Failure of adjuvant heparin to reduce myocardial ischemia in the early treatment of patients with unstable angina

Angina pectoris is chest pain that results from myocardial ischemia, or the temporary reduction in cardiac blood flow. Unstable angina is a rapidly deteriorating type of angina, caused in part by the formation of intracoronary thrombi (blood clots in the coronary arteries), that often presages the onset of more a more severe cardiovascular emergency such as heart attack. The long-term (for periods greater than six days) use of anticlotting drugs, such as heparin, is well established as a therapeutic strategy for the treatment of unstable angina. With current economic pressures to reduce the duration of hospital stays, it is of interest to know whether there is any therapeutic advantage to be gained by short-term intravenous administration of heparin. (The intravenous route of administration requires hospital care.) To determine the effect of short-term heparin administration on the frequency of ischemic events, a study was carried out involving 47 patients being treated for unstable angina. Twenty patients received intravenous heparin in addition to their other medications for the first 36 hours of evaluation; the remainder received an inactive saline (salt) solution in addition to the medications they had been taking. In both groups these medications included calcium channel blockers, beta adrenergic blocking agents, nitrates, and aspirin. Myocardial ischemia was monitored by electrophysiological monitoring of cardiac function. There was no difference in the frequency of ischemic events between the groups receiving heparin and saline. About 40 percent of both groups suffered ischemic episodes, the majority of which (85 percent) were asymptomatic. The failure of heparin to reduce the incidence of ischemia may be attributable to a masking effect of aspirin (which has much the same effect), the length of treatment, or the possibility that heparin might not exert its effects on angina solely by reducing myocardial ischemia. (Consumer Summary produced by Reliance Medical Information, Inc.)