Left ventricular diastolic function modifies clinical outcomes of mild mitral regurgitation

Current guidelines regard mild mitral regurgitation (MMR) as a benign condition and do not recommend risk stratification. Little is known about the interplay between MMR and left ventricular diastolic function (LVDF) status and their joint association with clinical outcome.

We included 4150 participants without HF at Visit 5 (2011-2013) of the ARIC (Atherosclerosis Risk in Communities) study. The association of MMR and LVDF with risk of HF and all-cause death were assessed by Cox proportional hazards model.

No significant association between MMR and unfavorable prognosis was observed neither in full cohort nor in normal LVDF subset. Only in the subset of those with impaired LVDF, MMR was significantly associated with increased risk of HF (HR = 2.50; 95 %CI: 1.30-4.86; P = 0.006) and composite outcome of HF and death (HR = 1.70; 95 %CI: 1.11-2.60; P = 0.014). Significant interactions were found between MMR and LVDF status on risk of HF and composite outcome (P for interaction = 0.031 and 0.012, respectively). MMR coexisting with impaired LVDF confers a significantly increased risk of HF (HR = 3.47; 95 %CI: 2.31-5.20, P < 0.001) and composite outcome of HF and death (HR = 1.95; 95 %CI: 1.50-2.55, P < 0.001).

MMR is associated with an increased risk of unfavorable prognosis only when coexisting with impaired LVDF. Serving as a clinical risk stratification tool, impaired LVDF defines a high-risk MMR subgroup. This subgroup requires intensified monitoring and targeted management to improve outcomes.