High-Sensitivity Cardiac Troponin on Presentation to Rule Out MI

Quick Takes

  • A randomized controlled trial involving approximately 31,500 patients enrolled across seven centers in Scotland investigated an early rule-out strategy using high-sensitivity troponin I measured with the Abbott ARCHITECTSTAT assay.
  • The intervention was the early rule-out pathway, in which MI is ruled out in patients with troponin concentrations <5 ng/L at presentation, or if delta <3 ng/L and remain below the 99th centile after 3 hours.
  • Implementation of an early rule-out pathway for patients with suspected acute coronary syndrome was safe and reduced length of stay by 3.3 hours and hospital admissions by 59%.

Study Questions:

Does an early rule-out pathway for myocardial infarction (MI) in the emergency department (ED) using high-sensitivity troponin I decrease length of stay?

Methods:

HiSTORIC (High-Sensitivity cardiac Troponin On presentation to Rule out myocardial InfarCtion) is a stepped-wedge cluster randomized controlled trial, which enrolled consecutive patients with suspected acute coronary syndrome across seven acute hospitals in Scotland. The hospital was the unit of randomization. The intervention was the early rule-out pathway, in which MI is ruled out in patients with troponin concentrations <5 ng/L at presentation, or if delta <3 ng/L and remain below the 99th centile after 3 hours. High-sensitivity troponin I was measured using the Abbott ARCHITECTSTAT assay. The primary efficacy outcome was length of stay. The primary safety outcome was MI or cardiac death at 30 days (primary) and 1 year (secondary).

Results:

Between 2014 and 2016, 31,492 consecutive patients with suspected acute coronary syndrome (59 ± 17 years, 45% women) were enrolled across seven hospitals. There were 14,700 (47%) and 16,792 (53%) patients assessed before and after implementation of the early rule-out pathway, respectively. Length of stay was reduced from 10.1 ± 4.1 to 6.8 ± 3.9 hours (p < 0.001) following implementation of the early rule-out pathway. The proportion of patients discharged without hospital admission increased from 50% to 71% (adjusted odds ratio [aOR], 1.59; 95% confidence interval [CI], 1.45-1.75). Before and after implementation of the early rule-out pathway, the primary safety outcome of MI or cardiac death following discharge at 30 days occurred in 57/14,700 (0.4%) and 56/16,792 (0.3%) patients, respectively. Mortality at 1 year was 2.9% in patients who underwent standard care evaluation, and 1.7% in the early rule-out pathway (aOR, 0.58; 95% CI, 0.47-0.71; p < 0.001).

Conclusions:

The early rule-out pathway for MI reduced length of stay and hospital admission without increasing cardiac events at 1 year.

Perspective:

This large multicenter trial of close to 31,500 patients from seven centers in Scotland confirms dramatic benefits of adopting an early rule-out strategy, with a 3.3-hour reduction in length of stay in the ED and a 59% decrease in hospital admission, without impacting safety. The size of the trial is considerable, and 1-year follow-up was available for 99.8% of patients, allowing adjudication of safety events. Findings are in line with observational data surrounding the High-STEACS pathway used in this trial. The potential impact of its implementation on healthcare costs is tremendous. The authors state: “A reduction in the length of stay of 3 hours could save more than $3.6 billion per annum on bed occupancy alone” in the United States. This is in comparison to standard care testing in Scotland, which involves high-sensitivity troponin measurement at presentation and 6-12 hours later. Pathways involving shorter testing times such as the RAPID-TnT 0/1 hour trial in a much smaller patient population further decreased length of hospitalization compared to a 0/3 hour pathway, but was associated with an increase in safety events.

Keywords: Acute Coronary Syndrome, Biomarkers, Cardiology Interventions, Emergency Service, Hospital, Health Care Costs, Hospitalization, Length of Stay, Myocardial Infarction, Patient Discharge, Troponin I


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