Abstract 11725: Low Left Ventricular Mass and Cardiomyopathy in Muscular Dystrophies: A Different Perspective on Potential Cardiac Mechanisms

Abstract

Introduction: Cardiomyopathy is a common complication in muscular dystrophy (MD) patients, though the mechanism is not clear. Retrospective data from adults with Duchenne muscular dystrophy suggest they have reduced LV mass compared to adults with other forms of non-ischemic cardiomyopathy. This raises the question whether pathologic hypertrophy contributes to the development of neuromuscular-associated cardiomyopathies. In this study, we hypothesized that MD patients have lower LV mass and associated changes in cardiac function as compared to healthy individuals. Methods: Utilizing cardiac magnetic resonance imaging (cMRI) data, a retrospective study was undertaken to compare LV mass, structure, and function between adults with MD and healthy age-, sex-, weight-matched controls from the Dallas Heart Study (DHS). Types of MD included dystrophinopathies, facioscapulohumeral MD, Freidreich ataxia, limb-girdle MD, myotonic dystrophy, and other rare MD. Approximately 50% of the MD patients were able to ambulate. MD patients were stratified into normal and reduced LVEF, defined as < 62% on cMRI, for further comparison. Statistical analysis was done using a two-sample, two-tailed t-test. Results: There were 339 MD patients (221 male) of mean age 40 and 417 DHS patients (187 male) of mean age 42. MD patients had a significantly lower LV mass, LV mass index, and LVEF than DHS adults. They also had significantly higher absolute and indexed volumes. In those with normal LVEF, all variables except LVESVi were significantly different from DHS. In those with reduced LVEF, all variables were significantly different from DHS. The results are summarized in Table 1. Conclusions: Collectively, MD patients have a reduced LV mass compared to healthy adults. In addition, MD patients with normal LVEF have lower LV mass than those patients with reduced LV function. Whether this observed decrease in LV mass represents cardiac hypoplasia or atrophy warrants further investigation.