Longitudinal Trajectories of Secondary Mitral Regurgitation in Nonischemic Dilated Cardiomyopathy

Background: In nonischemic dilated cardiomyopathy (NICM), the severity of secondary mitral regurgitation (SMR) is dynamic, depending on loading conditions and the effect of guideline-directed medical therapy (GDMT). However, the longitudinal trajectories of SMR and their prognostic implications remain insufficiently explored. We aimed to define the long-term trajectories of SMR and their prognostic impact in NICM. Methods: We retrospectively analyzed 764 NICM patients who underwent serial echocardiographic evaluations over a median follow-up of 9 (4-15) years. The longitudinal trajectories of SMR were identified using a latent class mixed model. Phenotypic characteristics and cardiovascular outcomes (all-cause death [D], heart transplant [HT], left ventricular assist device implantation [LVAD]) associated with SMR trajectories were investigated. Results: Secondary mitral regurgitation trajectories identified for patients with baseline no to mild SMR (n = 440) were no progression (76.2%), mild worsening (10.2%), and severe worsening (13.6%). In patients with baseline moderate to severe SMR (n = 324), trajectories included persistent moderate to severe SMR (24%), mild improvement (8%), and strong improvement (68%). Smaller left atrium was associated with both mild and strong SMR improvement, while absence of left bundle branch block and New York Heart Association functional class