Prognostic Impact of Ischemic Mitral Regurgitation Severity and Myocardial Infarct Quantification by Cardiovascular Magnetic Resonance

OBJECTIVES This study sought to evaluate the role of cardiac magnetic resonance (CMR) for the quanti fication of ischemic mitral regurgitation (IMR) and myocardial infarct size (MIS) in patients with ischemic cardiomyopathy (ICM). This study also sought to explore the interaction between IMR severity and MIS and its association with outcomes in patients with ICM. BACKGROUND IMR occurs secondary to a disease of the left ventricle and is associated with poor outcomes. The role of CMR for the evaluation and risk strati fication of patients with ICM and IMR remains uncertain. METHODS Consecutive patients with ICM who underwent baseline CMR were included. MIS was quanti fied on late gadolinium enhancement imaging as the proportion of left ventricular mass. IMR was quanti fied with CMR by calculating the mitral regurgitant fraction (MRFraction). Cox proportional hazards models were built to assess the association of IMR and MIS quanti fication with the combined endpoint of all -cause death or heart transplant. RESULTS We evaluated 578 patients (mean age: 62 +/- 11 years, 76% males). The mean left ventricular ejection fraction was 25 +/- 11%, with an MIS of 24 +/- 16% and MRFraction of 18 +/- 17%. Over a median follow-up time of 4.9 years, 198 (34%) patients experienced death or cardiac transplant. On multivariable analysis, after comprehensive medical risk score, subsequent revascularization, implantable cardioverter-de fibrillator insertion, and surgical mitral valve intervention were controlled for, the interaction of IMR severity and MIS emerged as a powerful predictor of adverse outcomes (p = 0.008). For patients with signi ficant IMR (MRFraction: $35%), the hazard ratio comparing moderate MIS (15% to 29%) versus small MIS ( <15%) was 1.51 (0.57 to 3.98), and the hazard ratio comparing large MIS ( $30%) versus small MIS was 5.41 (2.34 to 12.7). CONCLUSIONS Risk associated with IMR is more comprehensively described as an interaction between IMR severity and MIS. Further studies in patients IMR using comprehensive CMR evaluation are needed to verify whether this approach can improve patient selection and procedural outcomes to address IMR. (J Am Coll Cardiol Img 2020;13:1489 -501) (c) 2020 Published by Elsevier on behalf of the American College of Cardiology Foundation.