Nov. 11, 2011 -- The tiny lapses in blood flow to the brain commonly called mini strokes aren't fatal, but can shorten your life, according to new findings from Australian researchers.
Also known as TIAs, transient ischemic attacks can result from blood clots or from narrowed or injured vessels that supply blood to the brain. The resulting stroke-like symptoms typically resolve after an hour or two. Scientists have long known TIAs boost the risk of stroke. However, they didn't have any large, recent studies calculating their toll on longevity.
A team led by Melina Gattellari, a senior lecturer in public health and community medicine at the University of New South Wales, on Thursday published estimates of TIAs' life-shortening effects. After one year, a TIA shaved 4 percent off life expectancy. By the time 9 years had passed, the TIA shaved away about 20 percent.
Unfortunately, Gattellari said, she couldn't translate those statistical reductions into "lost years."
TIAs had a minimal effect on the longevity of people under 50. However, survival rates progressively declined as TIA patients aged. In addition, the older that patients were when they suffered one of these brain episodes, the worse their survival. As a result, "elderly people may have the most to gain from intensive cardiovascular risk management," the researchers concluded.
TIAs can easily be confused with other maladies, including migraine headaches. Digital news reporter and editor Kara Swisher, a healthy 48-year-old from San Francisco, initially suspected either migraine or jetlag when she began noticing odd sensations, such as tingling in her hands, on Oct. 18, a day after taking a 14-hour flight to Hong Kong. However, when she was talking to herself and the sounds "came out like gibberish," she went to a hospital where doctors diagnosed a TIA as well as a patent foramen ovale, a tiny hole in her heart present from birth. PFOs can produce migraines, TIAs and stroke. The Chinese doctors admitted her to the hospital and began giving her the blood thinner Lovenox (enoxaparin) to prevent a recurrence. Blood thinners are a TIA treatment mainstay.
The new findings, released Thursday in Stroke: Journal of the American Heart Association, came from the Program of Research Informing Stroke Management (PRISM) study. Gattellari's group analyzed cases of 22,157 Australian adults hospitalized with a TIA from July 1, 2000, to June 30, 2007, and followed them two to nine years. They linked the cases with death records through June 30, 2009, then compared the TIA patients' survival with expected survival for adults of the same sex and age.
Gattellari and her colleagues found that nearly 10 percent of patients hospitalized for a TIA died within a year (compared with 5 percent in the general population). By five years, more than 30 percent of TIA sufferers were dead (vs. 20 percent of the general population). By nine years, nearly half the TIA sufferers had died, their survival falling 20 percent below that of men and women without TIAs.
With each passing year after a TIA, the gap between patients' survival and expected survival widened. After one year, women fared a bit better than men, but by 5 years out, survival rates evened out for the sexes.
Findings Could Inform Follow-up Care, Preventing Another TIA
The researchers found that other diagnoses compounded TIA survivors' risk of dying. Congestive heart failure more than tripled it. Prior hospitalization for stroke more than doubled it, while a type of irregular heart rhythm called atrial fibrillation doubled it. High cholesterol didn't seem to pile on more risk after a TIA, suggesting that patients receiving that diagnosis were following heart-healthy recommendations to exercise more, stop smoking and eat healthfully, study authors said.
Gattellari and her co-authors said their findings were important because they revealed "the true impact of TIA on mortality" and could be used to inform decisions about follow-up care and strategies to prevent repeat TIAs.
"The most effective strategies are to set targets for cholesterol, blood pressure, exercise, weight, and diabetic control and smoking cessation, adjusting the medication over time to achieve target cholesterol and blood pressure levels," said study co-author Dr. John M. Worthington, a neurologist and associate professor at UNSW.
As the Hong Kong doctors did with Swisher, doctors usually administer anti-clotting drugs, such as aspirin, aspirin-like drugs or anticoagulants within hours of a TIA. "These drugs will usually continue for the life of the patient," Worthington said.
He cited "strong recent evidence that the more urgent and comprehensive the medical care, the better the outcome." Combining that care with lifestyle changes, "gives the patient the best chance for reducing their risk for all cardiovascular disease and risks," he said. "Our study emphasizes the importance of close, long-term management of risk factors after TIA."
"In a nutshell, TIA management is about urgent care, lifestyle changes, use of effective medications and close long-term follow-up," Gattellari told ABCNews.com.
Unfortunately, there still is no gold-standard method for diagnosing a TIA. Its transient nature means that brain imaging technologies like CT scans cannot detect it, so diagnosis relies predominantly on doctors' judgment. About a quarter of cases considered TIAs in the emergency room turn out, upon further investigation, to be strokes. About a quarter turn out to be some other disorder that mimics a TIA, the authors wrote.