Oxygen therapy in suspected acute myocardial infarction and concurrent normoxemic chronic obstructive pulmonary disease: a prespecified subgroup analysis from the DETO2X-AMI trial

Background: The DETermination of the role of Oxygen in suspected Acute Myocardial Infarction (DETO2X-AMI) trial did not find any benefit of oxygen therapy compared to ambient air in normoxemic patients with suspected acute myocardial infarction. Patients with chronic obstructive pulmonary disease may both benefit and be harmed by supplemental oxygen. Thus we evaluated the effect of routine oxygen therapy compared to ambient air in normoxemic chronic obstructive pulmonary disease patients with suspected acute myocardial infarction. Methods and results: A total of 6629 patients with suspected acute myocardial infarction were randomly assigned in the DETO2X-AMI trial to oxygen or ambient air. In the oxygen group (n=3311) and the ambient air group (n=3318), 155 and 141 patients, respectively, had chronic obstructive pulmonary disease (prevalence of 4.5%). Patients with chronic obstructive pulmonary disease were older, had more comorbid conditions and experienced a twofold higher risk of death at one year (chronic obstructive pulmonary disease: 32/296 (10.8%) vs. non-chronic obstructive pulmonary disease: 302/6333 (4.8%)). Oxygen therapy compared to ambient air was not associated with improved outcomes at 365 days (chronic obstructive pulmonary disease: all-cause mortality hazard ratio (HR) 0.99, 95% confidence interval (CI) 0.50–1.99, Pinteraction=0.96); cardiovascular death HR 0.80, 95% CI 0.32–2.04, Pinteraction=0.59); rehospitalisation with acute myocardial infarction or death HR 1.27, 95% CI 0.71–2.28, Pinteraction=0.46); hospitalisation for heart failure or death HR 1.08, 95% CI 0.61–1.91, Pinteraction=0.77]); there were no significant treatment-by-chronic obstructive pulmonary disease interactions. Conclusions: Although chronic obstructive pulmonary disease patients had twice the mortality rate compared to non-chronic obstructive pulmonary disease patients, this prespecified subgroup analysis from the DETO2X-AMI trial on oxygen therapy versus ambient air in normoxemic chronic obstructive pulmonary disease patients with suspected acute myocardial infarction revealed no evidence for benefit of routine oxygen therapy consistent with the main trial’s findings. Clinical Trials Registration: NCT02290080