Ann Thorac Surg 2005;80:820-824
© 2005 The Society of Thoracic Surgeons
Original article: Cardiovascular
Risk Factors of Posterior Pericardial Annuloplasty for Isolated Posterior Leaflet Prolapse
Seiji Matsukuma, MD
*
,
Kiyoyuki Eishi, MD,
Shiro Yamachika, MD,
Hiroichiro Yamaguchi, MD,
Tsuneo Ariyoshi, MD,
Youichi Hisata, MD,
Kazuyoshi Tanigawa, MD,
Kenta Izumi, MD,
Hideaki Takai, MD
Department of Cardiovascular Surgery, Nagasaki University School of Medicine, Nagasaki, Japan
Accepted for publication March 21, 2005.
* Address reprint requests to Dr Matsukuma, Nagasaki University School of Medicine, Department of Cardiovascular Surgery, 1-7-1 Sakamoto, Nagasaki City, Nagasaki 852-8501, Japan (Email: seiji731{at}net.nagasaki-u.ac.jp).
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Abstract
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BACKGROUND: Posterior autologous pericardial annuloplasty is an option in mitral valve repair. However, the durability of posterior pericardial annuloplasty remains controversial.
METHODS: From June 1999 to July 2004, 49 patients (18 male and 31 female; mean age, 64 ± 12 years) with isolated posterior leaflet prolapse received posterior autologous pericardial annuloplasty. Transthoracic echocardiographic examination before the operation, at the time of discharge, and then annually was performed and analyzed.
RESULTS: There was no incidence of in-hospital or late death. Only 1 patient (2.1%) required reoperation. In terms of recurrent mitral regurgitation, 31 patients (64.6%) exhibited grade 0 mitral regurgitation, 7 patients (14.6%) exhibited grade 1, and 9 patients (18.8%) exhibited grade 2, whereas only 1 patient (2.0%) exhibited more than grade 3. In terms of predicting postoperative recurrence of significant mitral regurgitation (
grade 2), multivariate Cox analysis demonstrated that marked left atrial dilatation and high fractional shortening were independent risk factors. In 8 of 10 patients significant mitral regurgitation recurred after discharge. In terms of left atrial dimension, no significant reduction was observed in the postdischarge recurrent group, and there was a significant difference of left atrial dimension between the postdischarge recurrent group and the nonrecurrent group at the time of discharge.
CONCLUSIONS: The merits of mitral valve repair using posterior autologous pericardial annuloplasty are attractive. However, its use should be limited in selected patients with isolated posterior leaflet disease, nonenlarged atria, and non-high fractional shortening to maintain the durability of the mitral valve repair.
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Introduction
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Mitral valve (MV) repair is superior to replacement in improving outcome [1, 2], and the most durable repairs are obtained in patients with isolated posterior leaflet prolapse [3]. Mitral valve annuloplasty is generally performed to assure the durability of the repair [3, 4]. Posterior autologous pericardial annuloplasty (PPA) has been described as an alternative option to MV repair [[3–5]. The advantages of PPA are that it is flexible, maintains the physiologic movements of the mitral annulus, and negates the need for foreign material implantation. However, the durability of PPA is controversial 3, 6–8]. The durability of PPA should not be assessed in a study that includes anterior leaflet prolapse repair because the repair of anterior leaflet prolapse is a risk factor itself [3, 9, 10]. Therefore, the purpose of this retrospective study was to assess midterm follow-up results of MV repair using PPA for isolated posterior leaflet prolapse, and to identify possible predictive factors of the recurrence of mitral regurgitation (MR) on the basis of preoperative factors.
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Patients and Methods
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From June 1999 to July 2004, of the 127 patients who underwent MV repair because of MR, 49 patients with isolated posterior leaflet prolapse received PPA at a single institution. The study population consisted of 18 male (37%) and 31 female (63%) patients with a mean age of 64 ± 12 years. The cause of MR was degenerative disease in 42 patients (86%), acute or healed endocarditis in 6 patients (12%), and rheumatic disease in 1 patient (2%). Preoperative patient characteristics are listed in Table 1.
