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J Thorac Cardiovasc Surg 2007;133:995-1003
© 2007 The American Association for Thoracic Surgery
Surgery for Acquired Cardiovascular Disease |
a Division of Cardiovascular Surgery, Yonsei Cardiovascular Center and Research Institute, Yonsei University College of Medicine, Seoul, Republic of Korea
b Division of Cardiology, Yonsei Cardiovascular Center and Research Institute, Yonsei University College of Medicine, Seoul, Republic of Korea.
Read at the Eighty-sixth Annual Meeting of The American Association for Thoracic Surgery, Philadelphia, Pa, April 29-May 3, 2006.
Received for publication April 29, 2006; revisions received September 14, 2006; accepted for publication October 14, 2006. * Address for reprints: Byung-Chul Chang, MD, Division of Cardiovascular Surgery, Yonsei Cardiovascular Center, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemun-gu, Seoul, South Korea 120-752. (Email: bcchang{at}yumc.yonsei.ac.kr).
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Abstract |
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Methods: From January 1995 through August 2005, 363 patients underwent mitral valvuloplasty with annuloplasty rings. We chose the ring with randomization for mitral valve repair, and the data were collected prospectively. Seven patients who had undergone re-repair or replacement because of failure of initial repair confirmed by means of intraoperative transesophageal echocardiography were excluded in this study, and 356 patients were enrolled (Carpentier ring group, n = 186; Duran ring group, n = 170). Mean age was 49.4 years and 50.3 years for the Carpentier and Duran ring groups, respectively. There were no significant differences in age, sex, body surface area, or cause of mitral regurgitation between the 2 groups.
Results: There were 4 (1.1%) operative mortalities. The patients were followed up for 3 to 126 months (mean, 46.6 months), and total follow-up was 1368.2 patient-years. The left ventricular end-diastolic diameter, left ventricular end-systolic diameter, and left atrial size were significantly decreased in both groups. However, there was no difference in the long-term echocardiographic results between the 2 groups. Overall actuarial survivals at 10 years were 85.9% ± 4.9% in the Carpentier ring group and 75.7% ± 7.2% in the Duran ring group, without a significant difference. Significant mitral regurgitation (grade 
3) recurred in 23 patients (Carpentier ring group, 8; Duran ring group, 15). The 8-year freedom from recurrence of significant mitral regurgitation was 62.6% ± 19.0% in the Carpentier ring group and 55.5% ± 14.1% in the Duran ring group (P = .172). Independent prognostic factors for recurrence of mitral regurgitation in logistic regression analysis were preoperative tricuspid regurgitation of grade 3 or greater and residual mitral regurgitation of grade 2 or greater at the 5th 
7th postoperative days.
Conclusions: Mitral valvuloplasty favors the excellent surgical and long-term results in our prospective randomized study, regardless of the type of annuloplasty ring. There was no difference between the rigid and flexible rings in terms of left ventricular systolic function measured with echocardiography. It seems that timing of the operation before significant tricuspid regurgitation and precise mitral valve repair might prevent late recurrence of mitral regurgitation.
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Introduction |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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Reconstruction of the valve for mitral regurgitation (MR) has been thought to be the treatment of choice, even in patients with mild or no symptoms. Numerous long-term studies have demonstrated excellent results in terms of being free from reoperation and valve-related complications after mitral valve reconstruction. However, there are still controversies in the selection of prosthetic materials for annuloplasty.
