Short-term effect of exercise on platelet factor 4 in normal subjects and in patients with coronary artery disease

The aim of this study was to evaluate the plasma concentration of a platelet-derived protein, platelet factor 4 (PF4), before and after exercise in coronary artery disease.

We enrolled 60 patients with documented ischemic heart disease. The subjects were divided into two groups: Group 1 patients with previous myocardial infarction (n = 20, 13 males, 7 females, mean age 51.6 +/- 7.5 years, range 38-62 years); Group 2 patients with exercise-induced angina (n = 40, 22 males, 18 females, mean age 52.6 +/- 8.0 years, range 38-65 years). Patients with hypertension, hyperlipidemia and diabetes were excluded. Patients with angina or ST segment depression during the stress test were included in a subgroup (n = 33, 21 males, 12 females, mean age 50.3 +/- 6.3 years, range 40-65 years). Twenty healthy subjects without coronary risk factors (13 males, 7 females, mean age 53.2 +/- 7.1 years, range 38-65 years) served as controls. PF4 was measured in all patients at baseline and 5 min after a bicycle exercise test. Plasma PF4 levels were measured performed by radioimmunoassay (ng/ml, normal range 0-10).

Patients with ischemic heart disease showed a high basal concentration of PF4 compared with controls. PF4 levels at baseline vs after stress test were 4.1 +/- 2.5 vs 5.3 +/- 2.6 ng/ml in healthy subjects; 33.4 +/- 15.8 vs 56.2 +/- 28.2 ng/ml (p < 0.001) in Group 1; 22.4 +/- 15.8 vs 44.6 +/- 28.4 ng/ml (p < 0.001) in Group 2; 29.9 +/- 15.5 vs 67.7 +/- 26.1 ng/ml in the subgroup with angina or ST segment depression (p < 0.001), and 23.1 +/- 16.5 vs 26.0 +/- 18.1 ng/ml in those without angina or ST segment depression (NS).

These findings support the hypothesis that a significant increase in PF4 levels after exercise is associated with clinically significant coronary artery disease.