High bleeding risk (HBR) and acute coronary syndrome (ACS) subtypes are critical in determining bleeding and cardiovascular event risk after percutaneous coronary intervention (PCI).

In 4476 ACS patients enrolled in the STOPDAPT-3, where the no-aspirin and dual antiplatelet therapy (DAPT) strategies after PCI were randomly compared, the pre-specified subgroup analyses were conducted based on HBR/non-HBR and ST-segment elevation myocardial infarction (STEMI)/non-ST-segment elevation ACS (NSTE-ACS). The co-primary bleeding endpoint was Bleeding Academic Research Consortium (BARC) type 3 or 5, and the co-primary cardiovascular endpoint was a composite of cardiovascular death, myocardial infarction, definite stent thrombosis, or ischaemic stroke at 1 month. Irrespective of the subgroups, the effect of no-aspirin compared with DAPT was not significant for the bleeding endpoint (HBR [N = 1803]: 7.27 and 7.91%, hazard ratio (HR) 0.91, 95% confidence interval (CI) 0.65–1.28; non-HBR [N = 2673]: 3.40 and 3.65%, HR 0.93, 95% CI 0.62–1.39; Pinteraction = 0.94; STEMI [N = 2553]: 6.58 and 6.56%, HR 1.00, 95% CI 0.74–1.35; NSTE-ACS [N = 1923]: 2.94 and 3.64%, HR 0.80, 95% CI 0.49–1.32; Pinteraction = 0.45), and for the cardiovascular endpoint (HBR: 7.87 and 5.75%, HR 1.39, 95% CI 0.97–1.99; non-HBR: 2.56 and 2.67%, HR 0.96, 95% CI 0.60–1.53; Pinteraction = 0.22; STEMI: 6.07 and 5.46%, HR 1.11, 95% CI 0.81–1.54; NSTE-ACS: 3.03 and 1.71%, HR 1.78, 95% CI 0.97–3.27; Pinteraction = 0.18).

In patients with ACS undergoing PCI, the no-aspirin strategy compared with the DAPT strategy failed to reduce major bleeding events irrespective of HBR and ACS subtypes. The numerical excess risk of the no-aspirin strategy relative to the DAPT strategy for cardiovascular events was observed in patients with HBR and in patients with NSTE-ACS.