Introduction: A prospective randomized trial of surgical treatment for functional mitral regurgitation (FMR) has reported that there was no significant difference in 2-year survival between mitral annuloplasty and mitral valve replacement. However, mitral valve repair with the manipulation of mitral subvalvular apparatus has not been sufficiently investigated. This study investigated the surgical outcome in our institution.
Hypothesis: Mitral valve repair with intervention to subvalvular apparatus has a potential to improve the outcome for FMR.
Methods: Among 494 patients undergoing mitral valve surgery between 2005 and 2016 in our hospital, 66 patients who underwent mitral valve repair for FMR were studied. The mean age of the study patients was 69 years, mean left ventricular diastolic dimension 65mm, mean left ventricular ejection fraction 37%, and 48 cases were ischemic MR. Annuloplasty rings were used for all cases. Interventions to mitral subvalvular apparatus were as follows; secondary chordae cutting in 22 cases, papillary muscle relocation in the direction of the anterior annulus (A-PMR) in 16 cases, papillary muscle relocation in the direction of the posterior annulus in 10 cases and papillary muscle approximation in 4 cases. Long-term survival and freedom from recurrent MR of these 66 patients were investigated.
Results: The overall 2-year and 5-year survivals were 82% and 74% respectively. A Cox proportional hazards analysis found that decreased anterior leaflet diastolic angle (ALAd) was a risk factor for the survival [hazard ratio .886, P=.029]. The cut-off value of ALAd was 51 degrees. A-PMR was identified as a procedure to increase postoperative ALAd [mean preoperative/postoperative angle: 61/72 degrees, P=.009]. The freedom from recurrent MR was 85.8% at 5 years. The freedom from recurrent MR in the cases of interventions to the subvalvular apparatus (n=33) was 96% at 5 years, which was better than the 73% in the cases of mitral annuloplasty without the subvalvular intervention [P=.035].
Conclusions: Decreased preoperative ALAd was a risk factor for survival after mitral valve repair for FMR, but the improvement could be expected by A-PMR. Recurrent MR was decreased by mitral valve repair with manipulation of subvalvular apparatus.