Abstract: AIM To evaluate the efficacy and safety of ticagrelor in patients with ST elevation myocardial infarction (STEMI) undergoing rescue PCI for failed thrombolysis. METHODSTwo hundred and forty-six consecutive STEMI patients undergoing rescue PCI for failed thrombolysis were randomly assigned to ticagrelor group (180 mg loading dose followed by 90 mg bid) or to clopidogrel group (300 mg loading dose followed by 75 mg qd) for 12 months. All patients were given aspirin (100 mg qd). Myocardial perfusion was assessed by TFG, CTFC and TMPG. Major adverse cardiovascular and cerebrovascular events (cardiovascular death, nonfatal myocardial infarction, stroke, target vessel revascularization and stent thrombosis formation) and clinical complications were evaluated. RESULTSThe primary composite endpoint occurred in fewer patients in ticagrelor group than in clopidogrel group (6.6% vs. 15.2% HR=0.395, 95%CI: 0.166-0.940, P<0.05). There was no significant difference between clopidogrel and ticagrelor groups in the rates of total major bleeding or severe bleeding. CONCLUSIONTicagrelor appears to be a safer and more efficacious option than clopidogrel for STEMI patients undergoing rescue PCI for failed thrombolysis.