Background: Patients with out-of-hospital cardiac arrest (OHCA) present a challenge to health care providers due to the dramatic implications on mortality and neurological outcomes. Optimal treatment strategy is crucial for these patients. Emergency coronary angiography (CAG) improves outcomes of patients presenting with ST-elevation myocardial infarction after return of spontaneous circulation. Whether emergency CAG is also beneficial for patients without ST-elevation myocardial infarction remains controversial. 

Objective: The objective of this meta-analysis was to assess the effect of early CAG compared to late and no CAG for patients with OHCA and without ST-elevation myocardial infarction.

Methods: A systematic literature search was performed using the EMBASE, MEDLINE and Web of Science databases. Randomized and non-randomized controlled trials comparing the effect of early CAG to late and no CAG after OHCA without ST-elevation myocardial infarction were included. Meta-analyses using the Mantel-Haenszel Method based on a random effects model were performed to analyze the effect on survival and neurological outcomes. Additionally, Bayesian network meta-analyses were performed to compare early, late and no CAG separately. 

Results: 16 potential studies were identified by the literature search. After exclusion of two studies because of critical risk of bias, 14 studies were ultimately included in the quantitative analysis. Meta-analyses showed increased survival after early CAG compared to late and no CAG in the overall analysis (OR 1.37, 95% CI [1.07 to 1.76], p < 0.001, I2 = 73%, moderate heterogeneity). This effect was lost in the subgroup analysis of randomized controlled trials (OR 0.83, 95% CI [0.66 to 1.06], p = 0.53, I2 = 0%, no heterogeneity]. Neurological outcome was not improved after early CAG compared to late and no CAG (OR 1.32, 95% CI [0.99 to 1.76], p = 0.08, I2 = 53%, moderate heterogeneity). Network meta-analyses showed best survival after late CAG (late vs. early CAG: OR 4.20, 95% CI [1.22 to 20.91]; late vs. no CAG: OR 19.51, 95% CI [5.06 to 128.95]). Late CAG was also associated with better neurological outcome compared to no CAG (OR 20.11, 95% CI [3.28 to 513.35]). No significant difference in good neurological outcome was observed between late and early CAG (OR 4.17, 95% CI [0.93 to 65.95]). 

Conclusions: Previously reported superiority of early CAG after OHCA without ST-elevation myocardial infarction is based on high risk of bias non-randomized controlled trials. Meta-analyses of randomized trials do not support routinely performing early CAG in these patients. However, not performing CAG during index hospitalization was associated with increased mortality and worse neurological outcome. Whether late CAG is ultimately superior to early CAG should be evaluated in future randomized controlled trials. These trials should also assess the optimal timing of CAG.