Surgical Technique
The same surgeon (K. E.) operated on all patients. The operations were performed through a conventional median sternotomy. Moderate hypothermic cardiopulmonary bypass was established using bicaval and ascending aortic cannulation. Myocardial protection was achieved with antegrade cold crystalloid cardioplegia. After aortic cross-clamping, the mitral valve was exposed through a right-sided left atriotomy under cardioplegic arrest. Posterior quadrangular resection was performed in 43 patients (88%), chordae transposition in 1 patient (2%), chordae replacement with Gore-Tex (W.L. Gore & Assoc, Flagstaff, AZ) suture in 1 patient (2%), paracommissural edge-to-edge repair in 3 patients (6%), and paracommissural Kay in 1 patient (2%). In 4 patients (8%), autologous pericardial patches were added to reinforce the repair region in cases of thin mitral leaflet. Posterior pericardial annuloplasty was performed with twisted autologous pericardium in all patients. A rectangular strip of the pericardium (approximately 3 x 6 cm2) was harvested and cleared of adherent adipose tissue. This strip was folded with the serosal surface outside and then twisted. The length of the pericardial ring was determined according to the anterior leaflet free-edge length measured by Carpentier-Edwards size obturator, which was selected on the basis of the anterior leaflet surface extension. The twisted pericardial ring was fixed with mattress sutures along the posterior annulus, just beyond the anatomic commissures. The associated procedures were carried out concomitant with MV repair, including coronary artery revascularization in 2 patients (4%), pulmonary veins cryoisolation of atrial fibrillation in 5 patients (10%), aortic valve replacement in 2 patients (4%), and ventricular septal defect closure in 1 patient (2%).
Echocardiographic Assessment
All patients underwent transthoracic echocardiographic examination before the operation, at the time of discharge from the hospital, and then annually. Chamber dimensions (left ventricular end-diastolic dimension, left ventricular end-systolic dimension, left atrial dimension [LAD], and left ventricular fractional shortening [FS]) were obtained from M-mode findings. The grade of MR was evaluated by means of the maximum regurgitant jet area. The range from 0 to 2 cm2 was considered as none or trivial (grade 0), between 2 and 4 cm2 was considered as trivial to mild (grade 1), between 4 and 8 cm2 was considered as mild to moderate (grade 2), between 8 and 12 cm2 was considered as moderate to severe (grade 3), and greater than 12 cm2 was considered as severe (grade 4). Intraoperative transesophageal echocardiography was performed in all patients. Revision of the repair was performed when a regurgitation area greater than 2 cm2 was detected.
Statistical Analysis
Values are presented as mean ± standard deviation. Differences in the means of continuous measurements were assessed by paired Student’s t test. Categorical variables were presented by their number and summarized as a percentage, and were compared by means of nonparametric Mann-Whitney U test. The time course of left ventricular end-diastolic dimension, left ventricular end-systolic dimension, FS, and LAD levels were analyzed between groups by two-way analysis of variance for repeated measurements. When a significant overall effect was detected, Tukey’s honest significant difference test was performed to compare single mean values. Univariate and multivariate Cox proportional hazards models were used to evaluate predictors of recurrent MR of grade 2 or higher. For follow-up of the recurrence of MR, Kaplan-Meier analysis was used. For all analyses, p values less than 0.05 were considered statistically significant. All statistical analyses were performed using the SPSS 11.0 software (SPSS, Inc, Chicago, IL).
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Results
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The mean durations of aortic cross-clamp and extracorporeal circulation were 63 ± 20 minutes and 108 ± 40 minutes, respectively. There was no incidence of in-hospital or late death. Follow-up was performed for 97.9% of the patients, and the mean follow-up was 23.9 ± 16.8 months (range, 1 to 56 months). Only 1 patient (2.1%) required reoperation for severe MR caused by suture dehiscence of the leaflet plication before discharge from the hospital. Postoperative complications consisted of cerebral infarction in 1 patient (2.1%), and systolic anterior motion in 2 patients with tachycardia and hypovolemia. However, systolic anterior motion was well controlled and disappeared by administration of a ß-blocker in both patients. Any other postoperative complications (endocarditis, hemolysis, ring dehiscence, and so forth) did not occur during the follow-up.
In terms of recurrent MR in 48 patients (excluding 1 reoperated patient), at the time of follow-up after discharge 31 patients (64.6%) exhibited grade 0 MR, 7 patients (14.6%) exhibited grade 1 MR, and 9 patients (18.8%) exhibited grade 2 MR, whereas only 1 patient (2.0%) exhibited grade 3 or greater MR with transthoracic echocardiography. The rate of freedom from reoperation and recurrent MR of grade 3 or greater was 95.9%, and the rate of freedom from MR of grade 2 or greater was 77.5% (Fig 1). In terms of preoperative transthoracic echocardiographic factors, preoperative LAD in the 10 recurrent patients (45.9 ± 6.5 mm) was significantly larger than that of the 38 nonrecurrent patients (40.9 ± 5.5 mm; p = 0.015). In terms of predicting the postoperative recurrence of significant MR (grade 2), univariate analysis showed that preoperative New York Heart Association class, marked left atrial dilatation (>50 mm), and high FS (>50%) were potential indicators of postoperative recurrence of significant MR.
