticoagulation therapy may be required because of atrial fibrillation, a history of thromboembolism, or an enlarged left atrium.
The valve-related morbidity and mortality proved to be low, supporting the view that a commissurotomy should be performed whenever indicated. In this study, valve-related morbidity and mortality was significantly lower in open commissurotomy when compared to the closed technique. This is mainly attributable to fewer reoperations and a lower rate of valve-related deaths in the open procedure. Farhat and colleagues [24] were able to show that after open commissurotomy hemodynamics improved to a greater extent than with closed commissurotomy and that open valvotomy is more effective in relieving the obstruction even when performed on selected patients with no preoperative mitral regurgitation.
The fact that almost two-thirds of the surviving patients are in NYHA class I or II and only 3.2% were unable to work demonstrates that for a follow-up period of 35 years after commissurotomy patients enjoy a good quality of life. Nearly a quarter of the patients involved are still in sinus rhythm. Also in the majority of patients not requiring reoperation, the echocardiographic evaluations showed good results. Significant mitral valve stenosis occurred in 13.6% and severe valve incompetence in only 6.8%. Most patients had a good left ventricular function with normal myocardial diameters, which highlights the excellent hemodynamic of the native valve.
In conclusion, long-term results for open as well as for closed commissurotomy are excellent. Although commissurotomy represents a more palliative surgical treatment and reoperation may occur, patients who underwent this procedure do benefit both in terms of low valve-related complications and a good quality of life. However, in terms of early and late survival this study did not show any significant differences between the open and closed technique. Nevertheless, the incidence of reoperation as well as of valve-related morbidity and mortality was significantly lower after open commissurotomy. The open technique produced no early failures due to postoperative mitral regurgitation. In addition, the open technique allows the surgeon to remove atrial thrombi, to repair the subvalvular apparatus, to carry out debridement of calcium deposits, and to perform an annuloplasty. Thus, open commissurotomy is a safe surgical intervention with an excellent long-term survival rate and a low incidence of valve-related complications. In well-selected patients with pure mitral stenosis and no leaflet calcification, open commissurotomy still remains a valid surgical option.
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References |
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TopAbstractIntroductionPatients and methodsResultsCommentReferences |
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