Introduction: Myocardial fibrosis is crucial in many neuromuscular diseases with cardiac involvement, but non-invasive assessment is often difficult with traditional exams. Cardiac extracellular volume (ECV) was shown to indicate myocardial fibrosis and early cardiac involvement. With this study, our objective is to evaluate ECV measured with cardiac magnetic resonance (CMR) in patients with myotonic dystrophy type 1 (DM1) and 2 (DM2) as potential imaging biomarkers of subclinical cardiac pathology.
Materials and methods: We retrospectively analyzed 15 DM1 and 4 DM2 patients without apparent cardiac disease who had CMR at our center. The Mann-WhitneyU test was used to compare ECV with control groups from the literature. Spearman’s ρ was used for studying the associations
Results: Global ECV in DM1 patients (median 0.28; IQR 0.27-0.30) was significantly higher (p=0.004) than DM2 patients (median 0.23; IQR 0.21-0.24) and than that reported in literature in healthy subjects (p=0.006; median 0.25%; IQR 0.20-0.32). Septal ECV was significantly higher (p=0.01) in DM1 (median 0.28; IQR 0.26-0.30) than DM2 patients (median 0.22; IQR 0.21-0.23). Global ECV showed a strong, positive correlation with septal ECV (ρ=0.86, p <0.0001).
Discussion: We found a significant increase in global and septal ECV in patients with DM1. These values might suggest that DM1 patients present an increased cardiovascular risk, mainly due to cardiac fibrosis, even in absence of overt cardiac pathology at other cardiovascular exams. Physicians dealing with DM1 may consider CMR as a screening tool for the early identification of patients with increased cardiovascular risk. This work was supported by Fondazione Malattie Miotoniche.