Background: In Japan, oxygen is commonly administered during the acute phase of myocardial infarction (MI) to patients without oxygen saturation monitoring. In this study we assessed the effects of supplemental oxygen therapy, compared with ambient air, on mortality and cardiac events by synthesizing evidence from randomized controlled trials (RCTs) of patients with suspected or confirmed acute MI.

Methods and Results: PubMed was systematically searched for full-text RCTs published in English before June 21, 2020. Two reviewers independently screened the search results and appraised the risk of bias. The estimates for each outcome were pooled using a random-effects model. In all, 2,086 studies retrieved from PubMed were screened. Finally, 7,322 patients from 9 studies derived from 4 RCTs were analyzed. In-hospital mortality in the oxygen and ambient air groups was 1.8% and 1.6%, respectively (risk ratio [RR] 0.90; 95% confidence interval [CI] 0.38–2.10]); 0.8% and 0.5% of patients, respectively, experienced recurrent MI (RR 0.44; 95% CI 0.12–1.54), 1.5% and 1.6% of patients, respectively, experienced cardiac shock (RR 1.10; 95% CI 0.77–1.59]), and 2.4% and 2.0% of patients, respectively, experienced cardiac arrest (RR 0.91; 95% CI 0.43–1.94).

Conclusions: Routine supplemental oxygen administration may not be beneficial or harmful, and high-flow oxygen may be unnecessary in normoxic patients in the acute phase of MI.

Background: Recent guidelines for acute coronary syndrome (ACS) recommend prehospital administration of aspirin and nitroglycerin for ACS patients. However, there is no clear evidence to support this. We investigated the benefits and harms of prehospital administration of aspirin and nitroglycerin by non-physician healthcare professionals in patients with suspected ACS.

Methods and Results: We searched the PubMed database and used the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) approach to assess the certainty of evidence. Three retrospective studies for aspirin and 1 for nitroglycerin administered in the prehospital setting to patients with acute myocardial infarction were included. Prehospital aspirin administration was associated with significantly lower 30-day and 1-year mortality compared with aspirin administration after arrival at hospital, with odds ratios (OR) of 0.59 (95% confidence interval [CI] 0.35–0.99) and 0.47 (95% CI 0.36–0.62), respectively. Prehospital nitroglycerin administration was also associated with significantly lower 30-day and 1-year mortality compared with no prehospital administration (OR 0.34 [95% CI 0.24–0.50] and 0.38 [95% CI 0.29–0.50], respectively). The certainty of evidence was very low in both systematic reviews.

Conclusions: Our systematic reviews suggest that prehospital administration of aspirin and nitroglycerin by non-physician healthcare professionals is beneficial for patients with suspected ACS, although the certainty of evidence is very low. Further investigation is needed to determine the benefit of the prehospital administration of these agents.

Background: In the management of patients with ST-elevation myocardial infarction (STEMI), system delays for reperfusion therapy are still a matter of concern. We investigated the impact of prehospital activation of the catheterization laboratory in the management of STEMI patients.

Methods and Results: This is a systematic review of observational studies. A search was conducted of the PubMed database from inception to July 2020 to identify articles for inclusion in the study. The critical outcomes were short- and long-term mortality. The important outcome was door-to-balloon time. The GRADE approach was used to assess the certainty of the evidence. Seven studies assessed short-term mortality; 1,541 were assigned to the prehospital activation (PH) group and 1,191 were assigned to the emergency department activation (ED) group. There were 26 fewer deaths per 1,000 patients in the PH group. Three studies assessed long-term mortality; 713 patients were assigned to the PH group and 1,026 were assigned to the ED group. There were 54 fewer deaths per 1,000 patients among the PH group. Five studies assessed door-to-balloon time; 959 were assigned to the PH group and 631 to the ED group. Door-to-balloon time was 33.1 min shorter in the PH group.

Conclusions: Prehospital activation of the catheterization laboratory resulted in lower mortality and shorter door-to-balloon time for patients with suspected STEMI outside of a hospital.

Background: The aim of this study was to assess and discuss the diagnostic accuracy of prehospital ECG interpretation through systematic review and meta-analyses.

Methods and Results: Relevant literature published up to July 2020 was identified using PubMed. All human studies of prehospital adult patients suspected of ST-segment elevation myocardial infarction in which prehospital electrocardiogram (ECG) interpretation by paramedics or computers was evaluated and reporting all 4 (true-positive, false-positive, false-negative, and true-negative) values were included. Meta-analyses were conducted separately for the diagnostic accuracy of prehospital ECG interpretation by paramedics (Clinical Question [CQ] 1) and computers (CQ2). After screening, 4 studies for CQ1 and 6 studies for CQ2 were finally included in the meta-analysis. Regarding CQ1, the pooled sensitivity and specificity were 95.5% (95% confidence interval [CI] 82.5–99.0%) and 95.8% (95% CI 82.3–99.1%), respectively. Regarding CQ2, the pooled sensitivity and specificity were 85.4% (95% CI 74.1–92.3%) and 95.4% (95% CI 87.3–98.4%), respectively.

Conclusions: This meta-analysis suggests that the diagnostic accuracy of paramedic prehospital ECG interpretations is favorable, with high pooled sensitivity and specificity, with an acceptable estimated number of false positives and false negatives. Computer-assisted ECG interpretation showed high pooled specificity with an acceptable estimated number of false positives, whereas the pooled sensitivity was relatively low.

Background: This study assessed the diagnostic performance of the 0-hour/1-hour (0/1-h) algorithm to rule in and rule out acute myocardial infarction (MI) in patients presenting to the emergency department (ED) for suspected acute coronary syndrome without ST-segment elevation, as recommended in the 2015 European Society of Cardiology (ESC) guideline.

Methods and Results: Following the Preferred Reporting Items for a Systematic Review and Meta-analysis of Diagnostic Test Accuracy (PRISMA-DTA) guidelines, a systematic review was conducted using the PubMed database from inception to March 31, 2020. We included any article published in English investigating the diagnostic performance of the ESC 0/1-h algorithm for diagnosing MI in patients with chest pain visiting the ED. Of 651 studies identified as potentially available for the study, 7 studies including 16 databases were analyzed. A meta-analysis of the diagnostic accuracy of the 0/1-h algorithm using high-sensitivity cardiac troponin I (hs-cTn) with 6 observational databases showed a pooled sensitivity of 99.3% (95% confidence interval [CI] 98.5–99.7%) and a pooled specificity of 90.1% (95% CI 80.7–95.2%). A meta-analysis of the diagnostic accuracy of 10 observational databases of the ESC 0/1-h algorithm using hs-cTn revealed a pooled sensitivity of 99.3% (95% CI 96.9–99.9%) and a pooled specificity of 91.7% (95% CI 83.5–96.1%).

Conclusions: Our results demonstrate that the ESC 0/1-h algorithm can effectively rule in and rule out patients with non-ST-segment elevation MI.