Background: Studies assessing the timing of percutaneous coronary interventions (PCI) in patients with Non-ST segment elevation Acute Coronary Syndromes (NSTE-ACS) have failed to generate a consensus on how early PCI should be performed in such patients.

Purpose: This meta-analysis compares clinical outcomes at 30 days in NSTE-ACS patients undergoing PCI within 24 hours of presentation (early PCI) with those receiving PCI more than 24 hours after presentation (delayed PCI).

Data sources: Data were extracted from searches of MEDLINE (1990-2010) and Google scholar and from scrutiny of abstract booklets from major cardiology meetings (1990-2010).

Study selection: Randomized clinical trials (RCTs) that included the composite endpoint of death and non-fatal myocardial infarction (MI) at 30 days after PCI were considered.

Data extraction: Two independent reviewers extracted data using standard forms. The effects of early and delayed PCI were analyzed by calculating pooled estimates for death, non-fatal MI, bleeding, repeat revascularization and the composite endpoint of death or non-fatal MI at 30 days. Univariate analysis of each of these variables was used to create odds ratios.

Data synthesis: Seven studies with a total of 13,762 patients met the inclusion criteria. There was no significant difference in the odds of the composite endpoint of death or non-fatal MI at 30 days between patients undergoing early PCI and those receiving delayed PCI (OR-0.83, 95%CI 0.62-1.10). Patients receiving delayed PCI experienced a 33% reduction in the odds of repeat revascularization at 30 days compared to those undergoing early PCI (OR-1.33, 95%CI 1.14-1.56, P=0.0004).Conversely, patients undergoing early PCI experienced lower odds of bleeding than those receiving delayed PCI (OR-0.76, 95%CI 0.63-0.91, P = 0.0003).

Conclusions: In NSTE-ACS patients early PCI doesn't reduce the odds of the composite endpoint of death or non-fatal MI at 30 day. This strategy is associated with lower odds of bleeding and higher odds of repeat revascularization at 30 days than a strategy of delayed PCI.