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DETO2X-SWEDEHEART: Oxygen treatment not beneficial in MI without hypoxemia
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Supplemental oxygen treatment did not reduce 1-year all-cause mortality in patients with suspected MI without hypoxemia, according to the results of the DETO2X-SWEDEDHEART study published in The New England Journal of Medicine.
“For more than a century, supplemental oxygen has been used routinely in the treatment of patients with suspected acute MI and is recommended in clinical guidelines,” Robin Hoffman, MD, from the department of clinical science and education and the department of clinical sciences at the Karolinska Institute, Södersjukuset, Sweden, and colleagues wrote. “However, above normal oxygen levels in the blood can cause coronary vasoconstriction and increase the production of reactive oxygen species, potentially contributing to reperfusion injury.”
To determine the clinical effect of routine oxygen therapy in this population, Hoffman and colleagues conducted a registry-based randomized clinical trial.
Researchers randomly assigned 6,629 patients with suspected MI and oxygen saturation levels of at least 90% to a regimen of either supplemental oxygen or ambient air.
According to the results of the study, the median duration of oxygen therapy was 11.6 hours, and at the end of the treatment period the median oxygen saturation was 99% among patients assigned to oxygen and 97% among patients assigned to ambient air (P < .001).
In the oxygen group, 1.9% developed hypoxemia, vs. 7.7% in the ambient-air group (P < .001).
The median of the highest troponin level during hospitalization was 946.5 ng/L in the oxygen and 983 ng/L in the ambient-air group.
Within 1 year of randomization, the primary endpoint of death from any cause occurred in 5% of patients assigned to oxygen and in 5.1% of patients assigned to ambient air (HR =0.97; 95% CI, 0.79-1.21).
Rehospitalization for MI within 1 year occurred in 3.8% of patients in the oxygen group and in 3.3% of patients assigned ambient air (HR = 1.13; 95% CI, 0.88-1.46).
The researchers found similar results in all predefined study groups.
In a related editorial, Joseph Loscalzo, MD, PhD, from the department of medicine, Brigham and Women’s Hospital, wrote that “Although the mechanisms underlying physiological and biochemical adaptation to myocardial ischemia are complex, the answer to the question is straightforward, and its implications for coronary care are indisputable: supplemental oxygen provides no benefit to patients with [ACS] who do not have hypoxemia. It is clearly time for clinical practice to change to reflect this definitive evidence.”
The findings were also presented at the European Society of Cardiology Congress. – by Dave Quaile
Disclosure: Hofmann and Loscalzo report they have no relevant financial disclosures. Please see the full study for a list of the other authors’ relevant financial disclosures.
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