Cardiac involvement is common in tuberous sclerosis complex and is found in up to two thirds of patients. Cardiac rhabdomyomas (benign heart tumors) are another early sign of TSC. They may develop in the unborn baby and be picked up during routine antenatal scanning with ultrasound. The majority of afflicted patients are asymptomatic and their tumors regress spontaneously, often shrinking or completely disappearing as the child grows older.

Infants with cardiac rhabdomyomas have a 50% chance of having TSC. The other 50% have cardiac rhabdomyomas as an isolated finding.

Electrocardiograms (EKGs) are used to detect abnormal heart rhythms or arrhythmias. ECHO (cardiac ultrasound) is used to detect the presence of rhabdomyomas. Occasionally medical intervention with drugs is necessary to regulate an erratic heartbeat. Even more rarely surgical intervention is required to alleviate blood flow obstruction due to a rhabdomyoma.