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Fig 1. The Kaplan-Meier curve: Freedom from recurrence of mitral regurgitation (MR) of grade 2 or greater.
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Multivariate Cox analysis showed that marked left atrial dilatation and high FS were independent risk factors for postoperative recurrence of significant MR (Table 2). As a whole, follow-up transthoracic echocardiographic assessment showed significant reduction in the left ventricular end-diastolic dimension (mean difference, 9.16 mm; 95% confidence interval, 7.57 to 10.75 mm; p < 0.001), left ventricular end-systolic dimension (mean difference, 3.29 mm; 95% confidence interval, 1.91 to 4.67 mm; p < 0.001), and LAD (mean difference, 3.49 mm; 95% confidence interval, 1.70 to 5.28 mm; p < 0.001). A decrease in the FS was also documented along with the decrease of left ventricular end-diastolic dimension, although FS was not below normal range throughout the study.
At the time of discharge, 46 patients (93.9%) exhibited grade 0 or 1 residual MR, whereas 2 patients (4.1%) exhibited grade 2 residual MR. Both of these patients exhibited marked left atrial dilatation preoperatively. During the follow-up period, in 46 patients who exhibited grade 0 or 1 residual MR at discharge, a subpopulation of 8 patients (group B) was identified who exhibited recurrence of significant MR (grade 2) and could be compared with the remaining 38 patients who did not (group A). Two patients who exhibited significant recurrent MR before discharge were excluded to ignore the influence of significant MR to the echocardiographic variables, such as LAD, at the time of discharge. There was no significant difference of preoperative variables in both groups.
A significant reduction of FS was observed in both groups at discharge and tended to increase in both groups at follow-up but returned to the near preoperative values in group A (Fig 2). There was a significant reduction of left ventricular end-diastolic dimension both at the time of discharge and at the follow-up in both groups, compared with preoperative values (Fig 3). No significant reductions of left ventricular end-systolic dimension were observed in either of the two groups at discharge, but left ventricular end-systolic dimension tended to decrease significantly in group A at the time of follow-up (Fig 4). However, in terms of LAD, although all residual MR was grade 1 or lower in both groups at the time of discharge, a significant reduction was observed in group A, but not in group B (Fig 5). There was a significant difference of LAD between these two groups at the time of discharge (p = 0.007; Fig 5).
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Fig 2. Fractional shortening (FS) values of 46 patients (2 patients who recurred significant mitral regurgitation before discharge were excluded) at preoperation (preop), discharge, and follow-up. Group A (n = 38): residual grade 0, 1 mitral regurgitation; group B (n = 8): residual grade 2, 3 mitral regurgitation. *p < 0.05 versus preoperative values; p < 0.05 versus preceding values. (SD = standard deviation.)
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Fig 3. Left ventricular end-diastolic dimension (LVEDD) values of 46 patients (2 patients who recurred significant mitral regurgitation before discharge were excluded) at preoperation (preop), discharge, and follow-up. Group A (n = 38): residual grade 0, 1 mitral regurgitation; group B (n = 8): residual grade 2, 3 mitral regurgitation. *p < 0.05 versus preoperative values. (SD = standard deviation.)
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Fig 4. Left ventricular end-systolic dimension (LVESD) values of 46 patients (2 patients who recurred significant mitral regurgitation before discharge were excluded) at preoperation (preop), discharge, and follow-up. Group A (n = 38): residual grade 0, 1 mitral regurgitation; group B (n = 8): residual grade 2, 3 mitral regurgitation. *p < 0.05 versus preoperative values; p < 0.05 versus preceding values. (SD = standard deviation.)
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Fig 5. Left atrial dimension (LAD) values of 46 patients (2 patients who recurred significant mitral regurgitation before discharge were excluded) at preoperation (preop), discharge, and follow-up. Group A (n = 38): residual grade 0, 1 mitral regurgitation; group B (n = 8): residual grade 2, 3 mitral regurgitation. *p < 0.05 versus preoperative values; p < 0.05 versus preceding values;  p < 0.05 versus group B. (SD = standard deviation.)
