Plasma concentrations of platelet factor 4 in acute myocardial infarction.

The aim was to investigate whether in the acute stage of myocardial infarction (MI) platelet activation, as measured by plasma platelet factor 4 (PF-4), excluding that in ischaemic heart disease (IHD) is taking place. Over a period of 4 d the plasma levels of PF-4 were determined on 44 consecutive patients admitted to a coronary care unit with suspected MI. 21 of them had a definite acute MI (group 1), and 13 had evidence of IHD but no MI (group 2). In the remaining 10 subjects there was no evidence of either MI or IHD. On the first day the mean plasma PF-4 concentrations in group 1 and 2 patients were 11,8 +/- 1.1 and 15.0 +/- 2.3 ng/ml, respectively; the difference between means was not statistically significant. A peak mean PF-4 for group 1 patients (17.5 +/- 4.6 ng/ml) was recorded on the second day of study. The corresponding value for group 2 patients was lower, but not significantly so. In the latter subjects no peak PF-4 was recorded. During the last 2 d of study the plasma PF-4 concentrations tended to decrease, but the means for the 2 groups did not differ statistically. Thus, at no point in time was there a significant difference between the PF-4 values for MI and IHD patients present.