Functional versus anatomical method for defining the LV base by CMR in Barlow's disease: what is the best approach for quantifying mitral regurgitation?

Abstract Introduction In bileaflet mitral valve prolapse (BMVP), Doppler-based echocardiographic quantification techniques of mitral regurgitation (MR) severity may be inaccurate and volumetric assessment by Cardiac Magnetic Resonance (CMR), might better reflect volume overload. However, the optimal method for measuring Left Ventricular End Systolic Volume (LVESV) in the presence of severe prolapse is unknown. Indeed, at end-systole, the LV base can either be defined at the annulus (functional method) or at the leaflets’ level (anatomical method). We aimed to compare these two methods and their association with post-surgical cardiac remodeling Material and Methods Consecutive patients referred for evaluation of MR were assessed with echocardiography and/or CMR at baseline and patients were invited to repeat CMR within 12 months of surgical repair/replacement (when performed). Only patients with BMVP were analyzed. Mitral regurgitant volume was calculated using a direct quantitative method with LVESV measured either at the annulus or at the leaflets, and the respective correlations with the absolute reduction in LV end-diastolic volume after surgery were compared. Results Among 33 BMVP patients included, 14 eventually underwent surgery and 11 had both pre- and post-operative CMR. Pre-operative LV ejection fraction was 59.5±5.6% in the functional group versus 49.1±8.2% in the anatomical group. The mitral regurgitant volume (MRV) tended to be higher using the functionnal method, with a mean difference of 23.8 ± 14.5 ml compared to the anatomical method (Figure 1). Only the anatomical measure of the MRV was significantly correlated with post-operative left ventricular remodeling (r = 0.65, p < 0.05) (Figure 2). Conclusion Our results indicate a better ability to predict post-surgical left ventricular remodeling with the anatomical compared to the functional method in Barlow's disease. The anatomical method may be the method of choice for the quantification of MR severity with CMR in BMVP but these preliminary results need to be confirmed in a larger cohort.