A change from routine P2Y12 inhibitor pre-treatment to no routine pre-treatment in NSTE-ACS was associated with greater risk of in-hospital STEMI but lower rates of actionable bleeding, with evidence that prolonged UK waiting times for coronary angiography may impact the risk/benefit balance compared to the trial settings on which guidelines are based.
Key Findings
Results
A no routine pre-treatment strategy was associated with significantly greater risk of in-hospital STEMI compared to routine pre-treatment.
In-hospital STEMI occurred in 1.7% of the no routine pre-treatment cohort vs 0.4% of the routine pre-treatment cohort.
Adjusted OR 4.40 (95% CI 1.78 to 13.3) for in-hospital STEMI with no routine pre-treatment strategy.
Analysis was propensity score-adjusted to account for differences between cohorts.
Study included 2506 NSTE-ACS cases: 1219 in the pre-treatment period and 1287 in the no routine pre-treatment period.
Results
A no routine pre-treatment strategy was associated with significantly lower risk of actionable bleeding events compared to routine pre-treatment.
Actionable bleeding events occurred in 0.2% of the no routine pre-treatment cohort vs 0.9% of the routine pre-treatment cohort.
Adjusted OR 0.18 (95% CI 0.03 to 0.70) for actionable bleeding with no routine pre-treatment strategy.
Both primary endpoints—in-hospital STEMI and actionable bleeding—were reported as propensity score-adjusted ORs with 95% CIs.
Results
Procedural waiting time significantly modified the effect of pre-treatment on in-hospital STEMI incidence.
There was evidence of pre-treatment effect modification by procedural waiting time on in-hospital STEMI incidence (p for interaction=0.026).
Median time from admission to angiography was 3.6 days (IQR 1.9, 5.8).
This waiting time is described as considerably longer than in the clinical trials on which current guidelines are based.
Methods
The policy change from routine pre-treatment to no routine pre-treatment was adhered to in most but not all cases.
Policy adherence was 84.2% following the change to no routine pre-treatment.
The study was a retrospective observational study at a tertiary cardiac centre in Northeast England.
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).
Discussion
UK inpatient waiting times for coronary angiography are considerably longer than in the clinical trials that informed current guidelines recommending no routine pre-treatment.
Median time from admission to angiography in this UK cohort was 3.6 days (IQR 1.9, 5.8).
Current guidelines recommend invasive assessment prior to commencing a second antiplatelet, based on trials with rapid access to inpatient coronary angiography.
The authors note this discrepancy 'may impact the risk/benefit balance in clinical practice' in UK settings.
What This Means
This research studied what happened when a UK heart centre changed its policy on when to give a second blood-thinning medication (a P2Y12 inhibitor) to patients admitted with a type of heart attack called NSTE-ACS. Under the old policy, this medication was given routinely upon admission, before doctors knew what was happening in the patient's coronary arteries. Under the new policy—which follows current clinical guidelines—the medication was withheld until after a diagnostic procedure (coronary angiography) confirmed it was needed. The study compared outcomes for 2,506 patients treated under each policy between 2021 and 2023.
This research suggests that switching to the no routine pre-treatment policy came with a meaningful trade-off: patients were less likely to have a significant bleeding complication (0.2% vs 0.9%), but more likely to suffer a serious heart attack (STEMI) while waiting in hospital (1.7% vs 0.4%). Importantly, the study found that the length of time patients waited for their diagnostic procedure appeared to influence this risk—the longer the wait, the more relevant the pre-treatment decision became. The average wait in this UK hospital was 3.6 days, which is substantially longer than the waiting times in the clinical trials that were used to develop the current guidelines.
The practical implication highlighted by this research is that guidelines developed from trials conducted in settings with very fast access to coronary angiography may not translate equally well to healthcare systems where patients routinely wait several days for the procedure. The findings suggest that the balance between the benefit of preventing heart attacks through early medication and the risk of causing bleeding may differ depending on how long a patient waits for angiography, and that this context may need to be considered when applying international guidelines to UK clinical practice.