To determine the optimal timing of catheterization in high risk acute coronary syndromes.

The randomized ABOARD study showed that in patients with acute coronary syndromes without ST-segment elevation, a “primary PCI” strategy compared with a strategy of intervention deferred to the next working day did not result in a difference in clinical outcome. We performed a new analysis of the ABOARD population which was divided into quartiles of time from randomization to catheterization. Like in the main analysis the primary endpoint was the peak troponin value during hospitalization and the key secondary end point was the composite of death, myocardial infarction, or urgent revascularization at 1 month follow-up.

The population (n = 352) was divided into four quartile-groups. In the first quartile, catheterization was performed within the first 69 minutes (median: 50 minutes) after randomization, in the second group between 69 and 339 minutes (median: 118 minutes), in the third one between 339 and 1247 min (median: 1048 minutes) and in the last one over 1247 minutes (median 1448 minutes).

received intense antiplatelet therapy with a mean 660mg (±268) loading dose and 111mg (±40) maintenance dose of clopidogrel while 99% of the PCI patients received abciximab. Low-molecular-weight-heparins were used in 68% of patients and radial approach was predominant (84%).The mean (+/−SD) peak of troponin did not differ between the 4 groups (Q1 = 7.5ng/mL±12.3, Q2 = 9ng/mL±22.5, Q3=7ng/mL±12.3, Q4 = 6.4ng/mL±13.5) p = 0.66). The 30-day rate of death, myocardial infarction and urgent revascularization did not differ between the four groups. (Q1 = 20%) (23%), Q2 = 20 (23%) Q3=14 (16.1%), Q4 = 20 (22.7) p = 0.61). Rates of major bleeding complications were also similar in the four groups.

This refined analysis of the ABOARD study confirms the primary analysis of the two groups formed by randomization. Time to catheterization has no impact on clinical outcome when performed swiftly within the first 24 hours of admission.