Randomized Trial Comparing Intravenous Nitroglycerin and Heparin for Treatment of Unstable Angina Secondary to Restenosis After Coronary Artery Angioplasty

Abstract

Background —The treatment of unstable angina targets the specific pathophysiological thrombotic process at the site of the active culprit lesion. In unstable angina due to a restenotic lesion, smooth muscle cell proliferation and increased vasoreactivity may play a more important role than thrombus formation. Therefore, the relative benefits of nitroglycerin and heparin might differ in unstable angina associated with restenosis compared with classic unstable angina. Methods and Results —We randomized 200 patients hospitalized for unstable angina within 6 months after angioplasty (excluding those with intracoronary stents) to double-blind administration of intravenous nitroglycerin, heparin, their combination, or placebo for 63±30 hours. Recurrent angina occurred in 75% of patients in the placebo and heparin-alone groups, compared with 42.6% of patients in the nitroglycerin-alone group and 41.7% of patients in the nitroglycerin-plus-heparin group ( P <0.003). Refractory angina requiring angiography occurred in 22.9%, 29.2%, 4.3%, and 4.2% of patients, respectively ( P <0.002). The odds ratios for being event free were 0.24 (95% CI, −0.13 to 0.45, P =0.0001) for nitroglycerin versus no nitroglycerin and 0.98 (95% CI, −0.55 to 1.73, P =NS) for heparin versus no heparin. No patient died or suffered myocardial infarction. Conclusions —Intravenous nitroglycerin is highly effective in preventing adverse ischemic events (recurrent or refractory angina) in patients with unstable angina secondary to restenosis, whereas heparin has no effect.