Basically, there are 2 types of prostheses: the rigid ring developed by Carpentier and colleagues,1
which restores the mitral annulus to its normal size and shape, and the totally flexible ring developed by Duran and associates,2 which also reduces the annular size but allows for it to continuously change during the cardiac cycle.3
Physiologically, the shape and area of the mitral annulus are changing during the cardiac cycles with ventricular motion.4 Experimental fixation of the mitral annulus with a rigid ring prosthesis impairs left ventricular systolic function.5 Also, the same group demonstrated that a flexible annuloplasty ring results in better left ventricular systolic function than a rigid annuloplasty ring 2 to 3 months after mitral valve reconstruction.6 The same results were also reported by Okada and coworkers3 using echocardiographic techniques 6 months after mitral valve reconstruction. However, there are contrary studies7,8 that report no harmful effects with a rigid ring. Also, there is a possibility of a high incidence of recurrence of MR with a rather round shape of flexible ring in patients with left ventricular dilatation. Thus the shape of the mitral annulus, in addition to reduction of its area after annuloplasty, might play an important role in preventing the recurrence of regurgitation. A prospective clinical study was undertaken in a randomized fashion to understand the roles of annuloplasty rings (the ellipsoidal rigid ring and the rather spherical flexible ring) on long-term results.
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Materials and Methods |
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Of the 356 patients, a Carpentier ring was used in 186 patients, and a Duran ring was used in 170 patients. The mean age of the patients was 49.9 years (range, 17-83 years). There were no differences in sex, age, preoperative New York Heart Association functional class, incidence of atrial fibrillation, or cause of regurgitation (Table 1).
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Surgical Techniques
Transesophageal echocardiography was performed in all patients after the induction of anesthesia to evaluate valvular and ventricular function during surgical intervention. All operations were performed by one surgeon, and surgical techniques remained substantially unchanged during the study period. Cardiopulmonary bypass was performed after achievement of mild systemic hypothermia (30°C-34°C) by using a membrane oxygenator. Myocardial protection was accomplished with a cold blood cardioplegic solution. The size of the Carpentier annuloplasty ring was selected according to the size of the anterior leaflet; the size of the Duran ring was based on the intertrigonal distance. The valve reconstruction was the same in all patients using the French technique developed by Carpentier.9 Mitral annuloplasty rings were implanted with 2-0 Ethibond (Ethicon, United Kingdom) interrupted horizontal mattress sutures.
Another operative technique that has been used recently is neochordae formation with a Gore-Tex suture (W. L. Gore & Associates, Inc, Flagstaff, Ariz); this is decided according to the underlying pathology. After weaning from cardiopulmonary bypass, MR was re-evaluated by using transesophageal echocardiography. MR greater than grade 2 was considered significant, and the valve was re-repaired (n = 2) or replaced (n = 5).
The techniques of mitral valve repair and concomitant operations are shown in Tables 2 and 3.
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The mean follow-up period was 46.6 ± 32.6 months (43.0 ± 31.5 months for the Carpentier ring and 50.6 ± 33.4 months for the Duran ring), and the cumulative follow-up was 1368.2 patient-years (663.7 patient-years for the Carpentier ring and 704.5 patient-years for the Duran ring).
Statistical Analysis
Valve-related complications were defined in accordance with the guidelines established by the American Association for Thoracic Surgery and the Society of Thoracic Surgeons. All data are presented as the mean ± standard deviation. The variables of the 2 groups were compared by using the unpaired t test. In the analysis of serially checked echocardiographic parameters, the Wilcoxon signed–rank test and the repeated-measures analysis of variance test were applied. Estimates of survival and event-free survival for reoperation and the recurrence of significant MR were calculated by using the Kaplan–Meier method and are reported with 95% confidence limits. Patients were censored (ie, withdrawn from the study at the time of reoperation or at the time of death). The SAS software package (SAS 8.0; SAS Institute, Inc, Cary, NC) was used for the statistical power analysis of these results.
Estimates are reported with their standard errors. Comparisons of the curves were established by using the log–rank test for long-term results. To analyze risk factors affecting late mortality, we reviewed preoperative and intraoperative variables (listed in Tables 1 and 2); multivariable Cox proportional hazards regression models were used to calculate hazard ratios (HRs) after adjustments were made for preoperative factors. Model selection was performed with a backward stepwise method. HRs and 95% confidence intervals (95% CIs) were calculated. Results were calculated by using the statistical software package SPSS 12.0 (SPSS, Chicago, Ill).
