Clot busters may put elderly people at risk. (Biomedicine).

Drugs that dissolve blood clots in heart attack patients save thousands of lives every year. However, a new study questions whether these powerful, so-called clot busters are safe for the oldest heart patients.

Researchers reviewed the medical histories of 2,659 heart attack patients admitted to 37 Minnesota hospitals during the 1990s. Of these, 735 received one of the main clot-busting drugs, such as streptokinase, shortly after their heart attacks. Researchers found that patients over age 80 getting the drugs were significantly more likely to die during their hospital stay than were patients of similar age who didn't get the clot busters, says study coauthor Stephen B. Soumerai of Harvard Medical School in Boston. The work appears in the March 12 Archives of Internal Medicine.

Patients younger than 75 who don't have contraindications to clot busters, such as very high blood pressure or a history of bleeding, are likely to benefit from the drags, Soumerai says. However, this study suggests that older people have underlying characteristics--such as fragile blood vessels--that make the clot-dissolving drugs a risky option, he says.

The gold standard for resolving such questions in medicine is the randomized, double-blind, controlled trial, in which one group of patients gets a drug and a similar group gets a placebo. Not until the end of the study do physicians and patients learn who was getting the real thing. Clot busters have already passed such tests, but those trials included many heart attack victims in their 50s and 60s, Soumerai says. In light of the new results, the researchers suggest that physicians use greater caution in prescribing the drugs, particularly to their elderly patients. --N. S.