Heparin-Releasable Endothelial Cell-Associated Tissue Factor Pathway Inhibitor (Tfpi) is Increased in the Coronary Circulation After Coronary Spasm in Patients with Coronary Spastic Angina

Abstract

Tissue factor pathway inhibitor (TFPI) is a physiological regulator of the extrinsic coagulation cascade. Coronary spasm can alter endothelial cell properties in the coronary artery with resultant thrombosis. To determine whether coronary spasm affects plasma TFPI level, we measured the heparin-releasable endothelial cell-associated TFPI (heparin-releasable TFPI) (ng/ml) in the coronary sinus and the aortic root before and after coronary spasm induced by an injection of acetylcholine in 18 patients with coronary spastic angina, and before and after myocardial ischemia induced by rapid atrial pacing in 18 patients with stable exertional angina, and in 17 control subjects with normal coronary arteries and no coronary spasm. Heparin-releasable TFPI level in the coronary spastic angina group significantly increased in the coronary sinus (122±46 to 147±63, p<0.001) after the ischemic event but not in the aortic root (113±44 to 121±58). The level in the coronary sinus and the aortic root remained unchanged after the ischemic event in the stable exertional angina group and after the injection of acetylcholine in the control group. The coronary sinus-arterial difference in the amount of the heparin-releasable TFPI significantly increased after the ischemic event only in the coronary spastic angina group (10±18 to 26 ±18, p<0.002). Our result suggested that heparin-releasable TFPI is increased in the coronary circulation after coronary spasm.