[Enzyme replacement therapy in a boy with infantile Pompe disease: cardiac follow-up]

Pompe disease is an autosomal recessive glycogen storage disorder caused by acid-alpha-glucosidase deficiency. The infantile form is usually fatal by 1 year of age in the absence of specific therapy. We report the cardiac follow-up of a 4-month-old boy treated with enzyme replacement therapy (ERT) for 8 months. The patient had no cardiac failure at the age of 1 year. Before starting ERT, ECG showed a shortened PR interval, with huge QRS complexes and biventricular hypertrophy; echocardiography demonstrated major hypertrophic cardiomyopathy. The QRS voltage (SV1+RV6) decreased from 13 to 2.9 mV after 32 weeks of ERT, suggesting a progressive reduction of cardiac hypertrophy and intracellular glycogen excess. The PR interval increased from 60 to 90 ms. A block of the right bundle branch appeared after 13 weeks of treatment. The indexed left ventricular mass decreased from 240 to 90 g/m2 after 30 weeks of ERT. The left ventricular ejection fraction decreased transitorily between the 5th and the 15 th weeks of treatment. In summary, ERT is an efficient therapeutic approach for the cardiomyopathy of infantile Pompe disease. However, the possible occurrence of a right bundle branch block and a transitory alteration in the ejection fraction highlight the importance of cardiac follow-up.