Contrary to general belief among doctors, clot-busting drugs--the main emergency treatment for heart attack victims--fail to benefit patients more than 75 years old and may actually increase their risk of death, according to results of a Johns Hopkins-led study.
Older heart attack patients who received intravenous thrombolytics, medications that dissolve clots in the blood vessels supplying the heart, were nearly 40 percent more likely to die within 30 days of treatment than their counterparts not given the medications, according to the study. Results are published in the May 16 issue of Circulation, an American Heart Association journal.
"There has been a widespread belief that clot-busting drugs help older patients just as they do younger ones, but the evidence always has been equivocal and the question had never been directly tested until now," says David R. Thiemann, lead author of the study and assistant professor of medicine at Hopkins. "We found that in actual clinical practice the effectiveness of these drugs varies markedly with age. Younger patients clearly benefit from thrombolytics, but the one-third of heart attack patients who are older than 75 are unlikely to have any benefit and may be at higher risk of death. More studies on how to treat the older population are urgently needed."
The study used data from the Cooperative Cardiovascular Project (conducted by the Health Care Financing Administration) on 7,864 Medicare patients aged 65 to 86, who arrived at hospitals with an acute heart attack and who were candidates for clot-dissolving therapy. There were 5,191 patients aged 65 to 75 and 2,673 patients aged 76 to 86.
Patients aged 65 to 75 who received thrombolytic therapy had a 30-day death rate of 6.8 percent, compared with 9.8 percent for patients who did not get the medications. Among patients aged 76 to 86 years, the pattern was reversed: The death rate for patients treated with thrombolytics was 18 percent, compared with 15.4 percent for patients who did not get the medications.
Thiemann says there are several possible reasons for differences between the new findings and the conventional wisdom, which was based on research trials of clot-busting drugs conducted about a decade ago.
"Patients in general clinical practice are older and sicker than the selected patients enrolled in research trials, so deaths from major side effects such as stroke, bleeding and cardiac rupture may be more common," he says. "In addition, hospitals do not always adhere to the rigorous protocols that govern research trials, so the results in actual nationwide practice may be different."
The study was supported by the Delmarva Foundation for Medical Care, Easton, Md; the Health Care Financing Administration; and the Harry and Jeanette Weinberg Foundation of Baltimore.
Other authors were Josef Coresh, Steven P. Schulman, Gary Gerstenblith and Neil R. Powe, of Hopkins; and William J. Oetgen, of the Delmarva Foundation for Medical Care.