Precordial R wave height does not correlate with echocardiographic findings in boys with duchenne muscular dystrophy

Objectives: Cardiomyopathy (CM) is an inevitable consequence of Duchenne muscular dystrophy, and electrocardiographic changes, right ventricular hypertrophy in particular, have been proposed to serve as an early marker for CM. To evaluate this concept, we assessed the correlation between R wave height in lead V₁ and echocardiographic findings in boys with Duchenne muscular dystrophy. Methods: Serial echocardiograms and electrocardiograms (n = 800) were performed during each clinic visit in a cohort of 155 boys with Duchenne muscular dystrophy. Precordial R wave height in lead V₁ was measured. Echocardiographic parameters included ejection fraction (EF), shortening fraction, and left ventricular end-diastolic dimension. Data were analyzed using Pearson correlation and linear regression. Results: Ages ranged from 1.8 to 37.2 years (mean 14.7 ± 5.9 years). Seventy-one patients had CM and 318/800 echocardiograms had an EF < 55%. Older patients tended to have a lower EF, but there was no correlation between age and left ventricular end-diastolic dimension. R wave height in lead V₁ correlated poorly with both left ventricular end-diastolic dimension (r = 0.096, P =0078) and EF (r = 0.096, P =0088) for the whole cohort as well as those studies demonstrating an EF <55% (left ventricular end-diastolic dimension r = 0.089, P =12 and EFr = -0.044, P =94). No individual patient demonstrated significant correlation between R wave height in lead V₁ and left ventricular end-diastolic dimension or EF. Left ventricular end-diastolic dimension showed a moderate negative correlation with EF for the whole cohort (r = -0.394, P <.001) as well as those with an EF < 55% (r = -0.376, P <.001). Conclusions: The precordial R wave height in V₁ correlates poorly with the presence of depressed left ventricular function and is not prognostic for the development of CM. While not predictive for CM, the electrocardiogram remains vital to cardiac screening for boys with Duchenne muscular dystrophy due to risk for other cardiac manifestations such as arrhythmias.