Application Of DAPT Score To Guide Antiplatelet Drug Therapy After Stent Implantation In Patients With Chronic Total Occlusion

Objective: Percutaneous coronary intervention(PCI)has become the important treatment for patients with coronary heart disease.The use of stents requires patients to be under dual antiplatelet therapy(DAPT),but the optimal DAPT duration remains controversial.The incidence of thrombosis of chronic total occlusion(CTO)is higher than that of general lesions.Longer therapies have demonstrated increased benefit in reduction of ischemic event,but this benefit has been shadowed by the increase in bleeding events.DAPT score helps identify patients who benefit from prolonged DAPT after PCI.The 2016 American Heart Association/American College of Cardiology(AHA/ACC)recommended to use DAPT score to access patients.When the DAPT score ≥ 2,the risk of thrombosis is high,and the longer DAPT(12-30 months)has potential benefits.When the DAPT score < 2,the risk of thrombosis is low,and the longer DAPT has potential bleeding risk.However,the usefulness of the DAPT score in patients with CTO is uncertain.The aim of this study was to use DAPT score to guide the DAPT in patients undergoing PCI for CTO,so that providing the optimal DAPT duration and reducing the incidence of complications.Methods: Case source: selected 407 patients from January 1,2014 to June 30,2017,who confirmed the presence of CTO and underwent PCI successfully in the Department of Cardiology of Bethune International Peace Hospital of the People’s Liberation Army.All patients received aspirin 100 mg/d and clopidogrel 75 mg/d before PCI and reached the loading dose.After PCI,all patients continued to take aspirin 100mg/d and clopidogrel 75mg/d for at least 12 months.Patients were divided into two groups by DAPT score.I group(DAPT score ≥ 2): 202 patients.II group(DAPT score ≥2): 205 patients.Patients with a DAPT score ≥ 2 were divided into single antiplatelet therapy(SAPT)group and prolonged DAPT(12-58 months)group,and patients with a DAPT score < 2 were also divided into SAPT group and prolonged DAPT(12-58 months)group.The primary end point of the study was MACCE,including all-cause death,cardiac death,non-fatal myocardial infarction,target vessel revascularization,and ischemic stroke.The secondary endpoint was type 2,3,and 5 bleeding events defined by the Bleeding Academic Research Consortium(BARC).Results: Ⅰ group(DAPT score ≥ 2): the prolonged DAPT group included 109 patients and the SAPT group included 93 patients.II group(DAPT score < 2): the prolonged DAPT group included 117 patients,and the SAPT group included 88 patients.All patients were followed up and the follow-up deadline was December 31,2018.The median follow-up time was 34 months.Among patients with a DAPT score ≥ 2,the incidence of MACCE was statistically significant in prolonged DAPT group compared with SAPT group(5.5% vs 14%,P=0.040).Kaplan-Meier curve showed that patients with prolonged DAPT had lower MACCE-free incidence rates,the difference was statistically significant(P=0.046).Further analysis showed that the incidence of cardiac death and non-fatal myocardial infarction was significantly lower than that of the SAPT group(1.8% vs 9.7%,P=0.014;2.8% vs 9.7%,P=0.038,respectively),the difference was statistically significance.Compared with the SAPT group,the prolonged DAPT group decreased the incidence of ischemic stroke,target vessel revascularization,and all-cause mortality(1.8% vs 5.4%,P=0.324;1.8% vs 7.5%,P=0.107;2.8% VS 6.5%,P=0.353),but the difference was not statistically significant.In terms of secondary endpoints,the incidence of type 2,3,and 5 bleeding events defined by BARC was not statistically significant(3.7% vs 2.2%,P=0.827).Kaplan-Meier analysis showed that there was no significant difference in BARC2,3,and 5 bleeding events-free incidence rates between the prolonged DAPT group and the SAPT group(P=0.580).Among patients with a DAPT score < 2,the incidence of MACCE was similar between the prolonged DAPT group and the SAPT group(4.3% vs 6.8%,P=0.626),and the difference was not statistically significant.Kaplan-Meier curve showed that there was no significant difference in MACCE-free incidence rates(P=0.293).Compared with the SAPT group,the incidence of cardiogenic death,non-fatal myocardial infarction,ischemic stroke,target reconstruction and all-cause death was also not statistically significant(1.7% vs.3.4%,P=0.746;2.6% VS 5.7%,P=0.437;0.9% VS 3.4%,P=0.424;2.6% VS 4.5%,P=0.700;1.7% VS 3.4%,P=0.746).In terms of secondary endpoints,the incidence of type 2,3,and 5 bleeding events defined by BARC in the DAPT group significantly increased(12.8% vs 3.4%,P=0.018),the difference was statistically significant.Kaplan-Meier curve showed that patients with the SAPT had higher BARC 2,3,and 5 bleeding events-free incidence rates,the difference was statistically significant(P=0.034).Conclusion: For CTO patients with a DAPT score ≥2,prolonged DAPT reduced the incidence of MACCE,without increasing the risk of bleeding,and patients can benefit from prolonged DAPT.For patients with a DAPT score < 2,prolonged DAPT did not reduce the incidence of MACCE,but increased the risk of bleeding.Prolonged DAPT was harmful for patients.DAPT score was also applicable to patients with CTO.