P2Y₁₂ inhibitor pre-treatment in NSTE-ACS: translating trial evidence into UK clinical practice

Dual antiplatelet therapy is indicated in the management of non-ST-elevation acute coronary syndrome (NSTE-ACS) and can be administered before coronary angiography (pre-treatment) or after coronary anatomy is known. Based on clinical trials with rapid access to inpatient coronary angiography, clinical guidelines recommend invasive assessment prior to commencing a second antiplatelet. We aimed to evaluate the impact of a change in clinical policy from routine P2Y₁₂ inhibitor pre-treatment to no routine pre-treatment on in-hospital outcomes in a UK healthcare context.

A retrospective observational study of hospitalised NSTE-ACS patients with a planned invasive strategy at a tertiary cardiac centre in Northeast England was conducted. Two cohorts were identified: routine pre-treatment (1 January 2021 to 31 December 2021) and no routine pre-treatment (1 July 2022 to 30 June 2023). Primary endpoints were in-hospital ST-elevation myocardial infarction (STEMI) and actionable bleeding events, reported as propensity score-adjusted ORs (ORs) and 95% CIs.

Of 2506 NSTE-ACS cases, 1219 presented before and 1287 after the policy change, which was adhered to in most cases (84.2%). Median time from admission to angiography was 3.6 days (IQR 1.9, 5.8). In comparison to a routine pre-treatment strategy, a no routine pre-treatment strategy was associated with greater risk of in-hospital STEMI (1.7% vs 0.4%, adjusted OR 4.40, 95% CI 1.78 to 13.3), but lower risk of actionable bleeding events (0.2% vs 0.9%, adjusted OR 0.18, 95% CI 0.03 to 0.70). There was evidence of pre-treatment effect modification by procedural waiting time on in-hospital STEMI incidence (p for interaction=0.026).

We observed a greater risk of in-hospital STEMI but lower rates of bleeding following the change from a routine pre-treatment to a no routine pre-treatment strategy. UK waiting times for in-patient coronary angiography are typically considerably longer than the trials on which guidance is based, which may impact the risk/benefit balance in clinical practice.