Beta-Blockers after Myocardial Infarction and Preserved Ejection Fraction.

BACKGROUND: Most trials that have shown a benefit of beta-blocker treatment after myocardial infarction included patients with large myocardial infarctions and were conducted in an era before modern biomarker-based diagnosis of myocardial infarction and treatment with percutaneous coronary intervention, antithrombotic agents, high-intensity statins, and renin-angiotensin-aldosterone system antagonists. METHODS: In a parallel-group, open-label trial performed at 45 centers in Sweden, Estonia, and New Zealand, we randomly assigned patients with an acute myocardial infarction who had undergone coronary angiography and had a left ventricular ejection fraction of at least 50% to receive either long-term treatment with a beta-blocker (metoprolol or bisoprolol) or no beta-blocker treatment. The primary end point was a composite of death from any cause or new myocardial infarction. RESULTS: From September 2017 through May 2023, a total of 5020 patients were enrolled (95.4% of whom were from Sweden). The median follow-up was 3.5 years (interquartile range, 2.2 to 4.7). A primary end-point event occurred in 199 of 2508 patients (7.9%) in the beta-blocker group and in 208 of 2512 patients (8.3%) in the no-beta-blocker group (hazard ratio, 0.96; 95% confidence interval, 0.79 to 1.16; P = 0.64). Beta-blocker treatment did not appear to lead to a lower cumulative incidence of the secondary end points (death from any cause, 3.9% in the beta-blocker group and 4.1% in the no-beta-blocker group; death from cardiovascular causes, 1.5% and 1.3%, respectively; myocardial infarction, 4.5% and 4.7%; hospitalization for atrial fibrillation, 1.1% and 1.4%; and hospitalization for heart failure, 0.8% and 0.9%). With regard to safety end points, hospitalization for bradycardia, second- or third-degree atrioventricular block, hypotension, syncope, or implantation of a pacemaker occurred in 3.4% of the patients in the beta-blocker group and in 3.2% of those in the no-beta-blocker group; hospitalization for asthma or chronic obstructive pulmonary disease in 0.6% and 0.6%, respectively; and hospitalization for stroke in 1.4% and 1.8%. CONCLUSIONS: Among patients with acute myocardial infarction who underwent early coronary angiography and had a preserved left ventricular ejection fraction (≥50%), long-term beta-blocker treatment did not lead to a lower risk of the composite primary end point of death from any cause or new myocardial infarction than no beta-blocker use. (Funded by the Swedish Research Council and others; REDUCE-AMI ClinicalTrials.gov number, NCT03278509.).

Excess Mortality and Loss of Life Expectancy After Myocardial Infarction: A Registry-Based Matched Cohort Study.

BACKGROUND: The effect of myocardial infarction (MI) on life expectancy is difficult to study because the prevalence of MI hinders direct comparison with the life expectancy of the general population. We sought to assess this in relation to age, sex, and left ventricular ejection fraction (LVEF) by comparing individuals with MI with matched comparators without previous MI. METHODS: We included patients with a first MI between 1991 and 2022 from the nationwide SWEDEHEART registry (Swedish Web-System for Enhancement and Development of Evidence-Based Care in Heart Disease Evaluated According to Recommended Therapies), each matched with up to 5 comparators on age, sex, and region of residence. Flexible parametric survival models were used to estimate excess mortality risk and mean loss of life expectancy (LOLE) depending on index year, age, sex, and LVEF, and adjusted for differences in characteristics. RESULTS: A total of 335 748 cases were matched to 1 625 396 comparators. A higher LOLE was observed in younger individuals, women, and those with reduced LVEF (<50%). In 2022, the unadjusted and adjusted mean LOLE spanned from 11.1 and 9.5 years in 50-year-old women with reduced LVEF to 5 and 3.7 months in 80-year-old men with preserved LVEF. Between 1992 and 2022, the adjusted mean LOLE decreased by 36% to 55%: from 4.4 to 2.0 years and from 3.3 to 1.9 years in 50-year-old women and men, respectively, and from 1.7 to 1.0 years and from 1.4 to 0.9 years in 80-year-old women and men, respectively. CONCLUSIONS: LOLE is higher in younger individuals, women, and those with reduced LVEF, but is attenuated when adjusting for comorbidities and risk factors. Advances in MI treatment during the past 30 years have almost halved LOLE, with no clear sign of leveling off to a plateau.

