Abstract Intracardiac rhabdomyoma is the most common primary cardiac tumor in children. Most cases are associated with tuberous sclerosis complex (TSC). Most of them are asymptomatic in the neonate and do not require treatment. However, some develop cardiovascular symptoms such as arrhythmias, heart failure, and ventricular inflow/outflow tract obstruction in the neonatal period with early death. Many of these tumors are not candidates for surgical resection and medical management is limited. Treatment with mammalian target of rapamycin (mTOR) inhibitor is currently approved for the management of central nervous tumors and angiomyolipoma in TSC. Two patients with malignant arrhythmias related to nonsurgical multiple rhabdomyomas associated with TSC who were successfully treated with an mTOR inhibitor were described. Everolimus therapy showed significant regression of rhabdomyomas with rapid improvement of arrhythmias and heart failure prior to tumor shrinkage.