If you have one heart attack, what are the chances you will have another? As former Vice-President Dick Cheney—who suffered his fifth heart attack this week—probably knows by now, the odds are high. And the chance you will suffer any heart attack increase with age. For someone in the age bracket from 65 to 74, which includes the 69-year-old Cheney, the odds a person has experienced a heart attack are 1 in 9.44.
For 325,000 people every year, the crushing chest pain and shortness of breath that often accompany a heart attack are not new sensations. That’s because more than one third of the heart attacks that occur every year (325,000 out of 945,000) happen to people who have already had at least one before.
In fact, previous myocardial infarction, the medical term for heart attack, is one of the biggest risk factors for future myocardial infarction (called “MI” for short). Among patients who survive their first MI, 21% of men and 33% of women will experience another one within six years. This high rate of recurrence makes sense because coronary heart disease is rarely limited to just one blood vessel.
Coronary heart disease, the generic term for narrowing of the arteries that deliver blood directly to the heart, is responsible for most heart attacks. Over time, fat and cholesterol build up on the walls of the coronary arteries, forming “plaques” that eventually calcify. When the plaques get thick enough, the affected arteries become too narrow for blood to pass through them. Plaques can also break off and lodge downstream, or they can bleed and form a clot that obstructs the artery. In any case, when blood cannot flow through a coronary artery, the portion of the heart that relies on the blocked artery for blood supply suffers damage—a myocardial infarction.
Although coronary heart disease (CHD) affects arteries at different rates, more than one artery is usually diseased, which explains the high likelihood of recurrent MI. Almost 17 million American adults carry a diagnosis of CHD, accounting for the pretty high odds (1 in 171.3) that a person aged 35 or older will suffer a heart attack in a year. The odds increase dramatically with age: there is a 1 in 5.4 chance that a person 85-94 has had a heart attack—almost 10 times the odds for a person aged 45-54 (1 in 52.63). The odds that any person 35 or older will have a recurrent MI in a year are 1 in 492.6.
Because the chances of dying from a second heart attack are significantly increased compared with the first MI (recurrent MIs account for 14-30% of all hospitalizations for heart attacks, but they are responsible for 30-50% of deaths caused by MIs), preventing subsequent attacks is very important. Patients are often told to focus on six major modifiable risk factors: high cholesterol, high blood pressure, obesity, diabetes, inactivity, and cigarette smoking. Reducing these risks can be achieved with a combination of medications and lifestyle modification.
Four drugs have proven to be effective in preventing future MIs. Aspirin helps prevent the formation of a blood clot that might clog up a coronary artery. ACE inhibitors (lisinopril, for example) not only help reduce high blood pressure, but are also thought to prevent the area of infarction from spreading. Beta blockers (such as metoprolol or atenolol) improve survival, in part by easing the heart’s workload. Finally, statins (like the popular, as-seen-on-TV Lipitor™) decrease LDL, or “bad cholesterol,” to help slow plaque buildup in the arteries. The American College of Cardiology along with the American Heart Association recommends that heart attack patients should take all four of these medications indefinitely.
Popping pills won’t fix everything—patients can change certain behaviors to help themselves as well. The single best thing they can do is quit smoking cigarettes. Within one year of quitting, former smokers’ risk of recurrent MI is cut in half, and by two years, their risk is the same as that for nonsmokers. Weight loss is also important, since obesity (in particular, a high waist-to-hip ratio—i.e. bigger waist, smaller hips) has been associated with higher rates of heart failure and repeat coronary events. Diabetics need to pay careful attention to their blood sugar after a heart attack, since high blood sugar is linked to worse outcomes.
Coronary heart disease is already responsible for one out of every five deaths in the United States—by far the most common killer. When patients are lucky enough to survive their first MI, they can work with their doctors to reduce their risk so that crushing chest pain and shortness of breath never get a second chance.