Sudden (Cardiac) Death

This describes a condition in which an individual collapses abruptly and unexpectedly and—unlike syncope—does not recover spontaneously. In the US, approximately 400,000 people die each year due to sudden cardiac death—more deaths than those combined from lung and breast cancer and AIDS.

There are many conditions that can cause sudden death such as bleeding from a tear in the aorta (the largest artery in the body) or in the brain. However, 90% of sudden (cardiac) death episodes are due to an abnormal heart rhythm called ventricular fibrillation (VF). In VF the heart rate in the lower chambers (ventricles) abruptly increases to > 250 beats per minute. Indeed the heart rhythm is extremely chaotic, the heart pump function thus ceases, the blood pressure drops and the patient collapses.

Unless prompt resuscitation with cardiac defibrillation (a shock) is delivered, death occurs within minutes. Many victims of sudden cardiac death have known heart disease (i.e., prior heart attack or myocardial infarction, or congestive heart failure) or are at high risk for heart disease.

Sudden cardiac death is not the same as a heart attack. In a heart attack, one of the coronary arteries blocks up and interrupts the blood flow to a specific region of the heart. In sudden cardiac death the heart rhythm abruptly becomes chaotic with ventricular fibrillation.

Patients with known severe heart disease are at increased risk for sudden cardiac death and should be evaluated for possible therapy with an implantable cardioverter defibrillator (ICD).