Serum antithrombin in coronary-artery disease.

Serum antithrombin activity (AA) was correlated with coronary angiographic findings in 69 patients with documented angina. There was excellent correlation between normal values and normal coronary circulation or only one-vessel stenosis in 30 of 35 patients (86%). When AA was above 90%, 90% of patients (20 of 22) had normal circulation or one-vessel occlusion. In 24 patients AA values were significantly decreased. Coronary angiography in this group revealed three with normal circulation or only one-vessel involvement (10%); 21 of 24 had two or three vessels occluded (90%). The correlation between severe CAD and low AA is probably coincidental to a "triggered" or "turned-on" clotting system. The most practical clinical contribution of AA estimation relates to this capacity to identify angina patients in whom clot-preventive measures (aspirin; dipyridamole; anticoagulants) might prove beneficial.