Department of Family Medicine, University of North Carolina at Chapel Hill (Drs. Lam and Mounsey); Naval Hospital Camp Lejeune, NC, and Uniformed Services University of the Health Sciences, Bethesda, MD (Dr. Hwang) Anne_Mounsey@med.unc.edu
The authors reported no potential conflict of interest relevant to this article.
The contents of this article are solely the views of the authors and do not necessarily represent the official views of the Uniformed Services University of the Health Sciences, the US Navy, the US military at large, the US Department of Defense, or the US government.
Right ventricular strain. Other findings that reflect right ventricular strain, but are much less common, are complete or incomplete right bundle branch block, prominent S wave in lead I, Q wave in lead III, and T-wave inversion in lead III (S1Q3T3; the McGinn-White sign) and in leads V1-V4.8
The utility of troponin and high-sensitivity troponin testing
Clinical evaluation and EKG findings are unable to diagnose or exclude ACS without the use of the cardiac biomarker troponin. In the past decade, high-sensitivity troponin assays have been used to stratify patients at risk of ACS.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.13-16
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.17 Studies in which the HEART score (History, Electrocardiography, Age, Risk factors, Troponin) was combined with high-sensitivity troponin measurement show that this pairing is promising in reducing unnecessary admissions for chest pain.18 (For a description of this tool, see the discussion of the HEART score that follows.) Carlton and colleagues18 showed that a HEART score ≤ 3 and a negative high-sensitivity troponin I level had a negative predictive value of ≥ 99.5% for AMI.
Clinical decision tools: Who needs care? Who can go home?
Given the varied presentations of patients with life-threatening causes of chest pain, it is challenging to confidently determine who is safe to send home after initial assessment. Guidance in 2014 from the American Heart Association and American College of Cardiology recommends risk-stratifying patients for ACS using clinical decision tools to help guide management.19,20 The American College of Physicians, in its 2015 guidelines, also recommends using a clinical decision tool to assess patients when there is suspicion of PE.21 Clinical application of these tools identifies patients at low risk of life-threatening conditions and can help avoid unnecessary intervention and a higher level of care.
Tools for investigating ACS
The Marburg Heart Score22 assesses the likelihood of CAD in ambulatory settings while the HEART score assesses the risk of major adverse cardiac events in ED patients.23 The Diamond Forrester criteria can be used to assess the pretest probability of CAD in both settings.24
