You can have a heart attack without knowing it
By William R. Condos, Jr., M.D., Medical Director, Cardiovascular Institute of the South/Lake Charles
The nation's longest-running heart study suggests that about one heart attack in four produces no symptoms - or at least none that the victim associates with a heart problem.
These so-called "silent heart attacks," however, are only the most extreme case of a still more prevalent condition called "silent ischemia" - a chronic shortage of oxygen - and nutrient-bearing blood to a portion of the heart. Both conditions put their victims at significant risk.
The cause of ischemia, silent or otherwise, is almost always atherosclerosis - the progressive narrowing of the heart's arteries from accumulations of cholesterol plaque. In most instances, this reduction in blood supply generates a protest from the heart - the crushing pain called angina. But in perhaps 25 to 30 percent of heart attack victims, there were no previous symptoms of these gradually developing blockages. The Framingham Heart Study, which followed 4,000 Massachusetts men for more than 40 years, found that 25 percent of their subjects' heart attacks go unnoticed until their annual EKGs detect their after-effects.
The absence of pain, however, doesn't mean an absence of damage. The heart has a built-in reserve capacity, allowing it to suffer a certain amount of scarring and weakening from a heart attack and continue to meet the body's needs. But further ischemia or another heart attack, even a mild to moderate one, may prove fatal because that reserve capacity is no longer there. Even those who survive another heart attack are at increased risk of becoming cardiac cripples, disabled by congestive heart failure or arrhythmias heartbeat irregularities.
There is no way of predicting absolutely who is a candidate for silent ischemia, but statistically, the greater the number of risk factors for coronary artery disease that you have, the more likely you are to be a candidate. Those risk factors include some you can't control - your age, sex and genetic predisposition to atherosclerosis - and those you can influence, like diabetes, high blood pressure, high blood cholesterol, smoking, lack of exercise and obesity.