Clot-Busting Drugs: the Sooner the Better
Not only does starting treatment within an hour of a heart attack improve survival rates, but administering a clot-dissolving drug before a patient reaches the hospital also appears to increase the chances of recovery.
In a study of 315 heart attack patients in 20 areas where ambulance crews can administer such drugs, researchers found that patients got the first of two doses of the drug Retavase within 31 minutes of the crews’ arrival. That compared with the average 63-minute wait for patients treated after admission to the same hospitals in the previous year. (The second dose always is given 30 minutes after the first.)
“Beginning drug treatment of heart attack patients as soon as possible--even before they reach the hospital--is an important goal because the longer a patient waits to receive treatment, the greater the extent of permanent damage,” said Dr. David Morrow, a cardiologist at Brigham and Women’s Hospital in Boston. He was lead investigator of the study that appeared in the July 3 issue of the Journal of the American College of Cardiology.
The patients’ electrocardiograms provided evidence that early treatment was making a difference. A heart attack creates characteristic changes in certain patterns on the electrocardiogram, or ECG.
Researchers found that 26% of the heart attack patients treated by ambulance crews had a 50% improvement in a key part of their ECG by the time they reached the emergency room. In addition, 14% of the patients treated early showed what’s considered a complete resolution (a better than 70% improvement) in that ECG irregularity before reaching the emergency room. Nearly half the patients had complete resolution of the irregularity within 90 minutes of their first Retavase dose. Among the entire group studied, doctors reported 14 deaths (4.7% of the patients) and three cases of bleeding into the brain (1% of the patients).
Retavase, or reteplase, is the most widely prescribed among the clot-dissolving drugs that restore blood flow to a damaged part of the heart by targeting the fibrin protein in clots. Use of Retavase before hospital arrival was tested in 15 states that allow ambulance crews to administer clot-busting drugs; California isn’t among them.
