People who have a “mini stroke” appear to be at twice the risk of later having a heart attack. For people who have a mini stroke before 60 years of age, the risk of heart attack is up 15 times greater. These results, reported online March 24 in the journal Stroke by a research team from Mayo Clinic in Rochester, Minnesota, suggest that mini stroke (called in medical parlance a transient ischemic attack [TIA]) should be seen as a warning sign of heart disease, just as it is a recognized warning sign of permanent stroke.
What is a TIA?
A TIA is a temporary stroke that does not lead to lasting damage. A TIA occurs when portions of the brain are not supplied with blood for a short time. During both TIA and most permanent strokes, a blood vessel becomes blocked, cutting off blood supply to a portion of the brain. The blockage is usually the result of a blood clot. It a blood clot form in the blood vessel, it is called a thrombosis; if a clot floats “downstream” from another vessel, it is called an embolus.
During a TIA, the person displays all the signs and symptoms of stroke. However, in a TIA, the blockage clears before it causes permanent damage to the brain. This is the only difference between permanent stroke and TIA.
Warning Signs of Stroke or TIA
- Sudden numbness or weakness of the face, arm or leg, especially on one side of the body
- Sudden confusion, trouble speaking or understanding
- Sudden trouble seeing in one or both eyes
- Sudden trouble walking, dizziness, loss of balance or coordination
- Sudden, severe headache with no known cause
- Call emergency medical services (9-1-1 in many regions) immediately.
Because a TIA lasts for only a brief time, it is often called a “mini-stroke.” However, the American Stroke Association suggests that “warning stroke” might be a more appropriate term. TIA indicates that a person is at risk of stroke: About one-third of people who experience a TIA go on to have a stroke within a year.
A TIA is also a warning that heart disease -- specifically,coronary artery disease -- may exist. In people with coronary artery disease, blood vessels in and around the heart gradually lose their ability to supply the heart with blood. Researchers have known that people with a history of TIA are more likely to die of coronary artery disease. But up until now, doctors have not been able to quantify the risk of heart attack for people after a warning stroke.
What the Researchers Did
The Mayo Clinic research team examined the medical records of 456 people who had been diagnosed with a TIA between 1985 and 1994. The people’s average age was 72, and 57 percent were women. High blood pressure was present in nearly two-thirds of the , more than half smoked, and 75 percent were taking medication to prevent blood clots such as aspirin. The people were part of the Rochester Epidemiology Project, a population-based study of health problems in Olmsted, County, Minnesota that has been going on for more than 40 years.
Most of the people had other risk factors for heart disease. More than half (62 percent) had high blood pressure or smoked (55 percent), and 11 percent had diabetes.
What the Researchers Found
Slightly less than one percent of people in the study had a heart attack, about twice the rate in the general population. The median time span between the TIA and heart attack was 4.6 years. Importantly, people who had a heart attack after TIA were three times more likely to die than those who did not have a heart attack. This was true even after researchers factored in variables such as age, gender, and diabetes.
One of the most striking findings was the dramatically increased risk of heart attack – 15 times – among people who were younger than 60 years of age they had their TIA.
Those most at risk of heart attack were men, older people, and people who used cholesterol-lowering drugs. However, people taking these medications may have started with more advanced blood vessel disease, the researchers noted.
The presence of high blood pressure did not increase the likelihood of heart attack. Researchers suggested that this may be because blood pressure was being controlled effectively through medications.
What the Study Means
The researchers advised that screening for coronary artery disease may be useful even for people who have had a TIA, even if they show no indicators of heart disease. Just as a TIA has long been recognized as a precursor to stroke, they suggested, it should also be recognized as a potential precursor for heart attack.
"Physicians and other healthcare providers should be mindful of the increased risk for heart attack after TIA, just as they are about the increased occurrence of stroke," said Robert D. Brown Jr., M.D., M.P.H., principal investigator and chair of the neurology department at the Mayo Clinic in Rochester, Minn. "In the same way that we evaluate the patient to determine the cause of TIA and implement strategies to reduce the occurrence of stroke after a TIA, we should step back and consider whether a stress test or some other screening study for coronary-artery disease should also be performed after a TIA, in an attempt to lessen the occurrence of heart attack."
The researchers did note, however, that the study could be limited by the relative sameness of the population in Rochester, so study results might not apply to wider, more varied populations. In addition, heart attack risk could have been affected by other factors that the researchers did not measure.
American Stroke Association. (Jan/Feb 2009). TIA (Transient Ischemic Attack). Excerpted from Stroke: Why Rush? Available at http://www.strokeassociation.org/STROKEORG/AboutStroke/TypesofStroke/TIA/TIA-Transient-Ischemic-Attack_UCM_310942_Article.jsp
American Heart Association. (2011, Mar 24). Mini stroke doubles risk of heart attack. American Heart Association Rapid Access Journal Report. Available at http://www.newsroom.heart.org/index.php?s=43&item=1294
Burns, J.D., Rabinstein, A.A., Roger, V.L., Stead, L.G., Christianson, T.J.H., Killian, J.M., & Brown, Jr., R.D. (2011). Incidence and Predictors of Myocardial Infarction After Transient Ischemic Attack: A Population-Based Study Stroke 42: 935-940; published online before print as doi:10.1161/STROKEAHA.110.593723. Available at http://stroke.ahajournals.org/cgi/content/abstract/STROKEAHA.110.593723v1
What is the Rochester Epidemiology Project? Available at http://www.rochesterproject.org/