Objectives

The optimal treatment of functional mitral regurgitation (FMR) with restricted leaflet motion during systole (type IIIb MR) due to left ventricular dysfunction is still controversial. Apart from guideline-directed medical therapy and cardiac resynchronization therapy, which only partially improve the symptoms of heart-failure, the correction of mitral regurgitation (MR) may additionally improve the prognosis of type IIIb MR patients. The major drawback of surgical mitral valve repair using an isolated mitral annuloplasty in type IIIb MR patients is the reoccurrence of MR, which results in progressive heart-failure and repeated hospitalizations. Therefore, subannular repair techniques in addition to undersized mitral ring annuloplasty have been developed to address high MR reoccurrence-rates after MV repair in type IIIb MR. We compared the results of mitral annuloplasty with simultaneous standardized subannular repair vs. isolated mitral annuloplasty.

Methods

A consecutive series of 108 type IIIb FMR patients which met the inclusion criteria of (1) left ventricular ejection fraction < 40%, (2) LVEDD > 55 mm, (3) tenting height > 10 mm, and (4) severe echocardiographic signs of bileaflet tethering underwent an mitral annuloplasty + subannular repair (Group A; n=60) vs. isolated mitral annuloplasty (Group B; n=48). Primary endpoint of this prospective, parallel cohorts’ study was the reoccurence of MR > 2, one year postoperatively. Secondary endpoints were survival and clinical outcomes, with special regard to the minimally invasively treated subgroups.

Results

Duration of surgery, cardiopulmonary bypass time and aortic cross-clamp time were comparable between both study groups, whereas 55% of patients in Group A were treated minimally invasively via a right anterolateral minithoracotomy. Procedural outcomes as well as postoperative echocardiographic parameters of residual MR were similar and independent of access. Postoperative residual tenting height was significantly decreased in Group A (5.9 ± 1.4 mm) vs. Group B (9.9 ± 2.2 mm) (p< 0.001). At 12-months follow up there was a further decrease in echocardiographic parameters of residual MV tenting in Group A, whereas they remained unchanged in Group B. Furthermore, at 12-months follow up MR > 2 reoccurred in 1.7% [1/60] of patients in Group A vs. 12.5% [6/48] of patients in Group B (p< 0.05). The overall mortality during follow-up was 12.5% [6/48] in Group B, vs. 1.7% [1/60] in Group A (p< 0.05).

Conclusion

Surgical mitral valve repair in type III FMR patients with reduced left ventricular function is still justified due to excellent in-hospital and 1-year follow-up outcomes. Standardized realignment of both papillary muscles in addition to mitral annuloplasty is feasible and reproducible via a minimally invasive approach, resulting in excellent periprocedural outcomes. Furthermore, it has a clear potential to significantly decrease MR reoccurrence and improve 1-year outcomes as compared to isolated mitral annuloplasty. Apart from transcatheter mitral-valve repair, enhanced surgical mitral valve repair, which can be safely performed in a minimally invasive mitral valve surgery setting, still represents a valid therapeutic option for heart-failure patients with decreased left ventricular function suffering from type IIIb MR.