Circadian variation in plasma levels of free-form tissue factor pathway inhibitor antigen in patients with coronary spastic angina.

Tissue factor pathway inhibitor (TFPI) is known to inhibit the initial reaction in the tissue factor-mediated coagulation pathway. We measured plasma free-form TFPI antigen levels and monitored 24-h Holter recordings at 06.00, 14.00 and 22.00 h in 15 patients with coronary spastic angina, 13 patients with stable exertional angina, and 11 control subjects. There was a significant circadian variation in plasma free-form TFPI antigen levels in patients with coronary spastic angina (25.8+/-2.0 ng/ml at 06.00 h, 21.1+/-1.6 ng/ml at 14.00 h, and 20.2+/-1.4 ng/ml at 22.00 h; p<0.01). Furthermore, free-form TFPI antigen levels at 06.00 h were significantly higher in coronary spastic angina patients than in patients with stable exertional angina or control subjects (p<0.01). Free-form TFPI antigen levels increased after the ischemic attacks in coronary spastic angina (p<0.01). This circadian variation correlated with the frequency of attacks, with the peak level occurring between midnight to early morning in patients with coronary spastic angina.