Many cardiac disorders can be inherited, including arrhythmias, congenital heart disease, cardiomyopathy, and high blood cholesterol. Coronary artery disease leading to heart attack, stroke, and heart failure can run in families, indicating inherited genetic risk factors.
Genetics can influence the risk for heart disease in many ways. Genes control every aspect of the cardiovascular system, from the strength of the blood vessels to the way cells in the heart communicate. A genetic variation (mutation) in a single gene can affect the likelihood of developing heart disease. For example, a genetic variation can change the way a particular protein works so that the body processes cholesterol differently, increasing the likelihood of blocked arteries. Genetic variations are passed from parents to children in the DNA of the eggs and sperm. The parents’ genetic code is then copied into every cell of a child’s body during development.
When a family member is diagnosed with heart disease or a heart disorder, other family members are encouraged to undergo screening for risk factors and early stage disease that may not yet produce symptoms.
Inherited conditions that lead to arrhythmias and sudden cardiac death are particularly well understood. Hypertrophic cardiomyopathy and arrhythmogenic right ventricular cardiomyopathy (ARVC) both can cause deadly arrhythmias. There are a number of inherited disorders that can cause arrhythmias and sudden cardiac death. Some of these are very rare. The more common ones include:
- Atrial fibrillation: a common arrhythmia that increases the risk for stroke
- Brugada Syndrome: a genetic disorder of the heart rhythm that can cause ventricular fibrillation and sudden cardiac arrest
- Catecholaminergic polymorphic ventricular tachycardia: a disorder of the calcium channels in the heart muscle, resulting in problems with electrical signalling and irregular heartbeats, especially during exercise
- Long QT Syndrome: a prolonged electrical recovery phase (QT interval) of the heartbeat that can result in rapid, chaotic beats
- Short QT Syndrome: a shortened QT interval that can result in life-threatening arrhythmias
Medical screening is recommended for family members of a sudden cardiac death victim. If relatives of the deceased are thought to carry an inherited disorder that puts them at similar risk, preventive treatment options are available. These include drug therapies and implantable devices. (See arrhythmias for more information on treatment options.)