Platelet Factor 3 Activity and Platelet Aggregation in Patients Submitted to Coronarography

37 patients submitted to coronarography were compared to 19 controls having no risk factors for coronary heart disease. It was solely in the patients having the most severe lesions that the cholesterol and triglycerides in plasma, and the susceptibility of platelets to thrombin induced aggregation were significantly higher than in the controls. By contrast, all the patients including those in whom significant lesion could not be shown by the arteriography, presented a highly significant increase in the activity of platelet factor 3 activity related in most of the patients, to an in vitro hyper‐coagulability. This enhanced platelet factor 3 activity appears to be related to an increase in the clotting activity of the platelet phospholipids.