Key result
Lead V1 R-wave height fails to predict cardiomyopathy in boys with Duchenne muscular dystrophy.
Why the study?
Electrocardiographic changes, particularly right ventricular hypertrophy measured by R wave height in lead V1, have been proposed as early markers for cardiomyopathy in Duchenne muscular dystrophy but their correlation with echocardiographic findings is unclear.
Cohort (n=155)
Answers are grounded in this paper and cite their sources.
R wave height in V1 lacks utility for CM screening in DMD; challenges prior proposals and leaves open need for validated ECG markers.
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 EF r = -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.
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Thrush et al. (2013) conducted a cohort in Duchenne muscular dystrophy (n=155). Precordial R wave height in lead V1 was evaluated on Correlation between R wave height in lead V1 and ejection fraction (r = 0.096, p=0.0088). Precordial R wave height in lead V1 correlated poorly with ejection fraction and is not prognostic for the development of cardiomyopathy in boys with Duchenne muscular dystrophy.
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