Production of circulating platelet aggregates by exercise in coronary patients.

To determine the effect of exercise on the in vivo formation of circulating platelet aggregates in patients with severe coronary artery disease (CAD), platelet aggregate ratios (PAR) (normal 0.8-1.1)were measured immediately before and after treadmill exercise and 30 minutes after exercise in 17 CAD patients (group 1, mean age 55 years), 12 age-matched normal subjects (group 2), and 13 young normals (mean age 27 years, group 3).Coronary patients had lower resting PAR than group 3 (0.79 ± 0.05 vs 0.98 ± 0.03; p < 0.01), while group 2 had an intermediate value 0.86 4-0.04 (p > 0.05 vs CAD and group 3).Immediately after exercise, group I PAR declined from 0.79 i 0.05 to 0.53 ± 0.04 (p < 0.001), while groups 2 and 3 were un- changed (p > 0.05; both p < 0.001 vs group 1); 30 minutes after exercise, PAR in group 1 rose to 0.66 ± 0.05 (p < 0.05 vs pre-and immediately postexercise); groups 2 and 3 remained unchanged vs pre-and immediately postexercise (p > 0.05; both p < 0.001 vs group 1).Six group 1 patients received 1300 mg aspirin daily for 10 days and repeated the protocol.Resting PARs were unchanged (p > 0.05) from resting values without aspirin.The exercise-induced decline in PAR was attenuated by aspirin: without aspirin, 0.73 ± 0.02 preexercise to 0.54 ± 0.04 postexercise; with aspirin, 0.73 ± 0.03 to 0.82 ± 0.03 (p < 0.05 vs no aspirin).These data indicate that platelet aggregation occurs with exercise in CAD.In addition, these data suggest that aspirin exerts a significant inhibitory effect on exercise-induced platelet aggregation in CAD patients.