Abstract 17938: Evidence of Vicious Cycle in Mitral Regurgitation with Prolapse: Secondary Tethering Due to Primary Prolapse Demonstrated by 3-Dimensional Echocardiography Exacerbates Regurgitation

Abstract

Background: In patients with mitral valve prolapse (MVP), we often observe that non-prolapsed leaflets are tented (apically displaced) (Figure). We hypothesized 1) that secondary left ventricular (LV) dilatation due to primary mitral regurgitation (MR) causes this leaflet tethering and 2) that secondary tethering along with primary prolapse exacerbates malcoaptation and contributes to the severity of MR. Methods: 3DTEE was performed in 20 patients with posterior leaflet (PML) prolapse and intact anterior leaflet (AML) by TEE and surgical observation. 20 patients with cerebral infarction but without cardiac disease served as controls. From mid-systolic 3D zoom datasets, 10 parallel antero-posterior planes of the MV were obtained using i-slice mode (Q-LAB). In each view, area between leaflets and annular line was measured to obtain prolapse and tenting area, respectively. Prolapse/tenting volume of the whole leaflets was obtained as the product of inter-slice distance and the prolapse/tenting area in each plane. LV volume was also measured. MR volume was calculated as LV ejection volume minus aortic stroke volume by pulsed Doppler method. Results: 1) The AML tenting volume was significantly larger in patients with PML prolapse compared to controls (1.04±0.54 vs 0.58±0.14 ml/m2, p<0.001). 2) The AML tenting volume was significantly correlated with mid-systolic LV volume (r=0.61, p<0.001). 3) Sum of prolapse and tenting volume of the whole leaflets strongly correlated with MR volume (r=0.66, p<0.01) (r=0.38 and 0.48 for isolated prolapse and tenting volume, respectively). Conclusion: The results suggest that LV dilatation by primary MVP with MR causes secondary mitral leaflet tethering, which worsens valve leakage and constitutes a vicious cycle.