Abstract 15784: Left Ventricular Structural Remodeling and Cardiomyopathy in Duchenne Muscular Dystrophy Carriers

Abstract

Introduction: Duchenne muscular dystrophy (DMD) is an X-linked neuromuscular disorder. DMD-associated cardiomyopathy is the primary mode of premature death in the majority of male DMD patients, but the prevalence of cardiomyopathy and its clinical significance in female DMD carriers is less well characterized. Hypothesis: We hypothesized that a significant proportion of DMD carriers develop maladaptive left ventricular (LV) structural remodeling and cardiomyopathy over time. Methods: A cross-sectional study was undertaken comparing cardiac magnetic resonance imaging (cMRI) and cardiopulmonary stress test (CPX) parameters between DMD carriers and healthy age- and sex-matched controls from the Dallas Heart Study (DHS). Demographic data, cMRI parameters, and CPX parameters were collected retrospectively on 30 consecutive DMD carriers and 26 control DHS subjects. Results: Overall, DMD carriers had a significantly lower LVEF compared to DHS controls (58+8% vs 70+7%, p< 0.0001). The overall prevalence of reduced LVEF in DMD carriers (defined as LVEF <60%) was 63% compared to 8% in DHS controls. The volumetric variables indexed to body surface area (LVEDVi and LVESVi) were significantly higher in DMD carriers compared to control subjects (72+14 ml/m 2 vs 58+7, p< 0.0001; 31+10 ml/m 2 vs 17+5, p< 0.0001; respectively). LV concentricity was also significantly lower among all DMD carriers compared to DHS controls (3.10+0.65 g/mL 0.67 vs 3.73+0.79, p =0.002). LV concentricity was significantly lower in DMD carriers with reduced EF compared to controls (3.09+0.51 g/mL 0.67 vs 3.73+0.79, p = 0.012), while DMD carriers with preserved EF also had reduced concentricity compared to controls (3.12+0.86 vs 3.73+0.79, p = 0.054). Finally, peak VO 2 was lower in DMD carriers compared to DHS controls (23+6 ml/kg/min vs 25+4, p =0.076), though this difference did not reach statistical significance. Conclusions: Collectively, the data suggest that middle-aged female DMD carriers are at greater risk of developing left ventricular systolic dysfunction and cardiomyopathy associated with decreased exercise capacity. A possible mechanism driving the development of this cardiomyopathy is progressive, maladaptive left ventricular dilatation and cardiac atrophy.