Risk factors for SCA include:
Low ejection fraction or weak heart muscle
Prior heart attack
Heart failure
Abnormal heart rate or heart rhythm (arrhythmia)
Family history of arrhythmia
Family history of sudden cardiac death
Congenital heart defects
Hypertrophic cardiomyopathy (a thickened heart muscle that especially affects the ventricles)
Viral infection in the heart
History of syncope (fainting)
Coronary artery disease (CAD) and risk factors for CAD, including smoking, high blood pressure, diabetes, high cholesterol, obesity, and a sedentary lifestyle
Significant changes in blood levels of potassium and magnesium (e.g., from using diuretics)
Recreational drug use.