[Myocardial infarct of effort with normal coronaries. Study of in vivo platelet activation].
Platelet activation may play a part in causing myocardium infarction with angiographically normal coronary arteries. We investigated this possibility by performing ergometric stress testing in a series of 9 patients (Group A) who had suffered myocardial infarction after a violent effort with angiographically documented coronary insufficiency responsible for a stable effort angina (Group B) and 11 healthy subjects (Group C). Blood samples were taken separately before exercise, at the peak of exercise, and during the recovery period. Platelet morphology, a sensitive indication of the degree of platelet activation, was studied by phase contrast microscopy after immediate fixation of the blood. The percentage of non-discoidal platelets presenting with one or several spicules was measured. At the same time, the plasma concentrations of platelet factor 4 (PF4) and beta-thromboglobulin (beta-TG) were measured. At rest, there was no difference in platelet morphology or specific platelet proteins between the 3 groups. At the peak effort, there was a significant increase of the number of morphologically modified platelets in Groups A and B but not in healthy subjects. This platelet activation could not be linked to the presence of myocardial ischaemia because it was found both in patients with a negative maximal exercise stress test (Group A). Finally, no increase of the plasma concentrations of the platelet protein was observed in any of the groups.
D000328:Adult; D000368:Aged; D000787:Angina Pectoris / Q000097:blood*; D001792:Blood Platelets / Q000473:pathology*; D005080:Exercise Test; D006801:Humans; D008297:Male; D008858:Microscopy, Phase-Contrast; D008875:Middle Aged; D009203:Myocardial Infarction / Q000097:blood*; D005082:Physical Exertion; D010978:Platelet Factor 4 / Q000032:analysis; D001620:beta-Thromboglobulin / Q000032:analysis
D001620:beta-Thromboglobulin; D010978:Platelet Factor 4
Infarctus du myocarde d'effort à coronaires saines. Etude de l'activation plaquettaire in vivo.