Racial differences in platelet survival time in patients with symptomatic coronary atherosclerosis.

Abstract

Platelet survival times were studied in 40 patients (21 white and 19 black) with coronary artery disease and stable effort induced angina pectoris. The platelet survival times of 19 white controls (9.27 ± 0.49 days; mean ± SD) were not significantly different from those of 12 black controls (8.88 ± 0.81 days), and the platelet survival times for 21 white patients with coronary artery disease (8.46 ± 0.65 days) were lower than the times for both the white controls (p < 0.01) and the combined control group (p < 0.01). However, the difference between the mean platelet survival times of 19 black patients (9.22 ± 0.68) and the control groups was not significant, and the difference between the mean platelet survival times of the 21 white patients and the 19 black patients was significant (p < 0.01). Stepwise multiple linear regression analysis indicated that race was the most significant factor in predicting shortened platelet survival (r = 0.4783; p < 0.01). It is concluded that racial background should be considered in the interpretation of platelet studies and that reported racial differences in the rate and extent of atherosclerotic lesions may be related to racial differences in platelet consumption. (Arteriosclerosis 3:138-140, March/April 1983) T he platelet survival time has been reported to be shortened in 50% to 65% of patients with symptomatic coronary atherosclerosis. 1 " 4 We performed platelet survival studies as part of the initial evaluation of the effects of antiplatelet drugs in patients with stable effort angina pectoris and found fewer than one-third with shortened platelet survival times. This unexpected low incidence is explained by the finding that platelet survival times were decreased less often in our black than in our white patients. Methods Platelet Survival TestingOne unit of autologous platelets was collected, labelled with 150 to 200 ju.C of Na 2 51 CrO4, washed, and reinfused into the subject according to the method of Aster as modified by Harker.5 Blood samples were collected into disodium edatate anticoagulant daily for 7 to 9 days, and the platelets were extracted by differential centrifugation. Platelet radioactivity was measured in a well-type gamma counter, and a weighted platelet survival time was determined using a computer program based on a linear-exponential model of platelet disappearance. 6 Platelet survival times were studied in 31 control subjects. All were believed to be in good health and were taking no medication. Twelve controls were black (10 males; 2 females) and 19 were white (16 males; 2 females). Smoking history and serum cholesterol and triglyceride values were recorded.Forty outpatients volunteered for the study. All patients met the criteria of the New York Heart Association for stable effort angina pectoris. All had treadmill exercise tests which produced ischemic ST segment response, and coronary arteriograms which showed greater than 50% luminal diameter narrowing of one or more coronary arteries. No patients were taking drugs known to affect platelet funct...