Immediate vs delayed intervention for acute coronary syndromes: a randomized clinical trial.

Context: International guidelines recommend an early invasive strategy for patients with high-risk acute coronary syndromes without ST-segment elevation, but the optimal timing of intervention is uncertain.

Objective: To determine whether immediate intervention on admission can result in a reduction of myocardial infarction compared with a delayed intervention.

Design, Setting, And Patients: The Angioplasty to Blunt the Rise of Troponin in Acute Coronary Syndromes Randomized for an Immediate or Delayed Intervention (ABOARD) study, a randomized clinical trial that assigned, from August 2006 through September 2008 at 13 centers in France, 352 patients with acute coronary syndromes without ST-segment elevation and a Thrombolysis in Myocardial Infarction (TIMI) score of 3 or more to receive intervention either immediately or on the next working day (between 8 and 60 hours after enrollment).

Main Outcome Measures: The primary end point was the peak troponin value during hospitalization; the key secondary end point was the composite of death, myocardial infarction, or urgent revascularization at 1-month follow-up.

Results: Time from randomization to sheath insertion was 70 minutes with immediate intervention vs 21 hours with delayed intervention. The primary end point did not differ between the 2 strategies (median [interquartile range] troponin I value, 2.1 [0.3-7.1] ng/mL vs 1.7 [0.3-7.2] ng/mL in the immediate and delayed intervention groups, respectively; P = .70). The key secondary end point was observed in 13.7% (95% confidence interval, 8.6%-18.8%) of the group assigned to receive immediate intervention and 10.2% (95% confidence interval, 5.7%-14.6%) of the group assigned to receive delayed intervention (P = .31). The other end points, as well as major bleeding, did not differ between the 2 strategies.

Conclusion: In patients with acute coronary syndromes without ST-segment elevation, a strategy of immediate intervention compared with a strategy of intervention deferred to the next working day (mean, 21 hours) did not result in a difference in myocardial infarction as defined by peak troponin level.

Trial Registration: clinicaltrials.gov Identifier: NCT00442949.