The story is all too common:
John, a 56 year-old accountant, sits in the living room watching a sitcom with his wife. John has not led a medically exemplary life, but the heart attack he had a month ago has given him an important wake-up call. "You were lucky this time, John," his doctor told him. "You've had substantial heart damage, but the old pump is still working well enough. If you straighten up your act you've got a good chance of seeing that new grandbaby get married some day."
So John has begun a strict diet, has begun exercising under the watchful eye of a local cardiac rehabilitation program, is taking all the medication his doctor has prescribed to help his heart heal and to help prevent another heart attack, and most importantly, has quit smoking. After only a month, he has already lost 5 pounds and is walking nearly a mile a day. He feels better - more fit and more energetic - than he has in years. He leans back in his easy chair and smiles. "You know," he says to his wife, "that heart attack may turn out to be one of the best things that ever happened to me."
She smiles back. "You are, no doubt, referring to the fact that you haven't had to do a lick of housework in over a month."
She expects a return chuckle from John - but all she gets is a soft gasp. She glances at her husband and is horrified by what she sees. John's eyes are wide with fright, and he is gasping for air. He feebly tries to stand, but collapses to the floor. Within seconds he is unconscious, and despite his wife's best efforts - and the efforts of the paramedics who arrive less than 10 minutes later - John dies.
This tragic scenario is played out in the United States alone nearly 1000 times each and every day. And like most loved ones of the victims of sudden death, John's wife no doubt will be told that he succumbed to a "massive heart attack" (the implication being that it was an unpredictable and unpreventable event,) "and despite the best post-heart-attack treatment that medicine has to offer, well, God works in mysterious ways."
While this sort of explanation may give some comfort to the widow - and while it may give some false comfort to the doctor as well - it is usually wrong. Most of these thousands of deaths are not due to another heart attack (that is, to another blockage of a coronary artery.) Instead, most are due to the sudden appearance of a lethal heart arrhythmia known as ventricular fibrillation. When ventricular fibrillation occurs, it usually occurs suddenly, without a shred of warning - often in mid-sentence. And unless the heart is defibrillated within a few minutes, death ensues. (Defibrillation is usually accomplished by placing the electrode "paddles" of a heart defibrillator on the chest and administering a high-voltage shock.)
Thankfully, ventricular fibrillation is an extremely rare occurrence in people with normal hearts. But in people who have suffered almost any form of heart muscle damage - heart attacks being by far the most common cause of heart muscle damage - ventricular fibrillation is disturbingly likely. (The heart muscle damage itself makes the heart electrically unstable, and produces the environment necessary for ventricular fibrillation to occur.) Indeed, the more muscle damage one has sustained, the higher the risk of having sudden death from this arrhythmia.
The large majority of the 300,000 people who die suddenly each year in the U.S. are people who have had prior heart attacks. Most of them, immediately prior to their sudden demise, seem to be doing quite well. There generally are no warning signs that can tip off either the patient or their doctors that sudden death is approaching.
There is a treatment that could prevent many of these sudden deaths - the implantable defibrillator. The implantable defibrillator is a pacemaker-like device that is implanted under the skin near the upper chest. It monitors the heart rhythm continuously, and if ventricular fibrillation occurs it automatically delivers a large shock to the heart, restoring the rhythm to normal. Often, the shock is delivered within a few seconds of the onset of the lethal arrhythmia. Implantable defibrillators have been used in patients for over 20 years, and have proven more than 99% effective in restoring the heart rhythm to normal, and in preventing sudden death.
