Early Versus Delayed Invasive Strategies in High-Risk Non-ST Elevation Acute Coronary Syndrome Patients - A Systematic Literature Review and Meta-Analysis of Randomised Controlled Trials.

RATIONALE: It is unclear whether it is beneficial to perform angiography and/or percutaneous coronary intervention (PCI) as an early or delayed invasive strategy amongst high-risk non-ST elevation acute coronary syndrome (NSTEACS) patients.

OBJECTIVE: To determine whether an early invasive strategy could further reduce recurrent myocardial infarction (MI) and early mortality compared to a delayed invasive strategy.

METHODS AND RESULTS: We searched MEDLINE, CINAHL and SCOPUS and performed a meta-analysis of nine RCTs with a total of 5274 patients. No statistically significant difference in recurrent MI (RR=0.56, 95% CI 0.17-1.87, p=0.35), early mortality (RR=0.81, 95% CI 0.62-1.05, p=0.11) and major bleeding (RR=0.85, 95% CI 0.66-1.09, p=0.21) was found between groups. A statistically significant reduction in recurrent ischaemia was found amongst patients treated with an early invasive strategy (RR 0.45, 95% CI 0.26-0.78, p=0.004). Subgroup analysis for recurrent MI showed a statistically significant reduction in risk amongst patients treated <24hours compared to≥24hours (RR=0.31, 95% CI 0.11-0.89, p=0.03).

CONCLUSION: This study suggests that an early invasive strategy may not further reduce recurrent MI and early mortality, but may significantly reduce recurrent ischaemia. However, the recurrent MI endpoint was associated with heterogeneity due to inconsistent MI definitions and strategy timings amongst the included trials. Furthermore, subgroup analysis demonstrated a significant reduction in recurrent MI amongst patients treated <24hours. Therefore, large clinical trials with consistent inclusion criteria are required to confirm whether intervention within 24hours reduces the rate of spontaneous and post-discharge recurrent MI. Future studies with long-term follow-up data are required to detect relevant differences in early mortality. Currently, it appears that stabilised high-risk NSTEACS patients may be safely delayed up to 24hours before undergoing an early invasive strategy.