Effects of switching ticagrelor to clopidogrel on cardiovascular outcomes in patients with acute coronary syndrome

Present study was to evaluate whether switching ticagrelor to clopidogrel would impact platelet reactivity and cardiovascular outcomes in acute coronary syndrome (ACS) patients after percutaneous coronary intervention (PCI). A total of 202 ACS patients after PCI were enrolled and prescribed ticagrelor. Before discharge, 138 (68%) patients were switched to clopidogrel. Peripheral blood was obtained before switching and at 48 hours after switching to measure platelet reactivity. Patients were followed for 30 days to evaluate cardiovascular events. Compared to ticagrelor group, patients in clopidogrel group were more likely to be male (69.6% vs 65.6%), smokers (34.1% vs 31.3%) and had higher prevalence of hypertension (75.4% vs 71.9%). The frequency of right coronary artery lesion was significantly higher in ticagrelor group (34.4% vs 30.4%). There were no significant differences in baseline platelet reactivity (37.6 ± 5.2% vs 38.4 ± 4.9%). Forty-eight hours after switching to clopidogrel, platelet reactivity in clopidogrel group was significantly higher (46.3 ± 5.6% vs 38.1 ± 5.0%, P <.05). Patients in clopidogrel group had significantly higher incidence of cardiovascular events (3.6% vs 1.6%, P <.05). However, after further adjusted for platelet reactivity at 48 hours of switching, clopidogrel switching was not significantly associated with composite outcomes, with hazard ratio 1.08 (95% confidence interval 0.98–1.21, P = .063), indicating that platelet reactivity was a critical mediator between antiplatelet drug switching and cardiovascular outcomes. ACS patients after PCI treatment, early switching ticagrelor to clopidogrel results in increased platelet reactivity and higher incidence of short-term cardiovascular events.