Avoidance of a Reload During the Therapeutic Shift From Clopidogrel to Ticagrelor in Patients With Acs Has No Influence on Residual Platelet Reactivity

Background: Ticagrelor (TICA) was more efficient than clopidogrel (CLO) in preventing cardiovascular events after Acute Coronary Syndrome (ACS) in the PLATO trial. However, it was associated with a higher incidence of non-procedure related bleedings. Despite TICA therapy was always started with the administration of a loading dose in the PLATO trial, the loading dose could be unnecessary in patients with ongoing CLO therapy. Aim of the present study was to verify whether the administration of a loading dose is necessary to mantain the level of inhibition of aggregation during the switch from ongoing CLO to TICA therapy. Methods and Results: Fifty patients with ACS and on CLO treatment were randomly assigned to a starting dose of TICA of 90mg (Group 1) or 180mg (Group 2), on top of aspirin treatment. Platelet aggregation was measured using multiple electrode aggregometry (MEA) at 0, 2, 6, 24 and 72h after the switch, and verified through standard LTA aggregometry. No relevant difference in platelet aggregation between the two study arms was observed at baseline (p=0.256). Residual platelet aggregation measured using MEA was significantly reduced in both arms 2h after the first administration of TICA (both p<0.001). Interestingly, no difference in aggregation was found 2 hours after the switch to TICA (176 72 vs 181 60 AUmin, p=0.281). Similar findings were confirmed with LTA. Conclusions: Therapeutic switch from ongoing clopidogrel therapy to ticagrelor without administration of a loading dose is clinically safe and is not associated to a lower degree of inhibition in patients with ACS. Avoiding the loading dose could be associated to a lower bleeding risk while mantaining the same level of aggregation. Larger trials are needed to confirm data from our proof-of-concept study.