Prospective benchmarking of an observational analysis in the SWEDEHEART registry against the REDUCE-AMI randomized trial.

Prospective benchmarking of an observational analysis against a randomized trial increases confidence in the benchmarking process as it relies exclusively on aligning the protocol of the trial and the observational analysis, while the trials findings are unavailable. The Randomized Evaluation of Decreased Usage of Betablockers After Myocardial Infarction (REDUCE-AMI, ClinicalTrials.gov ID: NCT03278509) trial started recruitment in September 2017 and results are expected in 2024. REDUCE-AMI aimed to estimate the effect of long-term use of beta blockers on the risk of death and myocardial following a myocardial infarction with preserved left ventricular systolic ejection fraction. We specified the protocol of a target trial as similar as possible to that of REDUCE-AMI, then emulated the target trial using observational data from Swedish healthcare registries. Had everyone followed the treatment strategy as specified in the target trial protocol, the observational analysis estimated a reduction in the 5-year risk of death or myocardial infarction of 0.8 percentage points for beta blockers compared with no beta blockers; effects ranging from an absolute reduction of 4.5 percentage points to an increase of 2.8 percentage points in the risk of death or myocardial infarction were compatible with our data under conventional statistical criteria. Once results of REDUCE-AMI are published, we will compare the results of our observational analysis against those from the trial. If this prospective benchmarking is successful, it supports the credibility of additional analyses using these observational data, which can rapidly deliver answers to questions that could not be answered by the initial trial. If benchmarking proves unsuccessful, we will conduct a "postmortem" analysis to identify the reasons for the discrepancy. Prospective benchmarking shifts the investigator focus away from an endeavour to use observational data to obtain similar results as a completed randomized trial, to a systematic attempt to align the design and analysis of the trial and the observational analysis.

Long-term antithrombotic therapy after coronary artery bypass grafting in patients with preoperative atrial fibrillation. A nationwide observational study from the SWEDEHEART registry.

AIMS: To provide data guiding long-term antithrombotic therapy after coronary artery by-pass grafting (CABG) in patients with preoperative atrial fibrillation (AF). METHODS AND RESULTS: From the SWEDEHEART registry, we included all patients, between January 2006 and September 2016, with preoperative AF and CHA2DS2-VASC score ≥2, undergoing CABG. Based on dispensed prescriptions 12 to 18 months after CABG, patients were divided in 3 groups: use of platelet inhibitors (PI) only, oral anticoagulant (OAC) only or a combination of OAC + PI. Outcomes were: Major adverse cardiac and cerebrovascular events (MACCE, [all-cause death, myocardial infarction, or stroke]), net adverse clinical events (NACE, [MACCE or bleeding]) and the individual components of NACE. Inverse probability of treatment weighting was used to adjust for the non-randomized study design. Among 2,564 patients, 1,040 (41%) were treated with PI alone, 1,064 (41%) with OAC alone, and 460 (18%) with PI + OAC. Treatment with PI alone was associated with higher risk for MACCE (adjusted HR 1.43, 95% CI 1.09-1.88), driven by higher risk for stroke and MI, compared with OAC alone. Treatment with PI + OAC, was associated with higher risk for NACE (adjusted HR 1.40, 95% CI 1.06-1.85), driven by higher risk for bleeds, compared with OAC alone. CONCLUSION: In this real-world observational study, a high proportion of patients with AF, undergoing CABG, did not receive a long-term OAC therapy. Treatment with OAC alone was associated with a net clinical benefit, compared with PI alone or PI + OAC.

