BackgroundPatients with unstable angina despite intensive medical therapy, ie, refractory angina, are at high risk for developing thrombotic complications: myocardial infarction or coronary occlusion during percutaneous transluminal coronary angioplasty (PTCA). Chimeric 7E3 (c7E3) Fab is an antibody fragment that blocks the platelet glycoprotein (GP) Ib/IIIa receptor and potently inhibits platelet aggregation.Methods and ResultsTo evaluate whether potent platelet inhibition could reduce these complications, 60 patients with dynamic ST-T changes and recurrent pain despite intensive medical therapy were randomized toc7E3 Fab or placebo. After initial angiography had demonstrated a culprit lesion suitable for PTCA, placebo orc7E3 Fab was administered as 0.25 mg/kg bolus injection followed by 10 μg/min for 18 to 24 hours until 1 hour after completion of second angiography and PTCA. During study drug infusion, ischemia occurred in 9c7E3 Fab and 16 placebo patients (P= .06). During hospital stay, 12 major events occurred in 7 placebo patients (23%), including 1 death, 4 infarcts, and 7 urgent interventions. In thec7E3 Fab group, only 1 event (an infarct) occurred (3%,P= .03). Angiography showed improved TIMI flow in 4 placebo and 6c7E3 Fab patients and worsening of flow in 3 placebo patients but in none of thec7E3 Fab patients. Quantitative analysis showed significant improvement of the lesion in the patients treated with c7E3 Fab, which was not observed in the placebo group, although the difference between the two treatment groups was not significant. Measurement of platelet function and bleeding time demonstrated >90% blockade of GPIIb/IIIa receptors, >90% reduction of ex vivo platelet aggregation to ADP, and a significantly prolonged bleeding time during c7E3 Fab infusion, without excess bleeding.ConclusionsCombined therapy withc7E3 Fab, heparin, and aspirin appears safe. These pilot study results support the concept that effective blockade of the platelet GPIIb/IIIa receptors can reduce myocardial infarction and facilitate PTCA in patients with refractory unstable angina.