Aspirin inhibits the early myocardial release of thromboxane B2 and ventricular ectopic activity following acute coronary artery occlusion in dogs.

Acute coronary artery occlusion in anaesthetized open-chest greyhounds led to early release of thromboxane B2 (TxB2) into venous blood draining the ischaemic region. No release occurred from the remainder of the left ventricular wall (coronary sinus sampling). TxB2 release and ventricular ectopic activity were positively correlated (r = 0.863) 2 min post-occlusion. Aspirin (3 mg/kg i.v.) suppressed both local TxB2 release and ectopic activity and prevented ventricular fibrillation. It is suggested that TxB2 release is a factor contributing to early post-infarction arrhythmias.