Impact of Chest Wall Conformation on the Outcome of Primary Mitral Regurgitation due to Mitral Valve Prolapse

Background: The possible influence of chest wall conformation on cardiovascular (CV) outcome of patients with mitral regurgitation (MR) due to mitral valve prolapse (MVP) has never been previously investigated. Methods: This retrospective study included all consecutive symptomatic patients with MVP and moderate MR who underwent exercise stress echocardiography at our institution between February 2014 and February 2021. Modified Haller Index (MHI; chest transverse diameter over the distance between sternum and spine) was noninvasively assessed. During the follow-up, we evaluated the occurrence of any of the following: (1) CV hospitalization, (2) mitral valve (MV) surgery, and (3) cardiac death or sudden death. Results: Four hundred and twenty-four consecutive patients (66.8 ± 11.5 years, 48.3% men) were retrospectively analyzed. Overall, MVP patients had concave-shaped chest wall (MHI = 2.55 ± 0.34) and were found with small cardiac chamber dimensions. During a mean follow-up time of 3.2 ± 1.7 years, no patients died, 55 patients were hospitalized due to CV events, and 20 patients underwent MV surgery. On multivariate Cox analysis, age (heart rate HR 1.05, 95% confidence interval CI 1.03-1.06), diabetes mellitus (HR 3.26, 95% CI 2.04-5.20), peak exercise-E/e' ratio (HR 1.07, 95%CI 1.05-1.09), and peak exercise-effective regurgitant orifice area (HR 2.53, 95% CI 1.83-3.51) were directly associated to outcome, whereas MHI (HR 0.15, 95%CI 0.07-0.33) and beta-blocker therapy (HR 0.26, 95% CI 0.19-0.36) showed strong inverse correlation. An MHI ≥2.7 showed 80% sensitivity and 100% specificity for predicting event-free survival (area under the curve = 0.98). Conclusions: Symptomatic patients with moderate MR due to MVP and MHI ≥2.7 have an excellent prognosis over a medium-term follow-up. Noninvasive chest wall shape assessment should be encouraged in clinical practice.