RCT: In MI without hypoxemia, supplemental oxygen vs ambient air did not differ for death or rehospitalization with MI or HF at 1 y in patients with or without diabetes.
Nystrom T, James SK, Lindahl B, et al. Oxygen Therapy in Myocardial Infarction Patients With or Without Diabetes: A Predefined Subgroup Analysis From the DETO2X-AMI Trial. Diabetes Care. 2019 Nov;42(11):2032-2041. doi: 10.2337/dc19-0590. Epub 2019 Aug 31.

OBJECTIVE: To determine the effects of oxygen therapy in myocardial infarction (MI) patients with and without diabetes.

RESEARCH DESIGN AND METHODS: In the Determination of the Role of Oxygen in Suspected Acute Myocardial Infarction (DETO2X-AMI) trial, 6,629 normoxemic patients with suspected MI were randomized to oxygen at 6 L/min for 6-12 h or ambient air. In this prespecified analysis involving 5,010 patients with confirmed MI, 934 had known diabetes. Oxidative stress may be of particular importance in diabetes, and the primary objective was to study the effect of supplemental oxygen on the composite of all-cause death and rehospitalization with MI or heart failure (HF) at 1 year in patients with and without diabetes.

RESULTS: As expected, event rates were significantly higher in patients with diabetes compared with patients without diabetes (main composite end point: hazard ratio [HR] 1.60 [95% CI 1.32-1.93], P < 0.01). In patients with diabetes, the main composite end point occurred in 16.2% (72 of 445) allocated to oxygen as compared with 16.6% (81 of 489) allocated to ambient air (HR 0.93 [95% CI 0.67-1.27], P = 0.81). There was no statistically significant difference for the individual components of the composite end point or the rate of cardiovascular death up to 1 year. Likewise, corresponding end points in patients without diabetes were similar between the treatment groups.

CONCLUSIONS: Despite markedly higher event rates in patients with MI and diabetes, oxygen therapy did not significantly affect 1-year all-cause death, cardiovascular death, or rehospitalization with MI or HF, irrespective of underlying diabetes, in line with the results of the entire study.

Ratings
Specialty Area Score
Hospital Doctor/Hospitalists
Internal Medicine
Family Medicine (FM)/General Practice (GP)
General Internal Medicine-Primary Care(US)
Emergency Medicine
Cardiology
Comments from MORE raters

Cardiology

It will take 10 years before paramedics, nurses, and doctors automatically stop giving O2 to MI patients.

Emergency Medicine

This is a subgroup re-analysis of a previous trial asking whether supplemental oxygen benefits normoxemic patients with suspected MI with or without diabetes. The original study was well done. This analysis shows no benefit or harm for supplemental oxygen for both diabetic and non-diabetic patients. At least one other study showed harm to suspected MI patients, so clinicians are still left with doubt about whether to give their suspected MI patients supplemental oxygen.

Yet another paper that tells us how oxygen is bad. This one focuses on a much narrower group (DM with MI) but still reinforces that only hypoxic patients need O2. Put down the nasal cannula.

Family Medicine (FM)/General Practice (GP)

This information is consistent with current guidelines and past evidence showing no benefit to routine oxygen administration in those with suspected myocardial infarction.

General Internal Medicine-Primary Care(US)

This is an important prespecified subgroup analysis of diabetics and the use of supplemental oxygen during an acute myocardial infarction. Similar to the overall trial, diabetics with normal oxygen saturation did not benefit from supplemental oxygen. Although the results were not statistically significant, the trend was toward worse outcomes (mortality, readmission) if given oxygen. Given the consistency with the full study data, clinicians should adhere to current recommendations in all patients and withhold supplemental oxygen in patients with normal oxygen saturation.

Hospital Doctor/Hospitalists

In this article the authors perform a subset analysis from the randomized detox-AMI trial looking at just the diabetics in that trial. They found that groups given oxygen in acute MI did not have worsening outcomes. As a hospitalist, the information that oxygen might be harmful is critical, and represents an implementation challenge for hospitals everywhere. Hospitals very closely monitor low oxygen and have alarms set for this; monitoring for elevated oxygen saturation is not routinely done, and because of prior conventional wisdom, providers see adding oxygen as the cure for dyspnea of all causes, potentially setting patients up for larger infarcts and worsening outcomes. I believe the 2017 AVOID trial and the results of DETOX-AMI are clear. We should be closely monitoring patients to avoid iatrogenic injury that comes with attempted good will delivered via nasal cannula, and should develop systems to implement this new information immediately.

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