Assessment of Cardiac Function in Adolescents With Duchenne Muscular Dystrophy: Importance of Neurohormones

Initial signs of cardiac dysfunction caused by Duchenne muscular dystrophy are usually detected during adolescence. However, decreased physical activity can allow better tolerance of decreased cardiac function. Mild myocardial dysfunction secondary to ischemic or idiopathic cardiomyopathy is accompanied by elevation of plasma levels of norepinephrine and atrial natriuretic factor. This is considered an adaptation to maintain adequate perfusion. We evaluated neurohormone levels in 17 adolescents (median age 14 years) with Duchenne muscular dystrophy and different degrees of ventricular dysfunction determined by echocardiography. All patients were asymptomatic. Electrocardiographic abnormalities were present in 14 of 17 (82%). Shortening fraction was below normal in 9 of 17 (53%). Norepinephrine plasma levels were elevated in 3, and all had normal atrial natriuretic factor levels. There was no association between fractional shortening and norepinephrine plasma level (P = .66). The majority of younger adolescents with Duchenne muscular dystrophy and abnormal ventricular function do not show signs of inadequate perfusion, as evidenced by normal measurements of neurohormones.