Hyperoxemia after reperfusion in cardiac arrest patients: a potential dose-response association with 30-day survival.

BACKGROUND: Hyperoxemia may aggravate reperfusion brain injury after cardiac arrest. The aim of this study was to study the associations between different levels of hyperoxemia in the reperfusion period after cardiac arrest and 30-day survival. METHODS: Nationwide observational study using data from four compulsory Swedish registries. Adult in- and out-of-hospital cardiac arrest patients admitted to an ICU, requiring mechanical ventilation, between January 2010 and March 2021, were included. The partial oxygen pressure (PaO2) was collected in a standardized way at ICU admission (± one hour) according to the simplified acute physiology score 3 reflecting the time interval with oxygen treatment from return of spontaneous circulation to ICU admission. Subsequently, patients were divided into groups based on the registered PaO2 at ICU admission. Hyperoxemia was categorized into mild (13.4-20 kPa), moderate (20.1-30 kPa) severe (30.1-40 kPa) and extreme (> 40 kPa), and normoxemia as PaO2 8-13.3 kPa. Hypoxemia was defined as PaO2 < 8 kPa. Primary outcome was 30-day survival and relative risks (RR) were estimated by multivariable modified Poisson regression. RESULTS: In total, 9735 patients were included of which 4344 (44.6%) were hyperoxemic at ICU admission. Among these, 2217 were classified as mild, 1091 as moderate, 507 as severe, and 529 as extreme hyperoxemia. Normoxemia was present in 4366 (44.8%) patients and 1025 (10.5%) had hypoxemia. Compared to the normoxemia group, the adjusted RR for 30-day survival in the whole hyperoxemia group was 0.87 (95% CI 0.82-0.91). The corresponding results for the different hyperoxemia subgroups were; mild 0.91 (95% CI 0.85-0.97), moderate 0.88 (95% CI 0.82-0.95), severe 0.79 (95% CI 0.7-0.89), and extreme 0.68 (95% CI 0.58-0.79). Adjusted 30-day survival for the hypoxemia compared to normoxemia group was 0.83 (95% CI 0.74-0.92). Similar associations were seen in both out-of-hospital and in-hospital cardiac arrests. CONCLUSION: In this nationwide observational study comprising both in- and out-of-hospital cardiac arrest patients, hyperoxemia at ICU admission was associated with lower 30-day survival.

Helicobacter Pylori Virulence Factor Cytotoxin-Associated Gene A (CagA) Induces Vascular Calcification in Coronary Artery Smooth Muscle Cells.

Helicobacter pylori (H. pylori) has been associated with cardiovascular diseases. The pro-inflammatory H. pylori virulence factor cytotoxin-associated gene A (CagA) has been detected in serum exosomes of H. pylori-infected subjects and may exert systemic effects throughout the cardiovascular system. The role of H. pylori and CagA in vascular calcification was hitherto unknown. The aim of this study was to determine the vascular effects of CagA through human coronary artery smooth muscle cell (CASMC) osteogenic and pro-inflammatory effector gene expression as well as interleukin 1ß secretion and cellular calcification. CagA upregulated bone morphogenic protein 2 (BMP-2) associated with an osteogenic CASMC phenotype switch and induced increased cellular calcification. Furthermore, a pro-inflammatory response was observed. These results support that H. pylori may contribute to vascular calcification through CagA rendering CASMCs osteogenic and inducing calcification.

Helicobacter pylori and Pro-Inflammatory Protein Biomarkers in Myocardial Infarction with and without Obstructive Coronary Artery Disease.

