THURSDAY, June 1, 2006 (HealthDay News) -- Even mildly impaired heart function -- a loss of blood-pumping ability so limited that it doesn't cause symptoms -- may increase the risk of stroke, a new study finds.
Cardiologists have known for some time that people with impaired function so severe that it's classified as heart failure are at increased risk of stroke, said Dr. Marco R. Di Tullio, professor of clinical medicine at Columbia University. But the study he wrote for the June issue of the journal Stroke seems to extend that risk to the much milder impairment called left ventricular dysfunction, or LVD.
The long-running study compared rates of left ventricular dysfunction in 270 New York City residents who suffered strokes and 288 stroke-free participants. All had undergone echocardiography, a test of heart function.
LVD was about five times more common in those who had strokes -- 24.1 percent of the stroke patients, compared to 4.9 percent of the stroke-free participants, the study found.
One important revelation was that the degree of heart dysfunction did not matter in terms of stroke risk. Any amount of LVD was associated with a three-fold increase in stroke incidence in men and an almost five-fold increase in women, Di Tullio said.
The findings should affect the way doctors assess the risk of stroke in their patients, he said.
"Normally, what physicians do is consider that people who have manifest heart failure have an increased risk," he said. "They don't think as much about the risk in people with mild dysfunction. But this is one of the factors that should be kept in mind in assessing the global risk of stroke."
But, Di Tullio added, it's not certain that the finding should influence treatment. There are some "preliminary indications" that drugs such as ACE inhibitors can delay the onset of heart failure in people with moderate dysfunction, but the evidence is not yet in to show that those people should get drug therapy, he said.
Dr. Peter Appelros, associate professor of neurology at Orebro University Hospital in Sweden, who wrote an accompanying editorial in the journal, agreed.
"I'm not ready to say that this has implications for treatment today, because we are awaiting studies that show that warfarin [a clot-preventing drug] has an effect in this situation," Appelros said.
Results of ongoing studies in Europe and the United States to determine whether anti-clotting therapy reduces stroke risk in such people should be available "later this year or next year," he said.
Di Tullio said an increased incidence of clot formation in people with left ventricular dysfunction is one possible explanation for the heightened risk of stroke. Another possibility is that LVD is associated with abnormal heartbeats, such as atrial fibrillation, that are known to increase the chance of stroke and other cardiovascular problems, he said.
The Columbia researchers are tracking a group of people who haven't had strokes to determine whether those with LVD have a higher incidence of stroke. "We will be able in a couple of years to see if what we have found is also confirmed by this long-term prospective study," Di Tullio said.
The American Heart Association describes the roster of risk factors for stroke.