Standard (180mg) vs high (360mg) loading dose of ticagrelor in patients with STEMI undergoing primary PCI

Abstract

Purpose: In ST elevation myocardial infarction (STEMI) patients a suboptimal degree of platelet inhibition for the first 2 hours has been described following the standard (180 mg) ticagrelor loading dose (LD). We aimed to compare the pharmacodynamic effect of double (360mg) vs standard LD of ticagrelor in STEMI patients undergoing primary percutaneous coronary intervention (PCI). Methods: We performed a prospective, non-randomized, 2-center study in 42 consecutive, P2Y12 inhibitor naive STEMI patients. Following blood sampling (Hour 0), patients were administered a 360 mg of ticagrelor, immediately before PCI. Platelet reactivity (PR) was assessed at Hour 0, 0.5, 1, 2 and 4 with the VerifyNow assay. PR was assessed at the same time-points in a control group of 32 STEMI patients, who received standard ticagrelor LD. Results: In the high LD group, PR in PRU (least-squares estimates, 95% CIs) tended to increase from Hour 0 (221.5, 200.5-242.4) to Hour 0.5 (257.8, 236.9-278.7), p=0.08. PR at Hour 1 (217.7, 196.8-238.6) did not differ compared to Hour 0 (p>0.99). PR observed at Hour 2 (110.5, 89.6-131.4) and Hour 4 (43.7, 22.8-64.6) was significantly decreased compared to Hour 0 (P<0.001 for both). The high PR rates (threshold 230 PRU) at Hour 0.5, 1, 2 and 4 were 78.6%, 52.4%, 23.8% and 2.4% respectively. In 22 propensity-matched pairs of patients, PR did not differ significantly between standard and high LD group at any time point (Table). View this table: Table 1. Platelet reactivity (VerifyNow PRU) at 0.5, 1, 2 and 4 hours post ticagrelor LD Conclusions: In STEMI patients treated with primary PCI, double the standard LD of ticagrelor results in no significant PR change at Hour 1 compared to baseline. At Hour 2, the double LD of ticagrelor achieves high platelet inhibition in the majority of patients. Double LD of ticagrelor did not appear superior to the standard LD in reducing PR the early hours after intake in STEMI.