Myocardial infarction (MI) with obstructive coronary artery disease (MI-CAD) and MI in the absence of obstructive coronary artery disease (MINOCA) affect different populations and may have separate pathophysiological mechanisms, with greater inflammatory activity in MINOCA compared to MI-CAD. Helicobacter pylori (Hp) can cause systemic inflammation and has been associated with cardiovascular disease (CVD). We aimed to investigate whether Hp infection is associated with concentrations of protein biomarkers of inflammation and CVD. In a case-control study, patients with MINOCA (n = 99) in Sweden were included, complemented by matched subjects with MI-CAD (n = 99) and controls (n = 100). Protein biomarkers were measured with a proximity extension assay in plasma samples collected 3 months after MI. The seroprevalence of Hp and cytotoxin-associated gene A (CagA) was determined using ELISA. The associations between protein levels and Hp status were studied with linear regression. The prevalence of Hp was 20.2%, 19.2%, and 16.0% for MINOCA, MI-CAD, and controls, respectively (p = 0.73). Seven proteins were associated with Hp in an adjusted model: tissue plasminogen activator (tPA), interleukin-6 (IL-6), myeloperoxidase (MPO), TNF-related activation-induced cytokine (TRANCE), pappalysin-1 (PAPPA), soluble urokinase plasminogen activator receptor (suPAR), and P-selectin glycoprotein ligand 1 (PSGL-1). Hp infection was present in one in five patients with MI, irrespective of the presence of obstructive CAD. Inflammatory proteins were elevated in Hp-positive subjects, thus not ruling out that Hp may promote an inflammatory response and potentially contribute to the development of CVD.

Association of Metabolic Surgery With Major Adverse Cardiovascular Outcomes in Patients With Previous Myocardial Infarction and Severe Obesity: A Nationwide Cohort Study.

BACKGROUND: The number of patients with myocardial infarction and severe obesity is increasing and there is a lack of evidence how these patients should be treated. The aim of this study was to investigate the association between metabolic surgery (Roux-en-Y gastric bypass and sleeve gastrectomy) and major adverse cardiovascular events in patients with previous myocardial infarction (MI) and severe obesity. METHODS: Of 566 patients with previous MI registered in the SWEDEHEART registry (Swedish Web-System for Enhancement and Development of Evidence-Based Care in Heart Disease Evaluated According to Recommended Therapies) undergoing metabolic surgery and registered in the nationwide Scandinavian Obesity Surgery Registry, 509 patients (Roux-en-Y gastric bypass n=465; sleeve gastrectomy n=44) could be matched 1:1 to a control with MI from SWEDEHEART, but no subsequent metabolic surgery regarding sex, age (±3 years), year of MI (±3 years), and body mass index (±3). The 2 groups were well matched, except for a lower proportion of reduced ejection fraction after MI (7% versus 12%), previous heart failure (10% versus 19%), atrial fibrillation (6% versus 10%), and chronic obstructive pulmonary disease (4% versus 7%) in patients undergoing metabolic surgery. RESULTS: The median (interquartile range) follow-up time was 4.6 (2.7-7.1) years. The 8-year cumulative probability of major adverse cardiovascular events was lower in patients undergoing metabolic surgery (18.7% [95% CI, 15.9-21.5%] versus 36.2% [33.2-39.3%], adjusted hazard ratio, 0.44 [95% CI, 0.32-0.61]). Patients undergoing metabolic surgery had also a lower risk of death (adjusted HR, 0.45 [95% CI, 0.29-0.70]; MI, 0.24 [0.14-0.41]) and new onset heart failure, but there were no significant differences regarding stroke (0.91 [0.38-2.20]) and new onset atrial fibrillation (0.56 [0.31-1.01]). CONCLUSIONS: In severely obese patients with previous MI, metabolic surgery is associated with a low risk for serious complications, lower risk of major adverse cardiovascular events, death, new MI, and new onset heart failure. These findings need to be confirmed in a randomized, controlled trial.

Long-term mortality in patients with ischaemic heart failure revascularized with coronary artery bypass grafting or percutaneous coronary intervention: insights from the Swedish Coronary Angiography and Angioplasty Registry (SCAAR).

