Implications of myocardial strain in primary mitral regurgitation-a cardiovascular magnetic resonance study

Aims Chronic primary mitral regurgitation (MR) results in progressive left ventricular (LV) remodelling. Abnormal myocardial deformation (strain) can be present despite preserved ejection fraction (EF). Cardiovascular magnetic resonance (CMR) feature-tracking techniques allow assessment of global longitudinal strain (GLS) from routine cine images. The aim of this study is to evaluate the prognostic value of CMR feature tracking-derived GLS in patients with primary MR. Methods and results Consecutive patients undergoing CMR for chronic MR from January 2012 to June 2018 were enrolled. Patients with LVEF <50% were excluded. The composite primary outcome aiming to detect decompensation related to MR comprised (i) referral for mitral surgery owing to symptoms or LV systolic dysfunction or (ii) cardiovascular death. The secondary outcome was all-cause death. A total of 422 patients were followed for a median of 2.7 years, and the primary endpoint was met in 93 patients (34 patients reported symptoms at baseline). At multivariable analysis, GLS >= -16.6% was associated with primary outcome [hazard ratio (HR) 1.90, P = 0.01]. In moderate MR cohort, patients with GLS >= -16.6% had worse event-free survival, whereas there was no significant difference in mild or severe MR groups. GLS >= -16.0% remained associated with all-cause death after adjusting for other covariates including the MR severity (HR 2.24, P = 0.02). Conclusion In patients with primary MR with preserved systolic function, GLS was associated with our composite outcomes and all-cause death. GLS may serve as a marker of cardiac dysfunction in the patients with primary MR with preserved systolic function allowing identification of patients likely to decompensate during observation.