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Results |
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The transthoracic echocardiogram performed on the seventh postoperative days revealed that 20 (5.6%) patients had greater than grade 2 MR (grade 2, 14 patients; grade 3 or 4, 5 patients). Among them, 1 patient died postoperatively, 2 patients underwent mitral valve replacement later, and the others are under observation.
Changes in Left Ventricular Function
Preoperative and postoperative left ventricular ejection fractions, left ventricular dimensions, and left atrial dimensions are shown in Table 4. All parameters except left atrial dimensions from the immediate postoperative period to the last follow-up at serial echocardiographic examination had changed significantly (P < .001). The ejection fraction was decreased in the immediate postoperative period; in the late follow-up period, it was increased significantly. The left ventricular dimensions were significantly decreased at the time of serial echocardiography. The left atrial dimension was decreased in the immediate postoperative period, but there was no change at late follow-up. There was no significant difference between the 2 rings in the tendency of changes of each parameter (repeated-measures analysis of variance).
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The Kaplan–Meier survival in all patients was 93.3% ± 1.7% at 5 years (Carpentier ring, 95.6% ± 1.7%; Duran ring, 91.4% ± 2.8%) and 77.4% ± 8.0% at 10 years (Carpentier ring, 85.9% ± 4.9%; Duran ring, 75.7% ± 7.2%; Figure 1). There were no statistical differences in the survival rates between the Carpentier ring group and the Duran ring group (P = .74).
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Infective Endocarditis
Three patients had infective endocarditis, and 1 patient died. Two patients were treated with antibiotics alone. Freedom from infective endocarditis at 10 years was 98.6% ± 0.9% for all patients, 98.7% ± 0.9% for patients in the Carpentier ring group, and 98.6% ± 1.4% for patients in the Duran ring group (P = .56).
Reoperation
Reoperation was required in 8 patients. The causes of reoperation were progression of MR in 5 patients (Carpentier ring, 1; Duran ring, 4), hemolysis in 2 patients with a Duran ring, and endocarditis in 1 patient with a Carpentier ring. The mitral valves were replaced in all 6 patients who had undergone valve repair with a Duran ring. The mitral valves were re-repaired in 2 patients with a Carpentier ring (1 with a chordae rupture and 1 with endocarditis).
Kaplan–Meier analysis for freedom from reoperation in all patients was 99.3% ± 1.7% at 5 years (Carpentier ring, 99.5% ± 0.5%; Duran ring, 95.7% ± 2.3%) and 77.4% ± 8.0% at 10 years (Carpentier ring, 95.5% ± 3.9%; Duran ring, 86.1% ± 7.9%; Figure 3). There were no statistical differences in survival rates between the Carpentier ring group and the Duran ring group (P = .174).
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The Cox proportional hazard model identified MR equal to or greater than grade 2 at the early postoperative period as a risk factor for reoperation (Table 5).
Recurrence of Significant MR
Recurrence of significant MR equal to or greater than grade 3 during the follow-up period occurred in 23 patients (Carpentier ring, 8; Duran ring, 15). Among them, 5 patients required reoperation.
Freedom from significant MR was 92.7% ± 2.2% at 4 years (Carpentier ring, 95.0% ± 2.3%; Duran ring, 90.8% ± 3.7%) and 59.1% ± 11.5% at 8 years (Carpentier ring, 62.6% ± 19.0%; Duran ring, 55.5% ± 14.1%; Figure 4). There were no statistical differences in the recurrence of significant MR between the Carpentier ring group and the Duran ring group (P = .172). The statistical power (ß) of survival analysis in terms of the recurrence of MR was performed to determine whether there was enough power in this model, and it was .751.
