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

Abstract

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. 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'). 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. 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.