Here’s what heart attack survivors need to know to lower their chance of a future stroke.
First, the good news: The rate of first-time heart attacks has dropped by nearly half in the past 25 years. And heart attack survival rates have surged, thanks to improved treatments. The bad news? Compared to people without such a history, heart attack survivors not only face a higher risk of a second heart attack, they’re also more likely to have a stroke.
The risk of stroke is higher in the first year following a heart attack, especially during the first month. After a year, however, only the risk of ischemic stroke remains elevated, according to study in the July 2016 Stroke that tracked more than a quarter-million heart attack survivors over a 30-year period. (See “Types of stroke: Blockage vs. bleeding” for a primer on the different types.)
The heightened stroke risk isn’t surprising, given that heart attacks and ischemic strokes have nearly identical risk factors—namely, high blood pressure, diabetes, unhealthy cholesterol levels, lack of exercise, obesity, and cigarette smoking. But other factors can also come into play.
A particularly bad type of heart attack happens when a clot forms and completely blocks blood flow to part of the heart muscle. This can damage or scar the left ventricle, the heart’s main pumping chamber. “As a result, the heart may not contract normally, which can cause a blood clot to form,” explains Dr. Louis Caplan, professor of neurology at Harvard-affiliated Beth Israel Deaconess Medical Center. That new clot can then travel through the bloodstream and lodge in an artery that supplies a part of the brain. These so-called cardioembolic strokes are not common in this setting, occurring in about 3% to 4% of heart attack survivors, usually within 30 days of the heart attack. But the possibility is a reminder of why people need a comprehensive assessment to uncover and treat all their contributing factors to prevent cardiovascular problems in the future, says Dr. Caplan.
Rare but risky bleeding
During or after a heart attack, many people have a procedure to reopen the blocked artery (angioplasty), and to insert a tiny wire-mesh tube (stent) to prop the artery open. Then, they take one or more drugs to prevent clots from forming inside the stent, usually aspirin and clopidogrel (Plavix) or more powerful options, for up to a year and sometimes longer.
However, these drugs increase the risk of bleeding—including hemorrhagic strokes. This likely explains why, as the recent Stroke study showed, people face twice the risk of an intracerebral hemorrhage during the first year after a heart attack. But keep in mind that these events are very rare. Even when doubled, the risk is still low. Meanwhile, the drugs’ anti-clotting actions help to prevent another heart attack, which is far more likely than a bleeding stroke.
For heart attack survivors, the main message is to make sure you’re aware of all your personal risks and address them (see “Top 5 ways to prevent stroke”). And make sure you know the warning signs of a stroke; see www.health.harvard.edu/fast.
Types of stroke: Blockage vs. Bleeding
All strokes result from an injury to a blood vessel that limits blood flow to part of the brain. Without a constant supply of oxygen and nutrients provided by the blood, brain cells start to die. The resulting damage can leave a person unable to move, speak, feel, think, see, or even recognize other people. Ischemic strokes account for about 80% of all strokes; the other 20% are hemorrhagic strokes.