Subannular repair for functional mitral regurgitation type IIIb in patients with ischaemic versus dilated cardiomyopathy.

Objectives: Functional mitral regurgitation (FMR) is a sequel of left ventricular (LV) remodelling in heart failure patients. Relocation of both papillary muscles aims to specifically address mitral leaflet tethering to improve long-term durability of modern FMR repair. Nevertheless, the prognostic impact of the underlying cardiomyopathy on the outcome after FMR repair is unknown.

Methods: We analysed 84 consecutive heart failure patients with severe FMR, LV ejection fraction <40%, LV end-diastolic diameter ≥55 mm and tenting height >10 mm, who underwent ring annuloplasty and simultaneous bilateral papillary muscles relocation between June 2016 and March 2019. One-year outcome of 54 patients with ischaemic cardiomyopathy ('ICM group') was prospectively compared to the remaining 30 patients with dilated cardiomyopathy ('DCM group').

Results: One-year survival was similar in both groups (96% in the 'ICM group' vs 97% in the 'DCM group'; P = 0.93). Furthermore, primary composite outcome (i.e. freedom from death or mitral regurgitation ≥ 2) at 1-year postoperatively was comparable between the study groups (94%in the 'ICM group' vs 87% in the 'DCM group'; P = 0.10). LV end-diastolic diameter 1-year after surgery was significantly reduced, as compared to preoperative values, in the 'DCM group' (P = 0.018), but not in the 'ICM group' (P = 0.058). Improvement of New York Heart Association functional class and reduction of serum levels of N-terminal pro-B natriuretic peptide at 1 year was comparable in both study groups.

Conclusions: Standardized relocation of both papillary muscles to correct FMR resulted in very satisfactory in-hospital and 1-year outcomes, in both ICM and DCM. DCM patients showed similar improvement in heart failure symptoms and LV re-remodelling compared to ICM patients. Subannular repair is developing towards a valid therapeutic option in heart failure patients presenting with severe FMR.