Abstract
Background: Duchenne muscular dystrophy (DMD) is the most common childhood form of muscular dystrophy.
The incidence of cardiomyopathy in DMD increases with age, so its early detection is important because
institution of cardioprotective medical therapies may slow adverse remodeling and attenuate heart failure
symptoms in these patients.
Objective: To assess the cardiac functions in children clinically suspected to have DMD.
Methods: Over a one-year period, 28 male children aged from 3 to 18 years old, who met the criteria for
diagnosis of DMD compared to 47 healthy controls children, were approached to participate in the study. The
included children were subjected to full clinical examination, and blood samples were collected to determine
creatinine phosphokinase (CPK), troponin I enzyme, myoglobin and lactate dehydrogenase (LDH) enzyme level.
Echocardiography and 12-leads electrocardiogram (ECG) were also done for children in both groups. Data were
analyzed using Independent-samples t-test, Mann-Whitney U, Chi square, and Fisher's exact test.
Results: The mean age of the cases group was 7.29±3.24 years versus 8.06±2.86 years for controls. In DMD
group, 25% had positive family history of DMD while 35.7% of them had positive consanguinity. All cases had
elevated CPK level while CPK level in controls was normal (p<0.0001). LDH level was elevated in 19 cases
(67.86%) of DMD while all controls children had normal LDH level (p<0.0001). Furthermore, the mean serum
myoglobin level of DMD patients was higher relative to that of healthy controls (39.39±7.25 versus 33.68 ±12.38
ng/ml respectively) (p=0.01). Echocardiography of our patients revealed that seven cases (25%) had low ejection
fraction (EF) and fraction shortening (FS). In addition, all controls children had normal EF (p<0.0001) and
normal FS (p<0.0001). Interestingly, ECG showed that 28.57% of cases had sinus tachycardia vs. 6.88% for
controls (p=0.0001). Prolonged QTc interval was present in 39.29% of cases (mean 431.39±43.60) while all
controls had normal QTc duration for age (mean of 415.17±25.2) (p<0.0001).
Conclusion: ECG manifestations in children with DMD in the form of sinus tachycardia and prolonged QTc
interval are an early alarm for developing cardiomyopathy before overt echocardiographic findings appear.