Abstract

Background A routine invasive strategy is recommended in the management of higher risk patients with non-ST elevation acute coronary syndromes (NSTE-ACS). However, patients with previous coronary artery bypass graft surgery (CABG) were excluded from key trials that informed these guidelines. Thus, the benefit of a routine invasive strategy is less certain in this specific subgroup. Methods A systematic review and meta-analysis of randomized controlled trials (RCT) was conducted. Eligible studies were RCTs of routine invasive versus a conservative or selective invasive strategy in patients presenting with NSTE-ACS that included patients with previous CABG. Summary data was collected from the authors of each trial if not previously published. Outcomes assessed were all-cause mortality, cardiac mortality, myocardial infarction and cardiac related hospitalization. Using a random-effects model, risk ratios with 95% confidence intervals were calculated. Results Summary data was obtained from eleven RCTs, including previously unpublished subgroup outcomes of nine trials, comprising 897 patients with previous CABG (477 routine invasive, 420 conservative/selective invasive). A routine invasive strategy did not reduce all-cause mortality (RR 1.12, 95% CI 0.97-1.29), cardiac mortality (RR 1.05, 95% CI 0.70-1.58), myocardial infarction (RR 0.90, 95% CI 0.65-1.23) or cardiac related hospitalization (RR 1.05, 95% CI 0.78-1.40). Conclusions This is the first meta-analysis assessing the effect of a routine invasive strategy in patients with prior CABG who present with NSTE-ACS. The results confirm the under-representation of this patient group in RCTs of invasive management in NSTE-ACS and suggest there is no benefit to a routine invasive strategy compared to a conservative approach with regard to major adverse cardiac events. These findings should be validated in an adequately powered RCT.