Can a defibrillator (implantable cardioverter defibrillator, or ICD) protect me from a heart attack?

An ICD is a device that is placed under the skin in the upper chest with a wire that leads into the heart. The ICD constantly senses the electrical activity of the heart, and if a dangerous heart rhythm should occur, called “ventricular tachycardia” or “ventricular fibrillation”, the defibrillator is ready to deliver treatment in the form of either rapid pacing or a shock. This device is life-saving for people who are at risk for a cardiac arrest due to these dangerous heart rhythms.

Physicians refer to a heart attack as a “myocardial infarction.” In a myocardial infarction there is a blockage in a coronary artery that is severe enough to cut-off blood flow to the portion of heart muscle that is served by that artery. The portion of heart muscle can die if the artery isn’t opened up right away. Symptoms of a myocardial infarction typically include chest tightness and shortness of breath. A myocardial infarction is a mechanical problem (a lack of blood flow), not an electrical problem, so an ICD does not prevent a heart attack, as it cannot prevent a blockage from occurring in a coronary artery.