518 Optimal Duration of Dual Antiplatelet Therapy After Coronary Stent Implantation: A Population-Based Retrospective Cohort Study

Abstract

Studies have shown non-inferiority of short-term vs 12-month dual antiplatelet therapy (DAPT) following PCI with stents. Others have shown better ischemic outcomes with extended DAPT (>12-months) at the expense of bleeding. To investigate associations between DAPT (aspirin+clopidogrel) duration following PCI and ischemic and bleeding outcomes under real-world conditions. Patients ≥65 years who had a PCI with stent in WA hospitals between 2003-2008 and survived 1-year (1-year landmark) and 2-years (2-year landmark) following discharge were identified from linked hospital admissions data. Associations between DAPT duration (from Pharmaceutical Benefits Scheme data) and 1- and 3-year outcomes of all-cause death, ACS, coronary artery revascularisation, stroke and major bleeding admissions, and composite (MACCE) were assessed using adjusted Cox regression models. There were 6678 patients with mean age 74.5 years and 67% males. 1-year landmark analysis showed a non-significant decreasing trend for MACCE with increasing DAPT duration. Risk of MACCE was lowest for 9-12 month DAPT (1-year HR 0.93, 95% CI 0.66-1.32 and 3-year HR 0.89, 95% CI 0.72-1.11) compared to 0-3 months DAPT. 3-year major bleeding for 9-12 months DAPT was not significantly different to 0-3 months (HR 0.74, 95% CI 0.39-1.42). Results were similar for 2-year landmark with no significant differences between 12-18 or 18-24 months DAPT vs 0-6 months for MACCE and major bleeding outcomes. DAPT duration of 6 months or less following PCI may be adequate to balance outcomes of MACCE and major bleeding in the era of bare metal and 1st/2nd generation drug eluting stents.