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1 vs residual MR 2) was analyzed and found to be 97.6% ± 1.7% in the group with residual MR of grade 1 or less and 50.0% ± 25.0% in the group with residual MR of grade 2 or greater at 4 years and 55.4% ± 23.1% in the group with residual MR of grade 1 or less and 25.0% ± 21.7% in the group with residual MR of grade 2 or greater at 8 years (P < .01).
The Cox regression hazard model identified preoperative tricuspid regurgitation of grade 3 or greater and MR of grade 2 or greater in the immediate postoperative period as risk factors for the recurrence of significant MR (Table 5). We reanalyzed the late failure of MR repair, excluding the early postoperative residual MR (grade 2) because residual MR so strongly related to late MR. The preoperative and intraoperative independent predictors for the recurrence of significant MR included dilated cardiomyopathy (HR, 24.5; 95% CI, 5.7104.5), chordae shortening technique (HR, 7.5; 95% CI, 2.027.9), new chordae formation technique (HR, 5.0; 95% CI, 1.418.1), male sex (HR, 2.7; 95% CI, 1.07.4), and age by increment of 1 year (HR, 1.05; 95% CI, 1.011.09).
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Discussion |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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introduced the concept of annuloplasty in 1957; subsequent suture annuloplasty techniques were developed by Reed and coworkers11 and Kay and Egerton.12 An improved approach that began to address the more complex leaflet pathology was pioneered by Carpentier and colleagues.13 As Carpentier’s results were duplicated, studies began to demonstrate numerous advantages of valve repair over valve replacement. These advantages included improved maintenance of left ventricular function, lower risk of thromboembolism and anticoagulant-related complications, reduced risk of endocarditis, and increased freedom from all valve-related complications. Subsequently, the long-term durability of valve repair became firmly established, and the various advantages of repair over replacement led to an acceptance of valve repair as the preferred treatment of mitral insufficiency.14 This study was designed to compare the long-term results between rigid and flexible rings. Freedom from reoperation and recurrence of MR were somewhat lower in the Duran ring group, but this difference did not reach statistical significance. Among 8 patients who required reoperation, the cause of recurrence of MR in 2 patients was the elongation of the anterior–posterior diameter of the mitral annulus because of the morphologic deformation of the Duran ring, which resulted in the inability to achieve annular fixation; however, it is unclear why the recurrence and reoperation rate is higher in the Duran ring group. More long-term data might be required to make a conclusion on the longevity of different annuloplasty ring types.
Although flexible annuloplasty devices preserve the normal annular motion and orifice area during the cardiac cycle, this benefit might be offset by their decreased ability to geometrically remodel the annulus, which could have a negative effect on late repair durability. David and associates6 showed that patients with flexible ring annuloplasty have better left ventricular systolic function 2 to 3 months postoperatively, but this difference disappears after 1 year. Meanwhile, van Rijk–Zwikker and coworkers8 demonstrated that there were minimal differences of mural leaflet motion and diastolic filling of the basal part of the left ventricle between the rigid and flexible rings in an animal study. These kinds of data were also identified by the Stanford group.7 They demonstrated no significant differences between rigid and flexible rings in terms of left ventricular systolic performance and energetics 1 and 6 weeks after the operation. According to our late follow-up echocardiographic data, mitral valve repair with an annuloplasty ring improved the left ventricular ejection fraction and reduced left ventricular dimension, but there were no statistical differences between the degrees of change of these parameters between the 2 groups.
Recently, minimally invasive surgery for functional MR after myocardial infarction or idiopathic dilated cardiomyopathy focused on mitral annular shape.15 The tethering effect of the posterior mitral leaflet with enlargement of the left ventricular cavity in ischemic or idiopathic dilated cardiomyopathy results in MR. The fundamental surgical concept of dilated cardiomyopathy was to reduce the mitral annulus,16,17 especially the anterior–posterior diameter of the mitral annulus, with coaptation of the anterior and posterior leaflet. In this point of view, mitral annulus shape, as well as size, is thought to be very important to long-term outcome. In this series we could not find any significant differences in Kaplan–Meier survival, freedom from reoperation, and recurrence of significant MR. However, there was less incidence of recurrence of significant MR in the Carpentier group without significance (P = .172). Therefore it seemed that annuloplasty with a rigid ring might prevent the recurrence of MR with prevention of elongation of the anterior-posterior diameter of the mitral valve.
