Each day in the United States, more than 930 lives are lost to sudden cardiac death (SCD). Every 90 seconds, this insidious killer claims another victim. Sudden cardiac death is the leading cause of natural deaths in the United States, taking more than 335,000 lives each year, more than are lost to lung cancer, breast cancer and AIDS combined. Yet, because there are few warning signs or symptoms to identify people at risk, and since SCD is by definition fatal, there are few survivors to spread the word about this devastating killer. Until SCD hits close to home, most people usually are unaware of its prevalence and the danger that it poses, even to young, seemingly healthy people. It often strikes adults in their mid-30s to mid-40s, though it can strike teenagers as well as senior citizens.


Sudden cardiac death, also called sudden cardiac arrest (SCA), is a term used to describe a situation in which the heart stops working, abruptly and without warning, so no blood can be pumped to the rest of the body. It is responsible for more than half of all heart disease deaths in this country. And, while overall death rates for heart disease are decreasing, those from sudden cardiac death continue to increase. Sudden cardiac death is not a heart attack, which occurs when a blockage in a blood vessel interrupts the flow of oxygen-rich blood to the heart, causing heart muscle to die.

Sudden cardiac death occurs when the heart’s electrical system malfunctions. The most common cause of SCD is a heart rhythm disorder, or arrhythmia, called ventricular fibrillation (VF) (a quivering of the heart’s lower chambers) or ventricular tachycardia (extremely rapid but ineffective beating of the heart’s lower chambers).

This irregular heart rhythm causes the heart suddenly to stop pumping blood to the rest of the body. If blood does not flow to the brain, it becomes starved of oxygen, and the person loses consciousness in a matter of seconds.

Death can occur within ten minutes unless CPR is administered and an emergency shock is delivered to the heart with a defibrillator to restore its normal rhythm. Survival is directly linked to the amount of time between the onset of sudden cardiac arrest and defibrillation. A victim’s chances of survival are reduced by seven to ten percent with every minute of delay until defibrillation. The VF sudden cardiac arrest survival rate is only two to five per cent if defibrillation is provided more than twelve minutes after collapse. It is estimated that about 95% of sudden cardiac arrest victims die before reaching the hospital.