EXCRETION OF THROMBOXANE A2 AND PROSTACYCLIN METABOLITES BEFORE AND AFTER EXERCISE TESTING IN PATIENTS WITH AND WITHOUT SIGNS OF ISCHEMIC-HEART-DISEASE

We addressed the hypothesis that platelets are not activated in association with effort-induced myocardial ischemia in stable coronary disease. Seventy-two patients undergoing a diagnostic bicycle exercise test were stratified according to the development of chest pain (yes/no, 33/39) and of exercise-induced ST-segment depression of at least 200 μV in the electrocardiogram (yes/no, 12/60). Noninvasive indexes of platelet activation and of platelet/vessel wall interaction (urinary excretion of the 2,3-dinor-metabolites of thromboxane A2 [Tx-M] and prostacyclin [PGI-M], respectively) were analyzed in samples collected in the basal state and after the test. Basal Tx-M and PGI-M did not differ in patients with (236±35 and 131±22 pg/mg creatinine, respectively) and without (185±16 and 101±13 pg/mg creatinine, respectively) chest pain, or in those with (178±45 and 162±41 pg/mg, respectively) and without (216±22 and 104±11 pg/mg, respectively) ST-segment depression during the test. Patients without chest pain or without ST-segment depression moderately increased (p<0.05) their urinary Tx-M (by 21% and 13%, respectively) and PGI-M (by 28% and 23%, respectively) after exercise. No significant increases were observed in those developing chest pain or ST depression during exercise. These data indicate that effort-induced myocardial ischemia is not associated with an increase in platelet activation or platelet/vessel wall interaction in patients with stable coronary disease.