Comparison between ticagrelor and clopidogrel on myocardial blood flow in patients with acute coronary syndrome, using 13 N-ammonia positron emission tomography

Background The PLEIO (comParison of ticagrelor and clopidogrEl on mlcrocirculation in patients with acute cOronary syndrome) study showed that 6 months of ticagrelor therapy significantly improved microvascular dysfunction in acute coronary syndrome (ACS) patients with stent implantation compared to clopidogrel. Improved microvascular function may affect myocardial blood flow (MBF). We compared the effects of ticagrelor and clopidogrel on MBF over a 6-month follow-up period among patients diagnosed with ACS treated with percutaneous coronary intervention (PCI). Methods In the PLEIO trial, 120 participants were randomized to receive ticagrelor 90 mg twice daily or clopidogrel 75 mg once daily after at least 6 months. 13 N-ammonia positron emission tomography (PET) imaging was performed in 94 patients to measure MBF at the 6-month follow-up visit. Results On a per-patient level, MBF (1.88 +/- 0.52 versus 1.67 +/- 0.64 mL/min per gram, P = .01) was significantly higher with ticagrelor compared with clopidogrel in the hyperemic state, but not under resting state (0.75 +/- 0.24 versus 0.75 +/- 0.19 mL/min per gram, P = .84). On a culprit-vessel analysis, the resting MBF was similar (0.69 +/- 0.20 versus 0.70 +/- 0.21, P = .89) between the two groups. However, the hyperemic MBF and myocardial flow reserve in the ticagrelor group were significantly higher compared with clopidogrel (1.75 +/- 0.46 versus 1.52 +/- 0.59, P = .03 and 2.71 +/- 0.89 versus 2.20 +/- 0.81, P = .02, respectively). These differences were not observed in non-culprit vessels. Conclusions Maintenance treatment of ticagrelor increased the hyperemic MBF and myocardial flow reserve compared with clopidogrel.