Re-examination of the Electrocardiogram in Boys With Duchenne Muscular Dystrophy and Correlation With Its Dilated Cardiomyopathy

Duchenne muscular dystrophy (DMD) results in dilated cardiomyopathy (DC). Characteristic electrocardiographic (ECG) changes include short PR interval, right ventricular hypertrophy (RVH), prolonged QTc interval, and prominent Q waves in leads I, aVL, V₅, and V₆ or in leads II, III, aVF, V₅, and V₆. We re-examined the prevalence and correlation of ECG changes with DC in DMD. Electrograms of 115 patients with DMD were evaluated. DC was defined as an echocardiographic ejection fraction <55%. PR interval and RVH were based on age-based normal values. Abnormal Q waves were ≥4 mm. Abnormal QTc interval was ≥450 ms. ST-segment depression was defined as >0.5 mm. Fisher's exact test evaluated significant differences between groups and logistic regression determined whether number of ECG changes predicted DC. Forty had DC. No significant differences existed between the number of ECG changes in DC and non-DC groups (p = 0.279). Distribution of findings included short PR interval (43%), RVH (37%), prominent Q waves in leads V₅ (34%) and V₆ (33%), prominent Q waves in leads I, aVL, V₅, and V₆ (3, 1 with DC), prominent Q waves in leads II, III, aVF, V₅, and V₆ (9, 4 with DC), long QTc interval (0), ST depression (2, 1 with DC), and flat/biphasic ST segments (38, 15 with DC). In conclusion, ECG changes are similar in patients with DMD regardless of presence of DC. Previously reported characteristic ECG changes are seen in a minority of DMD cases. The most common findings are short PR interval and RVH. Prominent Q waves in leads II, III, aVF, V₅, and V₆ are more likely.