Prevalence of Cardiac Disease in Duchenne Muscular Dystrophy Patients by Age: A Cardiac Magnetic Resonance Natural History Study
Background: Duchenne muscular dystrophy (DMD) patients universally develop cardiomyopathy and considered a dilated cardiomyopathy. Cardiac magnetic resonance imaging (CMR) revealed LGE prior to ventricular dysfunction. Various novel trials including gene therapy are ongoing with growing interest on how it impacts the heart. There is paucity of CMR data at a given age. A major barrier is lack of age specific data. We therefore, sought to determine the prevalence left ventricular (LV) dilation by endiastolic volume (LVEDV), ejection fraction (LVEF) and late gadolinium enhancement (LGE) status at a given age.
Methods: Retrospective review of CMR studies in DMD. LV dilation is defined as LVEDVi z-score > 2, abnormal LVEF (<55%) and LGE (yes or no). Patients were group by age in one year interval (given smaller numbers patients < 7 years were grouped together as were those ? 20 years).
Results: 683 DMD patients were identified with average of 48.8±24 (range 19-94) patients per group divided into 14 age groups. Mean age was 12.3±4 (range 4-39 years). LV dilation was uncommon even in older age patients (mean 1.9±2.6%, range 0-8.7%). LVEF is rarely abnormal before 10 years (<5%) but increased with age (69.9% in the ? 20 year group). In all groups mean % LVEF < 55% is 24.6±20.6% (range 2.5-69.9). LGE can be found as young as 6.5 years but uncommon before age 10 years (<10%), increased to nearly 20% by age 10 years and incrementally increased to >50% after 11 (4.3% < 7 year group to > 80% by 18 years).
Conclusion: This is the first and largest CMR natural history study by individual age showing low prevalence of LV dilation in DMD population. LVEF abnormality and LGE is uncommon before 10 years but increased with age. Future longitudinal assessment is ongoing to determine rate of change at a given age, quantifying LGE and myocardial strain for earlier cardiac disease assessment and modeling for disease progression at different age.