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Comment
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Mitral valve repair is recognized as a superior method to MV replacement [1, 2], and the concept that the addition of an annuloplasty enhances the durability of MV repair is gaining ground [3, 4]. The first ring annuloplasty was introduced by Carpentier in 1969 [11]. Several annuloplasty devices were reported thereafter, and Cosgrove and coworkers [12] eventually introduced the flexible semicircular ring because pathologic dilatation of the mitral annulus occurred along the attachment of the posterior leaflet whereas the distance between the fibrous trigones anteriorly remained stable [12, 13,]. Posterior autologous pericardial annuloplasty, introduced by Salati and coworkers [5] in 1991, is an alternative approach, based on the pathologic annular dilatation concept. Many advantages of PPA, such as preservation of the physiologic movement of the annulus and left ventricular performance, avoidance of foreign material implantation, reduction of morbidity (endocarditis, thromboembolism, hemolysis), and cost-effectiveness, are anticipated. However, the durability of PPA is now controversial [3, 6–8].
In anterior leaflet prolapse cases, some cases with flaccid deformity of the anterior annulus and dilatation of anteroposterior diameter have been observed [14]. Therefore, we considered that remodeling of the annulus, including reduction of anteroposterior diameter and stabilization of the anterior annulus using total annular remodeling rings, such as the Carpentier physio-ring [15], is indispensable for durable repair in anterior leaflet prolapse cases. Regarding the repair durability, in this study the rate of freedom from recurrence of significant MR was 77.5%. It was less than that of the Carpentier physio-ring reported by Raffoul and associates [16], at medium-term follow-up (98.7%, 23 ± 13 months). Considering these results, PPA could not be regarded as an acceptable option for all patients with isolated posterior leaflet prolapse.
In this study, preoperative factors, namely marked left atrial dilatation (>50 mm) and high FS (>50%), were directly related to the recurrence of significant MR (grade 2). We assessed the transition of echocardiographic factors in 46 patients. We excluded 2 patients with significant recurrent MR before discharge to ignore the influence of significant recurrent MR on these factors at the time of discharge. At the time of discharge from the hospital, significant reduction of LAD compared with preoperative diameter was not recognized in the group with recurrence of significant MR at the follow-up, in contrast to the nonrecurrent group. In addition, there was a significant difference of LAD between the two groups at the time of discharge. In general, during the acute phase of severe MR, left atrial compliance is almost normal. The left atrium is not enlarged, but the mean left atrial pressure is elevated. As the MR becomes chronic, left atrial compliance is increased, left atrium is markedly enlarged, the atrial wall becomes fibrotic, but left atrial pressure gradually decreases to nearly normal. On echocardiographic assessment, FS is, in appearance, greater than normal in patients with severe MR and dilated left atrium who are not in left ventricular failure, because severe MR increases left ventricular preload and end-diastolic volume, and represents a low impedance systolic leak into the left atrium that reduces left ventricular afterload and end-systolic volume [17, 18]. In other words, high FS in the recurrent group reflects this condition, and the recurrent group in the present study can be recognized as a chronically compensated group with irreversibly dilated left atrium.
Several studies have indicated that left atrial dilatation is indirectly associated with failure of MV repair [7, 19], but that left atrial dilatation can influence MR. As the left atrium dilates, the left atrial posterior wall tends to hang over the atrioventricular sulcus and the posterior mitral leaflet is pulled cephalad because the posterior leaflet is continuous with the left atrial endocardium [20]. As a result, coaptation of the mitral leaflets is decreased. Furthermore, the annulus of the myxomatous degenerated valve, particularly one that was chronic, may be deformed to such a degree [4, 21, 22] that reshaping of the annulus is important. Judging from our study, PPA produces enough coaptation in case of dilatation of the posterior annulus alone, but in cases of complete annular dilatation, PPA might be too flexible to decrease the anteroposterior diameter of the mitral annulus for increasing leaflet coaptation and to control remodeling of the deformed annulus. We considered that these were the causes of early recurrence of MR in the chronic group. In addition, Flameng and coworkers [21] reported that repaired valves remained degenerative and that their durability was limited. In their study, a constant rate of recurrence of MR was observed in the degenerative valve disease group [21]. We believe that this might be one of the reasons for our late recurrence of MR.
This is a single institution study and is, therefore, limited to a small number of patients. This study design was retrospective and did not assess the superiority of PPA to other devices. Almost all of this study population joined during the compensatory period. Thus, this study could not assess the effectiveness and durability of PPA in a chronically decompensated MR group.
In conclusion, MV repair using PPA exhibited fewer ring-related complications. However, even if left ventricular performance is preserved, marked preoperative left atrial dilatation and irreversible postoperative left atrial dilatation can indicate the possibility of postoperative recurrence of significant MR. The merits of MV repair using PPA are attractive, but should be limited in selected patients with isolated posterior leaflet disease, nonenlarged atria and non-high FS to maintain the durability of MV repair.
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Acknowledgments
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We are very grateful to Mizuyo Okabe, Mikiko Noguchi, and Jun Sekiyama for their invaluable support.
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Abstract
Introduction
