Standardized Subannular Repair for Treatment of Secondary Mitral Regurgitation: Initial Results from the Reform-MR Registry

Objectives: Optimal surgical treatment of secondary mitral regurgitation (MR) due to cardiomyopathy is still controversial. Subannular repair using papillary muscle repositioning as an adjunct to annuloplasty has been developed to improve the stability of MV repair in type IIIb MR and demonstrated very promising results in monocentric studies. Herewith we report initial results from multicenter German REFORM-MR registry that was designed to evaluate standardized subannular repair in a multicenter setting.

Methods: Consecutive type IIIb MR patients were included in a prospective single-arm multicenter REFORM-MR registry at six German centers between July 2018 and August 2020. All patients met the following inclusion criteria (1) LVEF < 50%, (2) LVEDD ≥ 55 mm, (3) tenting PML or AML ≥10 mm and underwent standardized subannular repair using bilateral papillary muscle repositioning plus standard annuloplasty. Combination surgery (e.g., simultaneous CABG) was allowed, except for aortic valve surgery. Imaging data were analyzed independently by Echo/MRI Core Labs. Primary endpoint was the freedom of MR > 2 at 2 years postoperatively, secondary endpoints were survival, freedom of MACCE and mitral valve reinterventions. Herewith, we report in-hospital results.

Result: A total of 71 patients (mean age: 64.8 ± 9.6 years, 65% male) with type IIIb MR were included. Mean preoperative LVEF was 35.6 ± 9.5%, mean LVEDD: 61.8 ± 8.7 mm. Mean log. EuroSCORE was 10.1 ± 8.9%, STS score for mortality: 3.2 ± 3.6%. Urgent surgery was required in 25 (36%) patients, 22 (31%) patients underwent minimally-invasive surgery. Bilateral papillary muscle repositioning was feasible in all patients, and mean annuloplasty ring size was 29.8 ± 1.8 mm. Concomitant surgery was required in 61 (86%) patients, most of them underwent simultaneous CABG (61%). In-hospital mortality was 1.4%. Residual MR at discharge was none/mild in 66 (93%) patients, 5 (7%) patients had moderate MR. Mitral valve tenting parameters were significantly reduced after subannular repair (i.e., tenting height: 7.2 ± 2.7 mm vs. 11.4 ± 3.0 mm, p < 0.01 and tenting area: 158.4 ± 59.9 mm² vs. 351.4 ± 100.2 mm², p < 0.01).

Conclusion: Standardized subannular repair using papillary muscle repositioning can be safely and reproducibly performed in a multicenter setting. Our results demonstrate very satisfactory in-hospital outcome with low prevalence of residual MR. Longer follow-up of the study cohort is required to confirm these promising results.

Publication History

Article published online:
19 February 2021