Background: Supplemental oxygen (O2) is beneficial in patients with acute myocardial infarction (AMI) who have hypoxemia. However in patients who have suspected AMI without hypoxemia, the benefit of O2 remains uncertain. We conducted a meta-analysis, including the recent landmark trials, to establish the efficacy and safety of O2 in AMI.
Methods: We searched Medline, Embase, and Ovid SP databases for randomized clinical trials that compared O2 with room air in suspected AMI without hypoxemia. Hypoxemia was defined as O2 saturation of <90%. The primary endpoint was all-cause mortality. Data were pooled by the random effects model and I2 was used to assess for the heterogeneity.
Results: A total of 6 studies including 8193 participants were included in the final analysis. On pooled analysis, there was no significant difference between the two arms in 30-day all-cause mortality (OR=1.10 [0.67, 1.80]; p=0.70), cardiogenic shock (OR=0.75 [0.49, 1.16]; p=0.19), recurrent myocardial infarction (OR=1.24 [0.46, 3.34]; p=0.67) and left ventricular ejection fraction (SMD= -1.95 [-4.76, 0.85]; p=0.17).
Conclusion: Contrary to the routine clinical practice, our analysis shows that O2 administration does not provide any benefit in AMI patients who have normal oxygen saturation. It is reasonable to reserve O2 only for patients with AMI and hypoxemia.