Abstract 4365303: Cardiac MRI Characterization of Non-Dilated Left Ventricular Cardiomyopathy: A Comparative Study with Dilated Cardiomyopathy

Introduction: Non-dilated left ventricular cardiomyopathy (NDCM) is defined by impaired systolic function with preserved left ventricular volume. While distinct from dilated cardiomyopathy (DCM), its cardiac magnetic resonance (CMR) profile and clinical implications remain poorly characterized. Hypothesis: We hypothesized that NDCM has a unique cardiac magnetic resonance (CMR) profile distinct from DCM, reflecting differences in myocardial tissue characteristics and clinical outcomes. Methods: We retrospectively analyzed CMR data from 73 patients with NDCM (defined as LVEF <45% and LVEDVi <114 mL/m 2 in men or <98 mL/m 2 in women) and 78 patients with DCM. CMR parameters included native T1 and T2 mapping, biventricular ejection fraction, global longitudinal strain (GLS), stroke volume index (SVI), late gadolinium enhancement (LGE). Outcomes included all-cause mortality and heart failure rehospitalization. Results: Compared with DCM, patients with NDCM had significantly lower native T1 values (1311±45 vs. 1340±57 ms, p<0.01), BNP levels (408±534 vs. 849±1195 pg/mL, p<0.01), and stroke volume index (29±7 vs. 36±11 mL/m 2 , p<0.01), along with better global longitudinal strain (–9±4% vs. –8±4%, p<0.05). Left ventricular ejection fraction (LVEF; 32±8% vs. 25±7%, p<0.01) and body mass index (BMI; 23±6 vs. 22±5 kg/m 2 , p<0.05) were also significantly higher in the NDCM group. The frequency of late gadolinium enhancement (LGE), right ventricular ejection fraction (RVEF), T2 values, and left atrial volume index did not differ significantly between the two groups. Kaplan–Meier analysis revealed no significant differences in overall survival or heart failure rehospitalization (Figure). Conclusions: NDCM demonstrates a distinct CMR profile from DCM, with reduced markers of myocardial fibrosis and relatively preserved systolic function. Despite these imaging differences, clinical outcomes were similar between the two groups. CMR serves as a valuable tool in differentiating cardiomyopathy subtypes, although further studies are needed to clarify the prognostic relevance of the NDCM.