The role of exercise on platelet aggregation in patients with stable coronary artery disease: Exercise induces aspirin resistant platelet activation

Objectives: The aim of our study was to determine the relation between exercise stress test and aspirin resistance in patients with stable coronary artery disease. Background: Clinically aspirin resistance is defined as having thrombotic and embolic cardiovascular events despite regular aspirin therapy. Methods: We studied platelet functions of 62 patients with stable coronary artery disease and 20 subjects with normal coronary arteries by Platelet Function Analyzer (PFA-100, Dade Behring, Germany) at rest and after exertion with collagen and/or epinephrine (Col/Epi) and collagen and/or ADP cartridges. Closure time (CT) < 186 seconds was defined as aspirin resistance with Col/Epi cartridges of PFA-100. Symptom limited treadmill stress test (protocol of Bruce) was performed with Oxford Streslink TD-1 system. Results: 8 (12.9%) patients were aspirin resistant by PFA-100 (CT < 186s despite regular aspirin therapy) at rest. At the first minute of the recovery period of exercise stress test 14 (22.5%) patients were aspirin resistant by PFA-100. CTs with Col/ADP were respectively 89 +/- 6 s (83-100s) and 89 +/- 5 s (82-104s) at rest and after exercise (p = 0.107). 20.3% (11/54) of patients known as in vitro aspirin sensitives at rest had shorter CTs and 11.1% (6/54) had aspirin resistance after exercise (p = 0.004). There was no statistically significiant difference in platelet functions in the control group after exertion. Conclusion: We conclude that 11.1% of in vitro aspirin sensitive subjects at rest had aspirin resistance after exercise by PFA-100. In some individuals, exercise induced platelet activation is aspirin insensitive at usual antiplatelet doses. We need further clinical trials to optimize antiplatelet therapy in patients with coronary artery disease.