Abstract:Objective To investigate the safety of an antiplatelet aggregation VerifyNow-P2Y12 in the guidance of low dose ticagrelor in patients with acute ST segment elevation myocardial infarction (STEMI) after emergency percutaneous coronary intervention (PCI). Methods A total of 100 patients with STEMI who received emergency PCI from May 2017 to May 2018 were selected.All the patients were treated with ticagrelor 90 mg twice a day for 30 days after PCI.Then,50 patients were selected randomly as the standard dose group,and continued to take the original dose until 12 months after operation.The other 50 patients (reduction group),the baseline value of VerifyNow-P2Y12 was measured,and ticagrelor was reduced to 45 mg twice a day for oral administration;after one week,VerifyNow-P2Y12 was retested,if P2Y12 reaction unit (PRU) was 40-150,ticagrelor was taken twice a day for oral administration for 12 months after PCI;if PRU was less than 40,ticagrelor was stopped and replaced by clopidogrel,and the study was excluded.A comparative study was carried out between the two groups.At 12 months after PCI,the main efficacy endpoints of the two groups were observed (including bleeding events,cardiovascular death,recurrent acute myocardial infarction and stroke complex events). Results Forty-four patients in the reduction group and 50 patients in the standard dose group were included in the study.At 12 months after PCI,no cardiac death,recurrent acute myocardial infarction or stroke occurred in both groups;but 16 bleeding events occurred.According to the TIMI standard definition of bleeding events,there were 3 cases (6.8%) in the reduction group and 13 cases (26.0%) in the standard dose group(χ²=6.10,P=0.01).In the reduction group,there were no case in major bleeding event and 3 cases in minor bleeding.In the standard dose group,the main bleeding events were gastrointestinal bleeding in 2 cases,and minor bleeding in 8 cases.According to GUSTO bleeding grading standard,there was no serious or life-threatening bleeding in the reduction group,and 1 case (gastrointestinal bleeding) in the standard dose group. ConclusionAfter STEMI emergency PCI,the antiplatelet aggregation therapy with ticagrelor 45 mg twice a day is safe,and the incidence of bleeding events is lower than that of the conventional dose therapy.