Myocardial Perfusion in Patients with Primary Mitral Regurgitation Due to Mitral Valve Prolapse

Background: Mitral regurgitation (MR) is a common complication of mitral valve prolapse (MVP) and increases left ventricular (LV) preload, promotes LV remodeling and hypertrophy, but its impact on myocardial perfusion and coronary microvascular dysfunction remains unclear. Objectives: To assess myocardial perfusion using, for the first time, quantitative cardiac magnetic resonance (CMR) perfusion mapping in patients with significant MR due to MVP. Methods: Patients with significant primary MR, without coronary artery disease were prospectively enrolled and compared to age- and sex-matched controls without MR. All underwent 1.5T CMR including cine imaging, adenosine stress perfusion, native T1, native T2, extracellular volume (ECV) mapping and late gadolinium enhancement (LGE). Myocardial perfusion reserve (MPR) was calculated as the ratio of stress to rest myocardial perfusion. Results: In total 33 patients and 33 controls were included (age 56{+/-}13 vs. 58{+/-}12 years, 46% women in both groups). Patients with MR had increased LV mass and volumes, higher native T1 and ECV and a higher prevalence of LGE (36% vs 0%). No differences were observed in global myocardial perfusion at rest (0.88{+/-}0.27 vs. 0.85{+/-}0.30, p=0.52), at stress (2.6{+/-}0.56 vs. 2.8{+/-}0.73 ml/min/g, p=0.29) or for MPR (3.1{+/-}0.75 vs. 3.4{+/-}1.0, p=0.24). In age- and sex-adjusted linear regression, higher NYHA class was associated with lower MPR (0.60, p=0.04). Conclusion: In patients with significant MR due to MVP, myocardial perfusion appears preserved despite LV volume overload. However, lower MPR in symptomatic patients suggests that microvascular dysfunction may emerge in a more advanced disease stage.