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 measur ed plasma free-form TFPI antigen levels and monitored 24-h Holter reco rdings at 06.00, 14.00 and 22.00 h in 15 patients with coronary spasti c angina, 13 patients with stable exertional anginal and 11 control su bjects. There was a significant circadian variation in plasma free-for m 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 le vels at 06.00 h were significantly higher in coronary spastic angina p atients than in patients with stable exertional angina or control subj ects (p < 0.01). Free-form TFPI antigen levels increased after the isc hemic attacks in coronary spastic angina (p < 0.01), This circadian va riation correlated with the frequency of attacks, with the peak level occurring between midnight to early morning in patients with coronary spastic angina.