Platelet release in coronary heart disease: effect of antiplatelet drugs and coronary artery bypass graft.

We report serial measurements of in vivo platelet release products beta-thromboglobulin and platelet factor 4 in 38 patients with coronary artery disease who underwent coronary artery bypass graft surgery. All patients were given dipyridamole preoperatively and both dipyridamole and aspirin postoperatively. Assays of plasma beta-thromboglobulin and platelet factor 4 were performed immediately before surgery, at discharge, and at follow-up visits. At initial evaluation, 22 patients with prior myocardial infarction had significantly elevated plasma beta-thromboglobulin levels (p = 0.0004). In the preoperative period, the use of dipyridamole caused some reduction of plasma beta-thromboglobulin and platelet factor 4, but the difference was not statistically significant. Six to 12 days after surgery, all patients had plasma beta-thromboglobulin concentrations higher than the preoperative levels despite the continued ingestion of dipyridamole and aspirin. At a follow-up visit, 30 to 133 days after surgery, only patients with previous myocardial infarction had beta-thromboglobulin levels higher than their preoperative values. However, compared with controls, all patients who underwent coronary artery bypass graft surgery had elevated plasma levels of beta-thromboglobulin in both the early and late postoperative periods. In this group of patients, successful revascularization of the myocardium, as indicated by relief of symptoms, did not completely inhibit platelet activation.