Aspirin, Heparin, or Both to Treat Acute Unstable Angina

TLDR

In a double‑blind, randomized, placebo‑controlled trial of 479 patients with acute unstable angina, investigators compared aspirin 325 mg twice daily, heparin 1000 units/hour IV, and their combination, enrolling patients within an average of 7.9 h after symptom onset and following them for 6 ± 3 days until definitive therapy was chosen. The study found that heparin reduced refractory angina, all treatment arms lowered myocardial infarction rates (aspirin 3 %, heparin 0.8 %, combination 1.6 %) with no deaths, while the combination offered no additional benefit over heparin alone but increased serious bleeding (3.3 % vs. 1.7 %), leading to the conclusion that aspirin or heparin is preferable in the acute phase, with a trend favoring heparin.

Abstract

We tested the usefulness of aspirin (325 mg twice daily), heparin (1000 units per hour by intravenous infusion), and a combination of the two in the early management of acute unstable angina pectoris in a double-blind, randomized, placebo-controlled trial involving 479 patients. The patients entered the study as soon as possible after hospital admission (at a mean [±SD] of 7.9±8.0 hours after the last episode of pain), and the study was ended after 6±3 days, when definitive therapy had been selected. Major end points — refractory angina, myocardial infarction, and death — occurred in 23,12, and 1.7 percent of the 118 patients receiving placebo, respectively. Heparin was associated with a decrease in the occurrence of refractory angina (P = 0.002). The incidence of myocardial infarction was significantly reduced in the groups receiving aspirin (3 percent; P = 0.01), heparin (0.8 percent; P<0.001), and aspirin plus heparin (1.6 percent, P = 0.003), and no deaths occurred in these groups. There were too few deaths overall to permit evaluation of the effect of treatment on this end point. The combination of aspirin and heparin had no greater protective effect than heparin alone but was associated with slightly more serious bleeding (3.3 vs. 1.7 percent). We conclude that in the acute phase of unstable angina, either aspirin or heparin treatment is associated with a reduced incidence of myocardial infarction, and there is a trend favoring heparin over aspirin. Heparin treatment is also associated with a reduced incidence of refractory angina. (N Engl J Med 1988; 319:1105–11.)