Effect of amlodipine on exercise-induced platelet activation in patients affected by chronic stable angina

Background: Literature concerning exercise-induced platelet activation in c hronic stable angina is somewhat confusing. The reason lies in the type of exercise as well as in methodological problems. A powerful, recently introd uced procedure to detect platelet activation is flow cytometry. Platelet re sponse to activating factors is mediated by calcium uptake; however, calciu m antagonist effect on platelet activity is still unclear. Hypothesis: The study was undertaken to investigate exercise-induced platel et activation before and after treatment with amlodipine in chronic stable angina. Methods: Twenty patients with chronic stable angina were entered into the s tudy. Each subject underwent a symptom-limited cycloergometer stress test f ollowing a washout period of 2 weeks. Blood samples were collected before a nd immediately after exercise. All subjects were then randomized into two g roups of 10 patients each, with Group 1 and Group 2 taking amlodipine 10 mg /day, and placebo for 4 weeks, respectively. They subsequently underwent a second exercise stress test, and blood samples were obtained before and imm ediately after exercise. Flow-cytometric evaluation of platelet activity wa s performed in order to recognize GMP-140 expression on platelet membrane. Results: Strenuous exercise induced a significant increase in platelet acti vation in all subjects prior to therapy. No significant differences were ob served in platelet activity at rest between Groups 1 and 2, whereas a signi ficant decrease in exercise-induced platelet activation was demonstrated in Group 1 compared with Group 2. Conclusion: Our data provide evidence of the favorable effect of amlodipine on exercise-induced platelet activation in patients affected by chronic st able angina.