Backgroud: Duchenne muscular dystrophy (DMD) is an inherited muscle disease. The heart is always affected, resulting in dilated cardiomyopathy. Some electrocardiogram (ECG) features have been previously described, but DMD association with ECG findings remains unclear.
Objectives: To evaluate prevalence of ECG changes, including 12-lead ECG and 24h-Holter in a group of DMD patients The prevalence of these changes were compared regarding left ventricular (LV) dysfunction.
Methods: This is a cross-sectional analysis from retrospective data of DMD patients from a single Brazilian center. All DMD diagnoses were confirmed by genetic testing. First, the prevalence of classical ECG changes was described including Q-waves considered abnormal when > 3 mm, R/S >1 in V1, in addition to basic parameters and intervals; 24h-Holter findings evaluated were presence of atrial or ventricular ectopic beats (relevant when > 5% of total) and occurrence of sustained or non-sustained tachycardia. Second, the prevalence of all individual ECG changes was compared in two groups according to LV dysfunction defined by ejection fraction < 50% (Simpson method) or presence of any segmental alteration. Fisher’s exact test was used to assess differences between groups. The study was approved by the local ethics committee. Results: Thirty-five young males were included, median age 19 (16–21) years, and 30 (86%) were wheelchair users. Median heart rate was 91 (85–99) bpm with sinus tachycardia in eight (23%). Eighteen (51%) patients with PR < 120 ms and six (17%) presented QTc > 450 ms. R/S > 1 in V1 was reported in 23 (67%) individuals. Q-wave in left anterior leads (V5/V6) in 17 (48%), lateral (I, AVL) 10 (28%), and inferior (II, III, AVF) 9 (26%). R/S > 1 in V1 plus Q-wave in V5/V6 (typical pattern) was present in 13 (37%). LV dysfunction was reported in 25 (71%) and included inferolateral abnormalities in 14 (40%). No differences were found in the prevalence of ECG findings between groups with or without LV dysfunction. Arrythmias recorded by Holter were quite frequent only in the LV dysfunction group in which ventricular arrythmia occurred in 7 (28%) compared to no patients with normal LV function (p = 0.06).
Conclusion: ECG changes were frequent in young males with DMD regardless of ventricular function. The most common ECG features were R/S >1 in V1, Q-waves in leads V5,V6, and short PR interval. Arrythmias were reported only in the group with LV dysfunction.