Platelet-release reaction in myocardial infarction.

A study was made of the platelet-release reaction in heparinised platelet-rich plasma taken from 26 patients, of whom 22 had sustained a definite and four a possible myocardial infarction, and from 54 age-matched controls. No significant differences in reaction were observed between the two groups. Signficant differences were seen, however, between eight patients who died within a year after infarction and the controls (P less than 0.01) and the remaining 18 patients who survived (P = 0.02). These differences were abolished when sodium citrate was included in the experimental procedure. Poor prognosis was thus related to an increased platelet-release reaction after infarction.