Abstract 4140203: Prognosis of Cardiovascular Magnetic Resonance Myocardial Characterization Among Individuals with Undifferentiated Non-ischemic Cardiomyopathy

Background: Contrast cardiovascular magnetic resonance (CMR) is the gold standard non-invasive method to characterize the left ventricular (LV) myocardium, yet its role in heart failure (HF) prediction in undifferentiated non-ischemic cardiomyopathy (uNICM, without etiology) is unclear. Aim: To evaluate CMR myocardial tissue characteristics [late gadolinium enhancement (LGE), native T1 mapping, and extracellular volume (ECV)] in HF diagnosis and prognosis among patients with uNICM. Methods: From 3583 consecutive patients referred for clinical CMR at our center (2019-2023), we identified patients with uNICM, with or without HF, based upon presence of: elevated T1 or ECV, non-ischemic LGE (e.g., mid-wall, subepicardial, transmural in patchy or non-coronary distribution), global LV dysfunction, and/or conclusion of uNICM. Individuals without HF were assessed for incident HF by physician medical record review. Multivariable (MV) regression models were used to assess the association between T1, ECV, and LGE with prevalent and incident HF. Results: Among 782 patients with uNICM, 379 had all CMR variables of LV structure and function (59±15 y; 36% F, 48% prevalent HF). Patients with HF had less favorable LV function and structure: ejection fraction (37 vs. 50%), mass index (71 vs. 64 g/m 2 ), end-diastolic volume index (121 vs 100 ml/m 2 ), T1 (1287 vs 1259 ms), and ECV (34 vs 31%), all p<0.001, except LGE (51 vs 59%, p = 0.150). In MV models, elevated T1 and ECV, but not LGE, were associated with prevalent HF ( Table ). In patients without prevalent HF (n=196), 33% patients developed HF over a median follow-up of 13 (IQR: 3-23) months. Elevated ECV conferred a >2-fold risk for incident HF (HR 2.77, 95%CI:1.36-5.66, p=0.005) in MV models ( Table , Fig ). Conclusion: Elevated ECV, possibly indicating diffuse fibrosis, is associated with both prevalent and incident HF in patients with uNICM referral for CMR. Larger studies may allow study of the prognosis of these measures in other hard outcomes.