AIMS: To compare coronary artery bypass grafting (CABG) and percutaneous coronary intervention (PCI) for treatment of patients with heart failure due to ischaemic heart disease. METHODS AND RESULTS: We analysed all-cause mortality following CABG or PCI in patients with heart failure with reduced ejection fraction and multivessel disease (coronary artery stenosis >50% in ≥2 vessels or left main) who underwent coronary angiography between 2000 and 2018 in Sweden. We used a propensity score-adjusted logistic and Cox proportional-hazards regressions and instrumental variable model to adjust for known and unknown confounders. Multilevel modelling was used to adjust for the clustering of observations in a hierarchical database. In total, 2509 patients (82.9% men) were included; 35.8% had diabetes and 34.7% had a previous myocardial infarction. The mean age was 68.1 ± 9.4 years (47.8% were >70 years old), and 64.9% had three-vessel or left main disease. Primary designated therapy was PCI in 56.2% and CABG in 43.8%. Median follow-up time was 3.9 years (range 1 day to 10 years). There were 1010 deaths. Risk of death was lower after CABG than after PCI [odds ratio (OR) 0.62; 95% confidence interval (CI) 0.41-0.96; P = 0.031]. The risk of death increased linearly with quintiles of hospitals in which PCI was the preferred method for revascularization (OR 1.27, 95% CI 1.17-1.38, Ptrend < 0.001). CONCLUSION: In patients with ischaemic heart failure, long-term survival was greater after CABG than after PCI.

Comparison Between Ticagrelor and Clopidogrel in Elderly Patients With an Acute Coronary Syndrome: Insights From the SWEDEHEART Registry.

BACKGROUND: The comparative efficacy and safety of ticagrelor versus clopidogrel in older patients with myocardial infarction (MI) has received limited study. METHODS: We performed an observational analysis of all patients ≥80 years (n=14 005) who were discharged alive with aspirin combined with either clopidogrel (60.2%) or ticagrelor (39.8%) after a MI between 2010 and 2017 registered in the national registry SWEDEHEART (Swedish Web-System for Enhancement and Development of Evidence-Based Care in Heart Disease Evaluated According to Recommended Therapies). Inverse probability treatment weighting was used in Cox regression models to adjust for differences in demographics, in-hospital therapies, and medications. The primary ischemic outcome (death, MI, or stroke), and bleeding were obtained from national registries at 1 year. A sensitivity analysis in <80-year-old patients was performed. RESULTS: In patients ≥80 years, the incidence of the primary ischemic outcome (hazard ratio [HR], 0.97 [95% CI, 0.88-1.06]) was similar for ticagrelor- and clopidogrel-treated patients. Ticagrelor was associated with a 17% and 48% higher risk of death (HR, 1.17 [95% CI, 1.03-1.32]) and bleeding (HR, 1.48 [95% CI, 1.25-1.76]), but a lower risk of MI (HR, 0.80 [95% CI, 0.70-0.92]) and stroke (HR, 0.72 [95% CI, 0.56-0.93]). In <80-year-old patients, the incidence of the primary ischemic outcome was 17% (HR, 0.83 [95% CI, 0.77-0.89]) lower with ticagrelor. Ticagrelor was associated with 15% (HR, 0.85 [95% CI, 0.76-0.96]) lower risk of death, 32% higher risk of bleeding (HR, 1.32 [95% CI, 1.18-1.47]), but lower risk of MI (HR, 0.82 [95% CI, 0.75-0.91]) and stroke (HR, 0.82 [95% CI, 0.69-0.98]). CONCLUSIONS: Ticagrelor use among elderly patients with MI was associated with higher risk of bleeding and death compared with clopidogrel. A randomized study of ticagrelor versus clopidogrel in the elderly is needed.

Helicobacter pylori screening in clinical routine during hospitalization for acute myocardial infarction.

