Background, study design and summary:
The use of supplemental oxygen in the setting of acute myocardial infarction as well as during percutanous coronary intervention (PCI) when diagnosing or treating stabile coronary disease is well established in pre-hospital and hospital clinical routine.
Current international treatment guidelines recommend the use of supplemental oxygen in the setting of suspected acute coronary syndrome (ACS) in case of hypoxia (oxygen saturation <90%, class I, B).
However, for normooxic patients with oxygen saturation ≥90%, recommendations are vague and inconsistent due to the lack of evidence based on randomized, controlled trials using current medical and reperfusion treatment strategies. This situation has been identified in a number of recently published scientific articles, which led to the consensus that a “definitive, large, randomized, controlled trial is urgently needed” to shed light on this important issue.
The recommendations above are based on the hypothesis that supplemental oxygen decreases infarct size due to increased oxygen delivery to ischemic areas in the myocardium. This approach is largely based on experimental laboratory data and small studies in humans mostly using high oxygen concentration or even hyperbaric surroundings or hyperoxemic reperfusion therapy. In contrast to this, emerging clinical data describes negative hemodynamic effects of high oxygen concentrations on coronary circulation. Additionally, recent studies examining the role of reactive oxygen species (ROS), suggest that in ischemia, ROS are a significant factor in post ischemic injury.
On the basis of apparently conflicting experimental and clinical data above, uncertainty over the utility of routine supplemental oxygen in the setting of suspected AMI remains. The DETO₂X-AMI study series is designed and powered to evaluate effects of oxygen in acute cardiac ischemia not only by looking at hard endpoints in an adequately powered RRCT but even by surrogate endpoints using modern biochemistry, angiographic and imaging techniques.
At ESC’s Acute Cardiac Care (ACCA) Congress in Genèva 2014 the background and study design was presented at an RRCT concept session chaired by Professor Tom Quinn and Professor Pascal Vranckx.