The results look good, an American expert says, but more information is needed before basic changes are made in heart attack treatment.
Patients are routinely given aspirin in the hours after a heart attack because it prevents the blood cells called platelets from clumping together to form clots that reduce blood flow. However, a study done at seven clinics in the Netherlands finds improved blood flow and better survival in selected patients who also got warfarin, which acts in a different way to prevent clotting. The report appears in tomorrow's issue of Circulation.Those patients had a distinctive pattern called ST-elevation on their electrocardiograms, an indicator often associated with blood clot formation. After three months, a new examination showed that arteries remained open in 85 percent of the patients who got the aspirin-warfarin combination, compared to 72 percent of those who got aspirin alone.
Problem-free survival was significantly better for those who got the combined treatment -- 86 percent versus 66 percent for the aspirin-only patients. Only 2 percent of those who got both drugs had second heart attacks, compared to 8 percent of those got only aspirin.
"People have only thought about platelets in blocked arteries," says Dr. Freek W. A. Verheugt, lead author of the report and director of cardiology at the Heartcenter of University Medical Center in Nijmegen, Netherlands. "We also think about anticoagulant proteins in the blood. They are a threat for recurrent blockage. It has been thought that aspirin would do the trick, but it is not enough. This will change the way we protect our post-infarct [heart attack] patients."
However, Dr. Richard C. Becker, a professor of medicine at the University of Massachusetts Medical School and a spokesman for the American Heart Association, has a more cautious appraisal.
"For us in the United States, we would have to see the results of larger-scale trials before any changes across the board could recommended," Becker says. "Warfarin needs careful monitoring, and carries the risk of bleeding. We would need more information before we would change treatment."
Research that appeared in The New England Journal of Medicine last November voiced the same concern over using warfarin after strokes to prevent clotting. It found aspirin was just as good as warfarin at preventing second strokes, and it didn't carry the same potential dangers.
The seven-year study included more than 2,200 people who had had strokes because of blockages in arteries leading to their brains. The researchers noted warfarin has the potential to cause dangerous bleeding, and people using it must take blood tests every three or four weeks to avoid problems.
Warfarin, also known as coumarin, is associated with a higher risk of dangerous bleeding, Verheugt acknowledges. However, in the latest trial, the incidence of excess bleeding in patients who got the anticoagulant was not significantly higher than in those who got just aspirin, he says.
Also, European cardiologists are conducting studies to see whether a newer and hopefully less risky anticoagulant, melagratin, could be used instead of warfarin, Verheugt says. Melagratin is not approved for general use in Europe or the United States.
Those studies are among a number being done to see how current treatment in the critical hours after a heart attack can be improved, Becker says. Until results of those studies can be evaluated, "aspirin is clearly part of the standard of care," he says. The Dutch study "is important, no question about it, but we need to see the results of the ongoing studies before we can make any recommendations."
The trial is important because it "emphasizes the need for early diagnosis and treatment for heart attacks," Becker says. "It also underscores the importance of having treatment strategies available to prevent re-blockage."
What To Do
To get quick, lifesaving treatment, you need to recognize the symptoms of a heart attack, and you can learn them from the American Heart Association. To learn more about anticoagulant drugs, click here.