Even though the causes of MR were heterogeneous, it seems that the causes of MR have little influence on the results. The most common cause of MR was degenerative disease. Mitral valve repair is most applicable to patients with degenerative mitral valve disease, with successful valvuloplasty possible in 95% of such patients.18 Furthermore, mitral valve repair in these patients has its greatest durability. Deloche and colleagues19 found that the 15-year freedom from reoperation after mitral valve repair was 93% in patients with degenerative disease; this is similar to our results. The second most common cause of MR was rheumatic disease. The appropriateness of valve repair for patients with rheumatic mitral valve disease (even when repair appears to be technically feasible) is controversial.20 However, Yau and associates21 reported that 10-year freedom from reoperation was 87%, and rheumatic mitral valves should be repaired when technically feasible, accepting a risk of reoperation to maximize survival and reduce morbidity. Even though only a few rheumatic patients (11.2%) were included in this study, there were no late reoperations in patients with rheumatic disease. Most patients with rheumatic mitral stenosis underwent mitral valve replacement because of advanced stage with severe calcification in our hospital. However, mitral valve repair has been recommended in cases of significant MR, even with severe fibrosis. We think that precise preoperative evaluation of the valvular apparatus and careful decision making considering the feasibility of mitral valve repair in these patients led to such a good result.
The Cox regression hazard model revealed that the most potent risk factor for recurrence of significant MR after mitral repair was residual MR observed at the fifth to seventh postoperative days. Flameng and coworkers22 reported that when recurrence of any degree of regurgitation, be it minor, moderate, or severe, is considered, only about 50% of patients remain free from more than trivial mitral incompetence at 7 years after repair. These findings strongly suggest a progression of the disease process with time that results in an increasing degree of valve incompetence.
Even though this study was designed as a prospective and randomized study, the number of patients in both groups was somewhat different. The reason is that 7 patients included initially in this study were excluded later because they underwent reoperation because of residual MR demonstrated by means of intraoperative transesophageal echocardiography. However, during the analysis, the patients were excluded because of removal of bias of long-term results. Including the 7 patients who were excluded from this study, freedom from significant MR was 57.9% ± 11.2% at 8 years (Carpentier ring, 61.8% ± 18.8%; Duran ring, 53.7% ± 13.7%). Also, there were no statistical differences in the recurrence of significant MR between the Carpentier ring group and the Duran ring group (P = .072). However, there was a trend toward difference with time between the groups. There might be a possibility of a significant difference in recurrence of significant MR between 2 groups with longer follow-up.
In patients with rheumatic MR, the long-term results were better than others. There might be a selection bias for mitral valve repair. Most patients with rheumatic MR combined with stenosis underwent mitral valve replacement. Therefore the long-term results might be excellent. There was no significant difference between the 2 types of prosthetic rings in early and long-term results. In this study the number of patients with cardiomyopathy was too small for statistical analysis, and further study should be necessary.
In conclusion, in this prospective and randomized study, we compared the effects of 2 different annuloplasty rings on early and long-term clinical results in patients with MR. Mitral valve annuloplasty with both rings showed good long-term clinical results. There were no statistical clinical differences between the Carpentier ring and the Duran ring, and follow-up echocardiography demonstrated that both early and late postoperative left ventricular dimensions were significantly reduced and that left ventricular function was significantly improved in both groups. More long-term data might be required to determine the superiority of either of the rings. Meticulous operative skills and intraoperative transesophageal echocardiographic evaluation are mandatory to prevent the late recurrence of MR.
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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