BACKGROUND: Potent antithrombotic therapy has significantly improved prognosis for patients with acute myocardial infarction (AMI), however, at a price of increased bleeding risk. Chronic gastric infection with Helicobacter pylori (Hp) commonly causes upper gastrointestinal bleeding and is proposed as a risk factor for subsequent bleeding post AMI. The prevalence of active Hp in a current AMI population and the feasibility of Hp screening as part of routine clinical care are unclear. OBJECTIVE: To determine the prevalence of active Hp infection in a contemporary AMI cohort and to establish the feasibility of Hp diagnosis as part of routine clinical MI care. DESIGN: Multicenter, prospective cohort study. SETTING: Two university hospitals in Stockholm, Sweden. PARTICIPANTS: Patients admitted for AMI between November 6, 2019 and April 4, 2020. After written informed consent, Hp diagnostics was performed with a bedside urea breath test (Diabact, Mayoly Spindler) incorporated into routine care during the hospitalization period. EXPOSURE: Positive test for Hp infection. MAIN OUTCOMES AND MEASURES: The primary outcome was the prevalence of Hp infection. Secondary aims included predictive factors in patient characteristics and outcomes which were obtained from linkage with national registries. Predefined subgroup analyses included stratification for proton pump inhibitor use and infarct type. RESULTS: Three hundred and ten consecutive AMI patients (median age 67; 23% female; 41% ST-elevation MI [STEMI]) were enrolled. Overall, the Hp prevalence was 20% (95%CI, 15.5-24.7). Hp positive status was significantly more common in smokers compared with nonsmokers (36% vs 21%, respectively; P < .05) and in patients presenting with STEMI compared with Non-STEMI (26% vs 15%, respectively; P = .02). The latter observation remained significant after multivariable adjustment. After exclusion of 97 subjects with current proton pump inhibitor use, the Hp prevalence was 24% (95%CI, 18.9-31.0). CONCLUSIONS: Active Hp infection is common in a contemporary AMI population and may represent a modifiable risk factor for upper gastrointestinal bleeding, which has been hitherto disregarded. Hp screening as part of clinical routine during AMI hospitalization was feasible. A future randomized trial is needed to determine whether routine Hp screening and subsequent eradication therapy reduces bleeding complications and improves prognosis. KEY POINTS: Question: Is Helicobacter pylori (Hp) infection sufficiently common in patients with acute myocardial infarction (AMI) to consider systematic screening, and can Hp diagnostics be performed during AMI hospitalization? FINDINGS: In this multicenter prospective cohort study of 310 consecutive AMI patients, Hp infection was established in at least 20% of patients. Infected patients were significantly more likely to be active smokers and to present with ST-elevation MI. Meaning: Hp screening as part of clinical routine during AMI hospitalization was feasible. Given the high Hp prevalence detected, Hp diagnostics and eradication to reduce bleeding complications and to improve prognosis after AMI should be further investigated.

Randomized comparison of early supplemental oxygen versus ambient air in patients with confirmed myocardial infarction: Sex-related outcomes from DETO2X-AMI.

BACKGROUND: The purpose of this study is to investigate the impact of oxygen therapy on cardiovascular outcomes in relation to sex in patients with confirmed myocardial infarction (MI). METHODS: The DETermination of the role of Oxygen in suspected Acute Myocardial Infarction trial randomized 6,629 patients to oxygen at 6 L/min for 6-12 hours or ambient air. In the present subgroup analysis including 5,010 patients (1,388 women and 3,622 men) with confirmed MI, we report the effect of supplemental oxygen on the composite of all-cause death, rehospitalization with MI, or heart failure at long-term follow-up, stratified according to sex. RESULTS: Event rate for the composite endpoint was 18.1% in women allocated to oxygen, compared to 21.4% in women allocated to ambient air (hazard ratio [HR] 0.83, 95% confidence interval [CI] 0.65-1.05). In men, the incidence was 13.6% in patients allocated to oxygen compared to 13.3% in patients allocated to ambient air (HR 1.03, 95% CI 0.86-1.23). No significant interaction in relation to sex was found (P= .16). Irrespective of allocated treatment, the composite endpoint occurred more often in women compared to men (19.7 vs 13.4%, HR 1.51; 95% CI, 1.30-1.75). After adjustment for age alone, there was no difference between the sexes (HR 1.06, 95% CI 0.91-1.24), which remained consistent after multivariate adjustment. CONCLUSION: Oxygen therapy in normoxemic MI patients did not significantly affect all-cause mortality or rehospitalization for MI or heart failure in women or men. The observed worse outcome in women was explained by differences in baseline characteristics, especially age.

