Pompe disease (acid maltase deficiency, glycogen storage disease type II) is a rare progressive autosomal recessive disorder caused by a deficiency of lysosomal hydrolase acid alpha-glucosidase. Historically, infantile-onset Pompe disease presents with cardiomegaly, hepatomegaly, weakness and hypotonia leading to death caused by cardiorespiratory failure in the first year of life. Enzyme replacement therapy has recently become available and has been shown to be effective in prolonging survival and improving respiratory performance. In this article, we report a case of infantile-onset Pompe disease successfully managed with enzyme replacement therapy during the critical period. We would like to highlight the occurrence of sudden cardiac arrest in our patient during the early course of enzyme replacement therapy, which has not been reported before. A novel mutation was also identified in the family.