P1931Effect of de-escalated switching dual antiplatelet therapy after acute myocardial infarction in patients undergoing percutaneous coronary intervention: real-world data from a nationwide cohort study

Background Recently, both unguided (platelet function testing independent) and guided (platelet function testing dependent) DAPT de-escalation strategies have been investigated in different clinical studies but the data is still limited and conflicting. The aim of this study was to examine the effect of switching dual antiplatelet therapy (DAPT) on the major vascular risk after acute myocardial infarction (AMI) in patients undergoing percutaneous coronary intervention (PCI) by using Taiwan National Health Insurance Research Database. Methods In total, 1,903 and 4,059 patients defined as switched to aspirin and clopidogrel (switched DAPT) and continuation of aspirin and ticagrelor (unswitched DAPT) cohort, respectively who had received PCI during AMI hospitalization, on aspirin and ticagrelor initially and without occurring adverse events at 3 months were evaluated between 2013 and 2015. An inverse probability treatment of weighted approach was adopted to balance the baseline differences between two groups and Cox proportional hazard regression and competing risk regression were used to evaluated the effect of switching DAPT on death, AMI readmission, major bleeding and non-major clinically relevant bleeding. Results The incidence rates (per 100 person-year) of death and AMI readmission were 3.97 (95% confidence interval [CI] = 3.19–4.84) and 3.84 (95% CI = 3.09–4.73) in switched cohort and 1.83 (95% CI = 1.47–2.24) and 2.23 (95% CI = 1.82–2.68) in unswitched cohort, respectively. After adjustment for patients' clinical variables, switched cohort had higher risk of death (adjusted hazard ratio = 2.18, 95% CI = 1.62–2.93, P<0.001), and AMI readmission (adjusted sub-distribution ratio = 1.72, 95% CI = 1.27–2.34, P<0.001) compared to these in unswitched cohort; however, there was no difference in the risk of bleeding. Subgroup analysis showed a similar findings in many specific groups, except the patients who were younger age and had lower comorbidity score. Conclusion Switching DAPT might increase the risk of death and AMI readmission among patients with AMI undergoing PCI.