Abstract
BACKGROUND: Anti-MDA5 antibody-positive dermatomyositis (anti-MDA5 Ab+ DM) is increasingly recognized to involve the heart, yet the prevalence and phenotype of cardiac involvement remain insufficiently characterized. This study aimed to determine the utility of cardiac magnetic resonance (CMR) for detecting myocardial involvement (MI) in patients with anti-MDA5+ DM. METHODS: We prospectively included 42 anti-MDA5+ DM patients (male: 23, median age: 45 years) and 29 age- and gender-matched healthy controls (HCs). All participants underwent CMR to evaluate left ventricular function, native T1 and T2 value, and late gadolinium enhancement (LGE). RESULTS: Patients with anti-MDA5+ DM exhibited significantly reduced left ventricular ejection fraction (LVEF) compared to HCs (P<0.001). They also had elevated myocardial T1 (P<0.001) and T2 (P<0.001) values. LGE was detected in 35.7% of patients. Compared to the LGE-negative group, patients with LGE-positive findings had higher creatine kinase myocardial band (CK-MB) levels (P<0.001) and lower cardiac index (CI, P<0.05). We stratified anti-MDA5+ DM patients into subgroups according to predefined thresholds for the biomarkers. The inflammatory marker-positive subgroup showed significantly increased left ventricular end-diastolic volume index (LVEDVI) and reduced CI compared to the negative subgroup (LVEDVI: 64.0±17.1 vs. 54.8±10.1 mL/m(2), P=0.047; CI: 2.6±0.5 vs. 3.0±0.6 L/min/m(2), P=0.006). LVEDVI (r=0.520, P<0.001) correlated with ferritin (FER) levels and LVEF demonstrated a moderate negative correlation with FER levels (r=-0.492, P<0.001). CONCLUSIONS: Left ventricular involvement is highly prevalent in anti-MDA5+ DM patients, as evidenced by CMR. The study reinforces CMR as a valuable diagnostic tool for MI in anti-MDA5+ DM patients.