Early Coronary Angiography in Patients With Out-of-Hospital Cardiac Arrest Without ST-Segment Elevation: A Systematic Review, Meta-Analysis, and Comparative Analysis of Studies

Out-of-hospital cardiac arrest has a high mortality rate. Unlike ST-elevation myocardial infarction, the results of performing early coronary angiography (CAG) in non-ST-elevation myocardial infarction patients are controversial. This study aimed to compare early and nonearly CAG in this population, in addition to the identification of differences between randomized controlled trials (RCTs) and observational studies conducted in this regard. A systematic search in PubMed, Embase, and Cochrane library was performed to identify the relevant studies. Random-effect meta-analysis was done to calculate the pooled effect size of early versus nonearly CAG outcomes in all studies in addition to each of the RCT and observational subgroups of the studies. The relative risk ratio (RR), along with its 95% confidence interval (CI), was used as a measure of difference. A total of 16 studies including 5234 cases were included in our analyses. Compared with observational cohorts, RCT studies had patients with higher baseline comorbidities (older age, hypertension, diabetes, and coronary artery disease). Random-effect analysis revealed a lower rate of in-hospital mortality in the early-CAG group (RR, 0.79; 95% CI, 0.65-0.97; P = 0.02); however, RCT studies did not find a statistical difference in this outcome (RR, 1.01; 95% CI, 0.83-1.23; P = 0.91). Moreover, mid-term mortality rates were lower in the early-CAG group (RR, 0.87; 95% CI, 0.78-0.98; P = 0.02), mostly due to observational studies. There was no significant difference between the groups in other efficacy and safety outcomes. Although early CAG was associated with lower in-hospital and mid-term mortality in overall analyses, no such difference was confirmed by the results obtained from RCTs. Current evidence from RCTs may not be representative of real-world patients and should be interpreted within its limitation.