Increased plasma concentrations of platelet factor 4 in coronary artery disease: a measure of in vivo platelet activation and secretion.

Previous studies have shown that there is both a significant shortening in platelet survival and a measured hyperactivity to platelet-aggregating agents in patients with documented coronary artery disease compared with control groups. We used a recently described radioimmunoassay for the platelet-secreted protein platelet factor 4 (PF4) to study 162 patients with documented coronary artery disease. There was a significant increase in plasma PF4 concentrations in patients with documented coronary artery disease compared with angiographically normal patients (8.7 vs 16 ng/ml, respectively, n = 121), but as in previous studies of platelet survival, we could not correlate elevated plasma PF4 concentration and the severity or site of the coronary artery disease. In addition, there was no correlation with left ventricular function, serum cholesterol or the type of angina. Patients with confirmed acute myocardial infarction had no significant difference in mean plasma PF4 concentrations compared with similar groups of coronary disease patients who had prolonged chest pain or chronic stable angina. Coronary artery bypass grafting in a subgroup of patients did not affect the mean plasma PF4 concentration during 1 year of follow-up after bypass surgery, but medical therapy for angina with increasing doses of propranolol and nitrates significantly reduced PF4 concentration in another subgroup of patients who were not considered to be candidates for surgical therapy.