Assessment of Mitral Valve Area During Percutaneous Mitral Valve Repair Using the MitraClip System

Abstract

Background— Quantification of the mitral valve area (MVA) is important to guide percutaneous mitral valve repair using the MitraClip system. However, little is known about how to best assess MVA in this specific situation. Methods and Results— Immediately before and after MitraClip implantation, comprehensive 3-dimensional (3D) transesophageal echocardiography data were acquired for MVA assessment by the pressure half-time method and by two 3D quantification methods (mitral valve quantification software and 3D quantification software). In addition, transmitral gradients by continuous-wave Doppler (dPmean CW ) were measured to indirectly assess MVA. Data are given as median (interquartile range). Thirty-three patients (39% women) with a median age of 77.1 years (12.4 years) were studied. Before intervention, the median MVAs by the pressure half-time method, mitral valve quantification software, and 3D quantification software were 4.4 cm 2 (2.0 cm 2 ), 4.7 cm 2 (2.4 cm 2 ), and 6.2 cm 2 (2.4 cm 2 ), respectively ( P <0.001). After intervention, MVA was reduced to 1.9 cm 2 (0.7 cm 2 ), 2.1 cm 2 (1.1 cm 2 ), and 2.8 cm 2 (1.1 cm 2 ), respectively ( P =0.001). The median values for dPmean CW before and after intervention were 1.0 mm Hg (1.0 mm Hg) and 3.0 mm Hg (3.0 mm Hg; P <0.001), respectively. At discharge, the median dPmean CW was 4.0 mm Hg (3.0 mm Hg). In multivariate regression analyses including body surface area, the 3 different MVA methods, and dPmean CW , a post-dPmean CW ≥5 mm Hg was the best independent predictor of an elevated transmitral gradient at discharge. Conclusions— Transmitral gradients by continuous-wave Doppler are quick, feasible in all patients, and superior to direct peri-interventional assessment of MVA. A postinterventional transmitral gradient by continuous-wave Doppler of ≥5 mm Hg best predicted elevated transmitral gradients at discharge.