Optimal timing for an early invasive strategy in patients with non-ST-segment-elevation acute coronary syndrome remains unclear. We evaluated the relationship between time from hospital admission to coronary angiography and outcomes in high-risk patients with non-ST-segment-elevation acute coronary syndrome who underwent angiography within 48 hours of admission.
Data from 10 027 patients enrolled in the Superior Yield of the New Strategy of Enoxaparin, Revascularization, and Glycoprotein IIb/IIIa Inhibitors (SYNERGY) trial were analyzed. Patients were grouped by 6-hour intervals of time from hospital admission to coronary angiography. Primary outcomes were 30-day death or myocardial infarction, in-hospital Thrombolysis In Myocardial Infarction (TIMI) and Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries (GUSTO) major bleeding, and blood transfusion. Adjusted estimates of event rates were obtained by use of a multivariable methodology that included possible confounders through baseline and accounted for propensity of time to angiography. The landmark method was used to calculate odds ratios and 95% confidence intervals of outcomes for each time period adjusted for baseline and postbaseline clinical events. Overall, 9216 patients (92%) underwent angiography, 6352 (63%) within 48 hours. Unadjusted and adjusted rates of death/myocardial infarction increased with increasing time to angiography. The adjusted odds ratio for death/myocardial infarction in patients receiving angiography in <6 hours was 0.56 (95% confidence interval 0.41 to 0.74), whereas after 30 hours, there was no significant benefit compared with further delayed angiography. Major bleeding and transfusion did not vary significantly across time-to-angiography intervals.
A decrease in the time to coronary angiography was associated with fewer ischemic outcomes and no increase in bleeding. Randomized clinical trials are needed to provide definitive evidence on optimal timing of coronary angiography but are difficult to design and conduct. Ongoing trials should instead clarify whether delaying angiography to administer aggressive upstream antithrombotic therapies is effective in the current setting of non-ST-segment-elevation acute coronary syndrome management.