Temporal trends in bleeding events in acute myocardial infarction: insights from the SWEDEHEART registry.

AIMS: To describe the time trends of in-hospital and out-of-hospital bleeding parallel to the development of new treatments and ischaemic outcomes over the last 20 years in a nationwide myocardial infarction (MI) population. METHODS AND RESULTS: Patients with acute MI (n = 371 431) enrolled in the SWEDEHEART registry from 1995 until May 2018 were selected and evaluated for in-hospital bleeding and out-of-hospital bleeding events at 1 year. In-hospital bleeding increased from 0.5% to a peak at 2% 2005/2006 and thereafter slightly decreased to a new plateau around 1.3% by the end of the study period. Out-of-hospital bleeding increased in a stepwise fashion from 2.5% to 3.5 % in the middle of the study period and to 4.8% at the end of the study period. The increase in both in-hospital and out-of-hospital bleeding was parallel to increasing use of invasive strategy and adjunctive antithrombotic treatment, dual antiplatelet therapy (DAPT), and potent DAPT, while the decrease in in-hospital bleeding from 2007 to 2010 was parallel to implementation of bleeding avoidance strategies. In-hospital re-infarction decreased from 2.8% to 0.6% and out-of-hospital MI decreased from 12.6% to 7.1%. The composite out-of-hospital MI, cardiovascular death, and stroke decreased in a similar fashion from 18.4% to 9.1%. CONCLUSION: During the last 20 years, the introduction of invasive and more intense antithrombotic treatment has been associated with an increase in bleeding events but concomitant there has been a substantial greater reduction of ischaemic events including improved survival.

Oxygen Therapy in Suspected Acute Myocardial Infarction.

BACKGROUND: The clinical effect of routine oxygen therapy in patients with suspected acute myocardial infarction who do not have hypoxemia at baseline is uncertain. METHODS: In this registry-based randomized clinical trial, we used nationwide Swedish registries for patient enrollment and data collection. Patients with suspected myocardial infarction and an oxygen saturation of 90% or higher were randomly assigned to receive either supplemental oxygen (6 liters per minute for 6 to 12 hours, delivered through an open face mask) or ambient air. RESULTS: A total of 6629 patients were enrolled. The median duration of oxygen therapy was 11.6 hours, and the median oxygen saturation at the end of the treatment period was 99% among patients assigned to oxygen and 97% among patients assigned to ambient air. Hypoxemia developed in 62 patients (1.9%) in the oxygen group, as compared with 254 patients (7.7%) in the ambient-air group. The median of the highest troponin level during hospitalization was 946.5 ng per liter in the oxygen group and 983.0 ng per liter in the ambient-air group. The primary end point of death from any cause within 1 year after randomization occurred in 5.0% of patients (166 of 3311) assigned to oxygen and in 5.1% of patients (168 of 3318) assigned to ambient air (hazard ratio, 0.97; 95% confidence interval [CI], 0.79 to 1.21; P=0.80). Rehospitalization with myocardial infarction within 1 year occurred in 126 patients (3.8%) assigned to oxygen and in 111 patients (3.3%) assigned to ambient air (hazard ratio, 1.13; 95% CI, 0.88 to 1.46; P=0.33). The results were consistent across all predefined subgroups. CONCLUSIONS: Routine use of supplemental oxygen in patients with suspected myocardial infarction who did not have hypoxemia was not found to reduce 1-year all-cause mortality. (Funded by the Swedish Heart-Lung Foundation and others; DETO2X-AMI ClinicalTrials.gov number, NCT01787110 .).

