[Thrombin-antithrombin III complexes as a measure of effective heparin treatment?]

To study the effect of heparin on thrombin formation in vivo, we measured thrombin-antithrombin III complexes (TAT) in 26 patients treated with heparin for acute coronary artery disease or deep vein thrombosis. There was a statistically significant correlation between activated partial thromboplastin time and heparin concentration, but none was found between these tests and TAT. Abnormal TAT values in 45% of the patients showed that therapeutic heparin concentration did not inhibit thrombin formation in vivo, or did so only partially.