LACK OF ANY ADDITIONAL BENEFIT IN COMBINING ASPIRIN WITH ILOPROST IN A CANINE MODEL OF MYOCARDIAL REPERFUSION INJURY

The effects of iloprost infusion (100ng/kg/min for 75 min) alone and i n combination with aspirin (3mg/kg IV bolus) were compared in a canine model of myocardial reperfusion injury. Regional ischemia of 40 min w as produced by temporary occlusion of the left anterior descending cor onary artery, after which the myocardium was reperfused for a period o f 3 hours. Mean arterial pressure (MAP), heart rate (HR), left ventric ular end diastolic pressure (LVEDP), positive (+) LVdP/dt(max) and neg ative (-) LVdP/dt(max) were monitored. Rate pressure product and (-) d P/dt/P-max were also derived from the above. Myocardial tissue levels of adenosine triphosphate (ATP), creatine phosphate (CP), glycogen and lactate were estimated. Following reperfusion in the saline treated g roup, there was a significant fall in (i) MAP, (ii) (+) LVdP/dt(max) a nd (iii) (-) LVdP/dt(max). LVEDP was corrected about 2 hours after rep erfusion. Despite correction of lactate accumulation, ATP and glycogen were not restored although the CP store was replenished. The hemodyna mic profiles in both iloprost and in combination treated groups were s imilar; (i) depressed MAP (particularly during iloprost infusion) with out any significant change in HR (ii) no significant depression in (+) LVdP/dt(max) (iii) depression in (-) LVdP/dt(max) but not when correc ted for lower P-max and (iv) a significant reduction in the incidence of reperfusion arrhythmias. Similarly, in both the drug/s treated grou ps, ATP, CP and lactate were normalised although glycogen store was no t restored. The results of this study indicate (i) cardioprotective ef fect of iloprost even when administered prior to reperfusion and (ii) no additional protective effect of combining iloprost and aspirin.