Comparison of flexible and rigid annuloplasty rings in isolated mitral regurgitation

Abstract

Objectives: The aim of this study was to examine the early and midterm results of various annuloplasty rings in terms of residual mitral regurgitation (MR) in patients undergoing mitral valve repair. Patients and methods: In the retrospective study, 298 patients (157 males, 141 females; mean age: 58.8±14.3 years; range, 16 to 82 years) underwent repair between September 2009 and April 2012. Two hundred eleven were assigned to the flexible ring group (Group 1), whereas 87 were included in the rigid ring group (Group 2). Mitral pathologies were divided into three subgroups: ischemic, degenerative, and rheumatic. Results: The causes of mitral pathology were ischemic in 36.2%, degenerative in 54.4%, and rheumatic in 9.4%. Concomitant surgical procedures were present in 87%. The follow-up period ranged from 2 days to 33 months, with a mean of 15.8±7.5 months. The 30-day mortality rate was 9.2% and 10.4% in Groups 1 and 2, respectively. There was a high rate of successful repair in the rigid group with 88.5% and acceptable rate of repair in the flexible group with 72%. Mitral regurgitation was significantly reduced after intervention regardless of the ring type (p<0.01). Significant improvement in NYHA class was observed in both groups. Recurrent regurgitation was detected in 27.9% of patients in Group 1 and 11.5% in Group 2. Recurrence occurred within three to nine months following the surgery. Reoperation rates for residual MR were 3.3% (n=7) vs. 1.1% (n=1) in Groups 1 and 2, respectively (p=0.293). Conclusion: Saddle-shaped rings provide a mechanical benefit through a low and uniform force distribution and improve repair durability compared to flat rings. As a result, the rigid ring had a significant advantage, particularly in degenerative and rheumatic subgroups, but there was a loss of superiority in late ischemic MR due to left ventricle remodeling.