The present study has been designed to investigate protein C (as protein C antigen) and fibrinopeptide A (FpA) concentration in plasma from patients suffering from ischemic heart disease in relation to the frequency of ischemic attacks , in order to estabilish if modifications in protein C levels could contribute to blood clotting activation. Protein C and FpA levels in plasma were measured in 30 controls and in two groups of patients with angina. The first group was formed by 27 patients

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... ing from spontaneous ischemic attacks (active angina). The second one was formed by patients who previuosly suffered from angina, but were free from myocardial ischemic attacks for at least one month (inactive angina). Protein C (measured by electroimmunoassay) was higher in the whole group of patients than in controls (122.1+ 20.2 vs. 96.5+±14 p<0.001)? Moreover significantly higher values were found in patients with active angina in comparison to patients with inactive disease (132.5+±15.7 vs 112.3+±17.6,p<0.001).Similarly patients suffering from active angina had FpA levels higher than patients with inactive angina (8.6+±9.4 vs 5.5+±7.0,p<0.01) or controls (1.6+±1.0,p<0.001). A high concordance (76%) between protein C and FpA levels exceeding normal limits was found in patients with active angina (p < 0.05) but no statistically significant correlation existed between protein C and FpA levels and between protein C or FpA levels and coronary pathoanatomy. These results confirm a significant involvement of blood clotting system in ischemic heart disease and especially in active angina.