Effects of the platelet inhibitor ticlopidine on exercise tolerance in stable angina pectoris

Coronary blood flow might be reduced by platelet aggregatesor by vasospasm induced by platelet-produced thromboxane A2.Therefore the effects of the platelet inhibitor ticlopidine(500 mg daily) on platelet function and on exercise tolerancewere investigated in a double-blind placebo-controlled studyin 38 middle-aged men with stable incapacitating angina pectoris.Before and after 4 and 8 weeks of treatment, exercise testswere performed in warm and cold environments. The in vitro plateletreactivity to ADP was determined at rest and the plasma levelsof beta-thromboglobulin (BTG) and platelet factor 4 (PF4) weremeasured before and immediately after exercise. There were nosigns of increased platelet activity at rest or after exerciseas judged by the levels of BTG and PF4. Despite a potent inhibitionof platelet reactivity to ADP in vitro during ticlopidine treatment,the exercise tolerance was reduced in exercise tests in bothwarm and cold environments and in daily life. Therefore plateletactivity does not seem to play any significant role in exercisetolerance in the stable phase of angina pectoris.