Purpose: Enzyme replacement therapy in infants with Pompe disease prolongs survival, decreases cardiomegaly, and improves muscle function. Because ectopy has been previously described in these patients, we sought to determine the prevalence and types of arrhythmias.
Methods: Thirty-eight children with infantile Pompe disease received enzyme replacement therapy in two open-label, multicenter, international, clinical trials. Data were reviewed on a retrospective basis. The corrected QT interval, ejection fraction, and indexed left ventricular mass were measured on a scheduled basis from electrocardiograms and echocardiograms. Arrhythmias were identified and characterized from electrocardiograms, ambulatory electrocardiograms, and point-of-care monitoring. Electrocardiogram and echocardiogram measurements were compared in children with and without arrhythmias.
Results: Seven children (18%) experienced arrhythmias. The QT interval, ejection fraction, indexed left ventricular mass, and rate of reduction of indexed left ventricular mass were not statistically different in those seven versus the other 31 children. Two children with life-threatening arrhythmias had among the highest combined baseline maximum indexed left ventricular mass and QT interval. Their arrhythmias occurred during severe metabolic stress from noncardiac illness.
Conclusions: There was a high incidence of arrhythmias in our cohort. The relationship of arrhythmias with enzyme replacement therapy, myocardial fibrosis, or simply longer survival is unknown. Therefore, further characterization of specific arrhythmia risk factors and continued vigilance regarding screening for arrhythmias in children receiving enzyme replacement therapy is warranted.