It occurs instantly or shortly after symptoms appear. The most common reason for patients to die suddenly is cardiovascular disease, in particular coronary heart disease. About half of all deaths from coronary heart disease are sudden and unexpected, regardless of the underlying disease. Thus half of all deaths due to atherosclerosis of the coronary arteries are sudden. So are half of deaths due to degeneration of the heart muscle, or to cardiac enlargement in patients with high blood pressure.
Sudden death is a major health problem.
About 225,000 sudden cardiac deaths occur each year among U.S. adults. All known heart diseases can lead to sudden cardiac death. Some are due to extreme slowing of the heart. All these events are called life-threatening arrhythmias . While a heart attack may cause cardiac arrest and sudden cardiac death, the terms aren't synonymous.