HYPERTROPHIC CARDIOMYOPATHY ASSOCIATED WITH DEXAMETHASONE THERAPY FOR BRONCHOPULMONARY DYSPLASIA

The potential induction of cardiac effects by high-dose dexamethasone therapy was evaluated prospectively in 13 respirator-dependent infants with bronchopulmonary dysplasia by means of two-dimensional and M-mode echocardiography. The initial divided dose of dexamethasone was 500-mu-g/kg per day, tapered progressively for as long as 6 weeks. Evaluations were made before treatment and at 3, 7, 14, 21, 28,35, and 42 days after the start of dexamethasone therapy. This regimen was associated with a significant (p < 0.01) increase in thickness of the interventricular septum (2.60 +/- 0.09 to 4.00 +/- 0.16 mm), diastolic left ventricular free wall (2.80 +/- 0.13 to 4.06 +/- 0.20 mm), and diastolic right ventricular free wall (1.55 +/- 0.08 to 2.02 +/- 0.12 mm). In addition, seven dexamethasone-treated infants but no control infants had systolic anterior motion of the mitral valve (p < 0.001). These effects were transient, reached their maximal degree by the third week of treatment, and approached pretreatment conditions by the sixth week of treatment. Ejection fraction was not affected; heart rate and mean arterial pressure were transiently increased during dexamethasone therapy. We conclude that a transient absolute myocardial hypertrophy is associated with dexamethasone therapy in infants with bronchopulmonary dysplasia. The mechanism or mechanisms through which this hypertrophy arises and the cardiopulmonary implications are unclear.