Implications of the Mitral Leaflet Coaptation Pattern on Clinical Outcomes in Patients With Functional Mitral Regurgitation

The classification of secondary mitral regurgitation (MR) is based on atrial functional MR (AFMR) or ventricular functional MR (VFMR) and volume changes, but the mitral leaflet coaptation angle also contributes to the MR mechanism. The clinical implications of the coaptation angle on cardiovascular (CV) outcomes have not been well evaluated. A total of 469 consecutive patients (265 AFMR vs 204 VFMR) with more than moderate MR were evaluated for the occurrence of heart failure, mitral valve operations, and CV death. The coaptation angle was assessed by measuring the internal angle between both leaflets at mid-systole using the apical 3-chamber view. A coaptation angle ≥130° was classified as leaflet flattening, and an angle <130° was classified as leaflet tethering. AFMR and VFMR were associated with higher frequencies of leaflet flattening and tethering, respectively. AFMR was more likely to be associated with older age, atrial fibrillation, and preserved ejection fraction, all of which were related to leaflet flattening. During a follow-up of 2.3 years, 83 patients had heart failure (17.7%), 21 patients underwent mitral valve operations (4.5%), and 34 patients died (7%). Compared with leaflet tethering, leaflet flattening was more significantly related to CV events, whereas CV event rates were less markedly different in A/VFMR. Irrespective of A/VFMR, leaflet flattening and atrial fibrillation were associated with a higher frequency of CV events. Adjusted analysis showed that leaflet flattening remained an independent predictor of CV events (hazard ratio 3.5, 95% confidence interval 1.11 to 4.88, p = 0.003), whereas A/VFMR did not. In conclusion, the leaflet coaptation angle in patients with functional MR could provide risk stratification superior to that of A/VFMR. Leaflet flattening appears to be associated with unfavorable clinical outcomes.