Long-Term Effects of Oxygen Therapy on Death or Hospitalization for Heart Failure in Patients With Suspected Acute Myocardial Infarction

Background: In the DETO2X-AMI trial (Determination of the Role of Oxygen in Suspected Acute Myocardial Infarction), we compared supplemental oxygen with ambient air in normoxemic patients presenting with suspected myocardial infarction and found no significant survival benefit at 1 year. However, important secondary end points were not yet available. We now report the prespecified secondary end points cardiovascular death and the composite of all-cause death and hospitalization for heart failure. Methods: In this pragmatic, registry-based randomized clinical trial, we used a nationwide quality registry for coronary care for trial procedures and evaluated end points through the Swedish population registry (mortality), the Swedish inpatient registry (heart failure), and cause of death registry (cardiovascular death). Patients with suspected acute myocardial infarction and oxygen saturation of ≥90% were randomly assigned to receive either supplemental oxygen at 6 L/min for 6 to 12 hours delivered by open face mask or ambient air. Results: A total of 6629 patients were enrolled. Acute heart failure treatment, left ventricular systolic function assessed by echocardiography, and infarct size measured by high-sensitive cardiac troponin T were similar in the 2 groups during the hospitalization period. All-cause death or hospitalization for heart failure within 1 year after randomization occurred in 8.0% of patients assigned to oxygen and in 7.9% of patients assigned to ambient air (hazard ratio, 0.99; 95% CI, 0.84­1.18; P=0.92). During long-term follow-up (median [range], 2.1 [1.0­3.7] years), the composite end point occurred in 11.2% of patients assigned to oxygen and in 10.8% of patients assigned to ambient air (hazard ratio, 1.02; 95% CI, 0.88­1.17; P=0.84), and cardiovascular death occurred in 5.2% of patients assigned to oxygen and in 4.8% assigned to ambient air (hazard ratio, 1.07; 95% CI, 0.87­1.33; P=0.52). The results were consistent across all predefined subgroups. Conclusions: Routine use of supplemental oxygen in normoxemic patients with suspected myocardial infarction was not found to reduce the composite of all-cause mortality and hospitalization for heart failure, or cardiovascular death within 1 year or during long-term follow-up. Clinical Trial Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT01787110.

Oxygen therapy in ST-elevation myocardial infarction.

Aims: To determine whether supplemental oxygen in patients with ST-elevation myocardial infarction (STEMI) impacts on procedure-related and clinical outcomes. Methods and results: The DETermination of the role of Oxygen in suspected Acute Myocardial Infarction (DETO2X-AMI) trial randomized patients with suspected myocardial infarction (MI) to receive oxygen at 6 L/min for 6-12 h or ambient air. In this pre-specified analysis, we included only STEMI patients who underwent percutaneous coronary intervention (PCI). In total, 2807 patients were included, 1361 assigned to receive oxygen, and 1446 assigned to ambient air. The pre-specified primary composite endpoint of all-cause death, rehospitalization with MI, cardiogenic shock, or stent thrombosis at 1 year occurred in 6.3% (86 of 1361) of patients allocated to oxygen compared to 7.5% (108 of 1446) allocated to ambient air [hazard ratio (HR) 0.85, 95% confidence interval (95% CI) 0.64-1.13; P = 0.27]. There was no difference in the rate of death from any cause (HR 0.86, 95% CI 0.61-1.22; P = 0.41), rate of rehospitalization for MI (HR 0.92, 95% CI 0.57-1.48; P = 0.73), rehospitalization for cardiogenic shock (HR 1.05, 95% CI 0.21-5.22; P = 0.95), or stent thrombosis (HR 1.27, 95% CI 0.46-3.51; P = 0.64). The primary composite endpoint was consistent across all subgroups, as well as at different time points, such as during hospital stay, at 30 days and the total duration of follow-up up to 1356 days. Conclusions: Routine use of supplemental oxygen in normoxemic patients with STEMI undergoing primary PCI did not significantly affect 1-year all-cause death, rehospitalization with MI, cardiogenic shock, or stent thrombosis.