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

Abstract

IntroductionRecent 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 analysisIn 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 disseminationThe 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.

Comprehensive validation of early diagnostic algorithms for myocardial infarction in the emergency department

“… 4–6 The details and thresholds for each algorithm are described in the Supplementary Material and protocol ( Supplementary Tables S2–S5 and Figures S1–S3 ). 9 …”

“…Assuming that 5–10% of patients had the primary clinical outcome, with a sensitivity and specificity of 95% and 55%, respectively, 1500 patients were necessary to achieve the lower limit of 95% CI for the NPV was to surpass 98%. 9 , 15–17 However, we stopped enrollment on July 2021 due to slow recruitment. We initially planned for consecutive cases, but in practice, it turned out to be a convenient sampling.…”

Tips and tools to help refine your approach to chest pain

“…11,12 Many protocols now exist using short interval (2-3 hours), high-sensitivity troponin testing to identify patients at low risk of myocardial infarction who can be safely discharged from the ED after 2 normal tests of the troponin level. [13][14][15][16] An elevated troponin value alone, however, is not a specific indicator of ACS; troponin can be elevated in the settings of myocardial ischemia related to increased oxygen demand (Type 2 non-STEMI) and decreased renal clearance. Consideration of the rate of rising and falling levels of troponin, its absolute value > 99th percentile, and other findings is critical to interpreting an elevated troponin level.…”