Supplemental oxygen has been commonly used in the cases of acute coronary syndrome (ACS); however, recent evidence suggests that high-concentration oxygen supplementation and hyperbaric oxygen in ACS patients are associated with adverse cardiovascular effects. The purpose of this article is to systematically review the role of supplemental oxygen therapy in normoxemic patients with ACS. A search for randomized controlled trials before November 2017 in biomedical databases was performed, and a total of 6 eligible studies with 7508 participants were identified. Four studies reported all-cause mortality after randomization, whereas 3 studies measured myocardial infarct size using cardiac enzyme levels and magnetic resonance imaging. The effect size of our primary end point was the odds ratio for all-cause mortality. The mean difference was calculated as a secondary outcome for myocardial infarct size. Compared with ambient air or titrated oxygen, high-concentration oxygen therapy did not significantly decrease all-cause mortality (odds ratio, 1.01; 95% confidence interval [CI], 0.81-1.25; P = .95) within 1 year nor infarct size detected by peak cardiac troponin (mean difference, -0.53 ng/mL; 95% CI, -1.20 to 0.14; P = .12) and magnetic resonance imaging (mean difference, 1.45 g; 95% CI, -1.82 to 4.73; P = .39). These outcomes were listed through a fixed-effects model because of low statistical heterogeneity across the studies.

Hu, Cheng, Yin, Ning, Xiang, Zhou (2018). The Role of Oxygen Therapy in Normoxemic Acute Coronary Syndrome: A Systematic Review of Randomized Controlled Trials. The Journal of cardiovascular nursing, ;33(6):559-567. https://www.ncbi.nlm.nih.gov/pubmed/30024486