Effects of trimetazidine on in vivo coronary arterial platelet thrombosis.

We used Folts' model of critical coronary artery stenosis with endothelial damage, which measures platelet-rich thrombus accumulation from cyclic flow reductions (CFRs). This paper reports results applied to trimetazidine, a member of the piperazine group. Trimetazidine at a dose of 1 mg/kg completely abolished CFRs caused by accumulating thrombus in the circumflex coronary artery in 4 of 8 open-chest anesthetized beagles. More trimetazidine (up to 5 mg/kg) abolished CFRs in two more and attenuated them in the remaining two dogs. There were no systemic hemodynamic effects observed. Adrenaline was then infused to stimulate platelet activation. At a rate of 0.4 microgram/kg/min, CFRs were restored in one dog only. Adrenaline given at 1.6 micrograms/kg/min resulted in restoration or increase in the slope of CFRs in all animals. A further six nonoperated dogs were anesthetized and given trimetazidine 3 mg/kg. Routine coagulation studies were not altered. However, aspirin 5 mg/kg significantly increased bleeding time, whereas trimetazidine alone did not. These findings suggest that trimetazidine is effective in preventing intracoronary platelet aggregation in this model. Because of its demonstrated sparing of coagulation factors and its lack of effect on bleeding time, the cause is unlikely to be inhibition of the fibrinogen or thrombin receptors, or interference with arachidonic acid metabolism.