No significant difference was observed in 30-day mortality for a "high" and a "low" oxygen protocol used as part of routine care in patients presenting with a suspected acute coronary syndrome (ACS), according to results from the NZOACS study presented Sept. 1 at ESC Congress 2019.

The two-year study out of New Zealand randomized 40,872 patients with suspected ACS (42 percent women) to either a high oxygen protocol (20,304) or a low oxygen protocol (20,568). Overall results found 30-day mortality for all patients with suspected ACS was 613 (3.02 percent) in the high oxygen protocol group compared with 642 (3.12 percent) in the low oxygen group (odds ratio [OR], 0.97).

When broken down by final diagnosis, 30-day mortality in the high oxygen protocol vs. low oxygen protocol groups for deaths not caused by ACS was 174 patients vs. 175 patients (OR, 1.01); for NSTEMI was 187 patients vs. 176 patients (OR, 1.05); and for STEMI deaths was 178 patients vs. 225 patients (OR, 0.81).

Additionally, researchers noted that high oxygen was unlikely to benefit patients with Sp02 ≥95 percent. "The study could not confirm or exclude a modest mortality benefit from high flow oxygen in patients with Sp02 <95 percent or ST elevation myocardial infarction," they said.

The liberal oxygen strategy seemed beneficial in the subgroup of patients with STEMI. "This finding if correct would be important, but its significance may be argued because this analysis was not the primary outcome for the study," said principal investigator and presenter Ralph Stewart, MB ChB, PhD.

Clinical Topics: Acute Coronary Syndromes, Invasive Cardiovascular Angiography and Intervention, Interventions and ACS, Interventions and Imaging, Angiography, Nuclear Imaging

Keywords: ESC 19, ESC Congress, Acute Coronary Syndrome, Angiography, Percutaneous Coronary Intervention

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