Rapid regression of left ventricular outflow tract rhabdomyoma after sirolimus therapy.

The neonatal presentation of cardiac rhabdomyomas varies in severity from severe outflow tract obstruction to minimal cardiac dysfunction. The natural history for these lesions is spontaneous regression in the majority of cases. We describe a newborn boy with severe left ventricular outflow tract obstruction secondary to a large rhabdomyoma. The tumor infiltrated the paraaortic area and extended around the origin of the right coronary artery, making surgical resection challenging. Oral sirolimus therapy resulted in a rapid regression of the tumor and alleviation of outflow tract obstruction within 1 month of treatment. This is the first report of sirolimus therapy in alleviating critical left ventricular outflow tract obstruction in this condition.