Development of a risk score for predicting the benefit versus harm of extending dual antiplatelet therapy beyond 6 months following percutaneous coronary intervention for stable coronary artery disease

BACKGROUND: Decisions on dual antiplatelet therapy (DAPT) duration should balance the opposing risks of ischaemia and bleeding. Our aim was to develop a risk score to identify stable coronary artery disease (SCAD) patients undergoing PCI who would benefit or suffer from extending DAPT beyond 6 months. METHODS: Retrospective analysis of a cohort of patients who completed 6 months of DAPT following PCI. Predictors of ischaemic and bleeding events for the 6-12 month period post-PCI were identified and a risk score was developed to estimate the likelihood of benefiting from extending DAPT beyond 6 months. Incidence of mortality, ischaemic and bleeding events for patients treated with DAPT for 6 vs. 6-12 months, was compared, stratified by strata of the risk score. RESULTS: The study included 2,699 patients. Over 6 months' follow up, there were 78 (2.9%) ischaemic and 43 (1.6%) bleeding events. Four variables (heart failure, left ventricular ejection fraction ≤30%, left main or three vessel CAD, status post (s/p) PCI and s/p stroke) predicted ischemic events, two variables (age>75, haemoglobin <10 g/dL) predicted bleeding. In the lower stratum of the risk score, 6-12 months of treatment with DAPT resulted in increased bleeding (p = 0.045) with no decrease in ischaemic events. In the upper stratum, 6-12 months DAPT was associated with reduced ischaemic events (p = 0.029), with no increase in bleeding. CONCLUSION: In a population of SCAD patients who completed 6 months of DAPT, a risk score for subsequent ischaemic and bleeding events identified patients likely to benefit from continuing or stopping DAPT.