Background—: Oxygen is commonly administered to patients with ST-elevation–myocardial infarction despite previous studies suggesting a possible increase in myocardial injury as a result of coronary vasoconstriction and heightened oxidative stress. Methods and Results—: We conducted a multicenter, prospective, randomized, controlled trial comparing oxygen (8 L/min) with no supplemental oxygen in patients with ST-elevation–myocardial infarction diagnosed on paramedic 12-lead ECG. Of 638 patients randomized, 441 patients had confirmed ST-elevation–myocardial infarction and underwent primary end-point analysis. The primary end point was myocardial infarct size as assessed by cardiac enzymes, troponin I, and creatine kinase. Secondary end points included recurrent myocardial infarction, cardiac arrhythmia, and myocardial infarct size assessed by cardiac magnetic resonance imaging at 6 months. Mean peak troponin was similar in the oxygen and no oxygen groups (57.4 versus 48.0 μg/L; ratio, 1.20; 95% confidence interval, 0.92–1.56; P =0.18). There was a significant increase in mean peak creatine kinase in the oxygen group compared with the no oxygen group (1948 versus 1543 U/L; means ratio, 1.27; 95% confidence interval, 1.04–1.52; P =0.01). There was an increase in the rate of recurrent myocardial infarction in the oxygen group compared with the no oxygen group (5.5% versus 0.9%; P =0.006) and an increase in frequency of cardiac arrhythmia (40.4% versus 31.4%; P =0.05). At 6 months, the oxygen group had an increase in myocardial infarct size on cardiac magnetic resonance (n=139; 20.3 versus 13.1 g; P =0.04). Conclusion—: Supplemental oxygen therapy in patients with ST-elevation–myocardial infarction but without hypoxia may increase early myocardial injury and was associated with larger myocardial infarct size assessed at 6 months. Clinical Trial Registration—: URL: http://www.clinicaltrials.gov . Unique identifier: NCT01272713.

Background—: Out-of-hospital cardiac arrest (OHCA) is a significant global health problem. There has been considerable investment in improving the emergency medical response to OHCA, with associated improvements in survival. However, concern remains that survivors have a poor quality of life. This study describes the quality of life of OHCA survivors at 1-year postarrest in Victoria, Australia. Methods and Results—: Adult OHCA patients who arrested between 2010 and 2012 were identified from the Victorian Ambulance Cardiac Arrest Registry. Paramedics attended 15 113 OHCA patients of which 46.3% received an attempted resuscitation. Nine hundred and twenty-seven (13.2%) survived to hospital discharge of which 76 (8.2%) died within 12 months. Interviews were conducted with 697 (80.7%) patients or proxies, who were followed-up via telephone interview, including the Glasgow Outcome Scale–Extended, the 12-item short form health survey, and the EuroQol. The majority (55.6%) of respondents had a good recovery via the Glasgow Outcome Scale–Extended≥7 (41.1% if patients who died postdischarge were included and nonrespondents were assumed to have poor recovery). The mean EuroQol index score for respondents was 0.82 (standard deviation, 0.19), which compared favorably with an adjusted population norm of 0.81 (standard deviation, 0.34). The mean 12-item short form Mental Component Summary score for patients was 53.0 (standard deviation, 10.2), whereas the mean Physical Component Summary score was 46.1 (standard deviation, 11.2). Conclusions—: This is the largest published study assessing the quality of life of OHCA survivors. It provides good evidence that many survivors have an acceptable quality of life 12 months postarrest, particularly in comparison with population norms.

The aim of this study was to investigate regional variation in the characteristics, incidence and outcomes of out-of-hospital cardiac arrest (OHCA) in Australia and New Zealand. This was a population-based cohort study of OHCA using data from the Aus-ROC Australian and New Zealand OHCA Epistry over the period of 01 January 2015-31 December 2015. Seven ambulance services contributed data to the Epistry with a capture population of 19.8 million people. All OHCA attended by ambulance, regardless of aetiology or patient age, were included. In 2015, there were 19,722 OHCA cases recorded in the Aus-ROC Epistry with an overall crude incidence of 102.5 cases per 100,000 population (range: 51.0-107.7 per 100,000 population). Of all OHCA cases attended by EMS (excluding EMS-witnessed cases), bystander CPR was performed in 41% of cases (range: 36%-50%). Resuscitation was attempted (by EMS) in 48% of cases (range: 40%-68%). The crude incidence for attempted resuscitation cases was 47.6 per 100,000 population (range: 34.7-54.1 per 100,000 population). Of cases with attempted resuscitation, 28% survived the event (range: 21%-36%) and 12% survived to hospital discharge or 30 days (range: 9%-17%; data provided by five ambulance services). In the first results of the Aus-ROC Australian and New Zealand OHCA Epistry, significant regional variation in the incidence, characteristics and outcomes was observed. Understanding the system-level and public health drivers of this variation will assist in optimisation of the chain of survival provided to OHCA patients with the aim of improving outcomes.