Troponin Limit of Detection Plus Cardiac Risk Stratification Scores to Rule Out Acute Myocardial Infarction and 30-Day Major Adverse Cardiac Events in ED Patients

Abstract

When screening for acute myocardial infarction (AMI), troponin levels below the 99th percentile, including those below the limit of detection (LOD), are considered normal. We hypothesized that a low-risk HEART Score (0–3) or ACS Pretest Probability Assessment <2% plus a single troponin below the LOD would rule out both AMI and 30-day major adverse cardiac events (MACE). We studied all patients who presented to a single academic ED and received a troponin I (Siemens Ultra Troponin I) from 9/1/13 to 11/13/13 (n=888). Demographic and clinical data were abstracted from the electronic medical record. Primary outcome was a final encounter diagnosis of MI. Secondary outcome was 30-day MACE, defined as composite of MI, revascularization, or death from a cardiac or uncertain etiology. Sensitivities of low-risk HEART score and ACS Pretest Probability <2% alone were 98% (95%CI 89–100%) and 96% (95%CI 86–100%) for AMI and 94% (95%CI 86–98%) and 95% (95%CI 88–99%), respectively, for 30-day MACE. When combined with troponin below the LOD, sensitivity for AMI was 100% (95%CI 93–100%; difference 2%, 95%CI −2% to 6%) for low-risk HEART Score and 100% (95%CI 93–100%; difference 4%, 95% CI −1.5 to 10%) for ACS Pretest Probability <2%. When combined with troponin below the LOD, sensitivity for 30-day MACE was 100% (95%CI 95–100%; difference 6%; 95%CI 1–12%) for low-risk HEART Score and 100% (95%CI 95–100%; difference 5%; 95%CI 0.2–10%) for ACS Pretest Probability <2%. Addition of a single troponin below the LOD to these scores improves sensitivity for 30-day MACE.

Prognostic Accuracy of the HEART Score for Prediction of Major Adverse Cardiac Events in Patients Presenting With Chest Pain: A Systematic Review and Meta‐analysis

“…Our search identified 778 citations (Figure ) and following removal of duplicates, we screened 557 studies, from which 62 studies underwent full‐text review. We included 29 distinct cohorts from 30 studies in the meta‐analysis . All included studies evaluated the prognostic accuracy of the HEART score using a low‐risk threshold (score between 0 and 3).…”

“…Sixteen studies evaluated the HEART score for 30‐day incidence of MACE, while 13 evaluated the HEART score for 6‐week incidence of MACE . Most studies included only patients presenting with chest pain, while five studies included patients presenting with “suspected ACS.” In 14 studies, the ECG was interpreted by an ED physician, while in seven studies the ECG was specifically interpreted by a cardiologist . Four studies computed the HEART score using high‐sensitivity troponin assays, while the remaining studies used conventional troponin T or I assays (as used in the original study) …”

Guidelines for reasonable and appropriate care in the emergency department (GRACE): Recurrent, low‐risk chest pain in the emergency department

“…Additional searches for indirect evidence yielded no relevant studies that evaluated a single troponin in ED patients with recurrent chest pain with 30‐day MACE outcome. Additional search for indirect evidence yielded nine studies 31–39 that evaluated a single troponin in ED patients with low‐risk chest pain with 30‐day MACE outcome. (Appendix ) Nearly all of these studies evaluated the use of a single high‐sensitivity troponin measurement, with only one small, single‐center study evaluating a single conventional troponin measurement 33 …”

“…After synthesizing the evidence for each question in Box 1, the small, single-center study evaluating a single conventional troponin measurement. 33 Thus, insufficient evidence exists to recommend for or against a single conventional troponin measurement in patients with recurrent, low-risk chest pain. High-sensitivity troponin assays measure cTn levels within the normal range in at least 50% of healthy individuals with high precision, defined as a coefficient of variance (CV) ≤ 10% at the 99th percentile.…”

Combined Use of High-Sensitive Cardiac Troponin, Copeptin, and the Modified HEART Score for Rapid Evaluation of Chest Pain Patients

“…To further shorten time to decision and maintain high safety presented by serial measurements, combined use of additional variables is being reassessed. According to recent studies, the use of baseline hs-Tn concentration below the limit of detection (LOD) and the mHS improved accuracy for short-term prognosis when compared to the score or troponin alone [ 24 ]. Even though lower than hs-TnT/mHS/copeptin, the hs-TnT/mHS algorithm still remains of better sensitivity/NPV than hs-TnT alone, thus reinforcing the interest for the mHS.…”