The impact of intraoperative residual mild regurgitation after repair of degenerative mitral regurgitation

Objectives: During degenerative mitral repair, surgeons must decide if further repair is warranted for residual mild mitral regurgitation. We examined the incidence of mild mitral regurgitation, late echocardiographic and clinical outcomes, and influence of surgical experience in decision making. Methods: From April 2004 to June 2018, 1155 of 1195 patients with pure degenerative disease underwent repair (97% repair rate). Propensity score matching was performed between patients with trace/no mitral regurgitation and patients with mild residual mitral regurgitation. Late echocardiographic outcome and freedom from reoperation were compared using competing-risks models. A comparison of outcomes of the referent surgeon (89.8% of repairs) with all other surgeons was performed. Results: Mild mitral regurgitation was present in 73 patients (6%). Propensity score–matched analyses compared 69 patients with mild mitral regurgitation with 198 patients without mitral regurgitation. Late moderate or greater mitral regurgitation was higher in those with mild mitral regurgitation than in those with no mitral regurgitation (17% vs 7%, P =.033), as was late moderate-severe or greater mitral regurgitation (6% vs 1%, P =.016). Ten-year freedom from reoperation was low in both groups (99.5% no vs 96.9% mild; P =.10). The referent surgeon had fewer patients with mild residual mitral regurgitation (6% vs 11%, P =.027) and less progression of mitral regurgitation compared with other surgeons (late moderate or greater mitral regurgitation 6% vs 15%, P =.002). Conclusions: Residual mild mitral regurgitation was uncommon, and late progression to moderate or greater mitral regurgitation was rare and never led to late mitral reoperation. Experienced surgeons may be better able to determine repairs likely to remain stable, and most mild residual mitral regurgitation does not require re-repair.