A comprehensive validation of very early rule-out strategies for non-ST-segment elevation myocardial infarction in emergency departments: protocol for a multicentre prospective cohort study.

INTRODUCTION: Recent advances in troponin sensitivity enabled early and accurate judgement of ruling-out myocardial infarction, especially non-ST elevation myocardial infarction (NSTEMI) in emergency departments (EDs) with development of various prediction-rules and high-sensitive-troponin-based strategies (hs-troponin). Reliance on clinical impression, however, is still common, and it remains unknown which of these strategies is superior. Therefore, our objective in this prospective cohort study is to comprehensively validate the diagnostic accuracy of clinical impression-based strategies, prediction-rules and hs-troponin-based strategies for ruling-out NSTEMIs. METHODS AND ANALYSIS: In total, 1500 consecutive adult patients with symptoms suggestive of acute coronary syndrome will be prospectively recruited from five EDs in two tertiary-level, two secondary-level community hospitals and one university hospital in Japan. The study has begun in July 2018, and recruitment period will be about 1 year. A board-certified emergency physician will complete standardised case report forms, and independently perform a clinical impression-based risk estimation of NSTEMI. Index strategies to be compared will include the clinical impression-based strategy; prediction rules and hs-troponin-based strategies for the following types of troponin (Roche Elecsys hs-troponin T; Abbott ARCHITECT hs-troponin I; Siemens ADVIA Centaur hs-troponin I; Siemens ADVIA Centaur sensitive-troponin I). The reference standard will be the composite of type 1 MI and cardiac death within 30 days after admission to the ED. Outcome measures will be negative predictive value, sensitivity and effectiveness, defined as the proportion of patients categorised as low risk for NSTEMI. We will also evaluate inter-rater reliability of the clinical impression-based risk estimation. ETHICS AND DISSEMINATION: The study is approved by the Ethics Committees of the Kyoto University Graduate School and Faculty of Medicine and of the five hospitals where we will recruit patients. We will disseminate the study results through conference presentations and peer-reviewed journals.

Advantage of CPR-first over call-first actions for out-of-hospital cardiac arrests in nonelderly patients and of noncardiac aetiology.

AIM: To assess the benefit of immediate call or cardiopulmonary resuscitation (CPR) for survival from out-of-hospital cardiac arrests (OHCAs). METHODS: Of 952,288 OHCAs in 2005-2012, 41,734 were bystander-witnessed cases without prehospital involvement of physicians but with bystander CPR (BCPR) on bystander's own initiative. From those OHCAs, we finally extracted the following three call/BCPR groups: immediate Call+CPR (N=10,195, emergency call/BCPR initiated at 0 or 1 min after witness, absolute call-BCPR time interval=0 or 1 min), immediate Call-First (N=1820, emergency call placed at 0 or 1 min after witness, call-to-BCPR interval=2-4 min), immediate CPR-First (N=5446, BCPR initiated at 0 or 1 min after witness, BCPR-to-call interval=2-4 min). One-month neurologically favourable survivals were compared among the groups. Critical comparisons between Call-First and CPR-First groups were made considering arrest aetiology, age, and bystander-patient relationship after confirming the interactions among variables. RESULTS: The overall survival rates in immediate Call+CPR, Call-First, and CPR-First groups were 11.5, 12.4, and 11.5%, respectively without significant differences (p=0.543). Subgroup analyses by multivariate logistic regression following univariate analysis disclosed that CPR-first group is more likely to survive in subgroups of noncardiac aetiology (adjusted odds ratio; 95% confidence interval, 2.01; 1.39-2.98) and of nonelderly OHCAs (1.38; 1.09-1.76). CONCLUSIONS: Immediate CPR-first action followed by an emergency call without a large delay may be recommended when a bystander with sufficient skills to perform CPR witnesses OHCAs in nonelderly people and of noncardiac aetiology.