Troponin Predicts Safe Discharge for Coronary Patients

A high-sensitivity troponin test accurately predicted 30-day rates of multiple adverse cardiac events (MACE) in a study that involved more than 1500 emergency department (ED) patients.

Emergency physicians are tasked with stratifying risk for patients presenting with potential acute coronary syndrome, said William F. Peacock, MD, of Baylor College of Medicine, Houston, Texas, in a presentation at the American College of Emergency Physicians (ACEP) 2021 Scientific Assembly.

"In the era of 'contemporary' troponin (Tn) assays, patients with a Tn above the upper reference level (99th percentile of a healthy population) were commonly admitted," Peacock said. The remaining patients were risk-stratified on the basis of scoring systems (ie, TIMI [Thrombolysis in Myocardial Infarction], HEART [History, Electrocardiography, Age, Risk Factors, Troponin], and EDACS [Emergency Department Assessment of Chest Pain]).

A strategy for identifying low-risk patients in the ED involved use of a nondiagnostic electrocardiogram, two negative troponin measures taken at least 3 hours apart and at least 3 hours after symptom onset, and risk scores on TIMI, HEART, and EDACS, Peacock noted.

It has been shown that high-sensitivity troponin (hsTn) assays can detect very low concentrations of Tn and can identify more low-risk patients, but the role of further risk stratification after use of hsTn assays has not been well studied, he said. The definition of an hsTn is an assay that has coefficient of variation at the 99th percentile of the reference population, with at least 50% measurable concentrations below the 99th percentile and above the assay limit of detection (LoD), according to the International Federation of Clinical Chemistry, Peacock said. The hsTn also measures at least 50% of healthy individuals above the LoD, and measures men and women separately, he added.

Peacock and colleagues conducted a prospective study of 1520 patients. Of those, 1493 did not have MACE. Twenty-seven patients with MACE were included in order to evaluate the impact of the risk scores after hsTn testing.

The researchers gathered data on risk stratification and obtained blood samples at 1, 2, 3–4, and 6–12 hours from baseline. They evaluated patients with the cardiac-specific Access High Sensitivity Troponin I (hsTNI) assay (Beckman Coulter, Inc), and examined MACE rates 30 days after the ED visit. The median age of the study population was 57 years, 59.3% were men, and 65.7% were White.

Overall, the 30-day MACE rate was 0.5% for patients with hsTn scores below the assay's LoD. It was approximately 10 times higher (5%) when the hsTnI score was greater than the upper reference level. Differences were minimal for 30-day MACE rates among discharge-scored cohorts and observation-scored cohorts for the three scores and the hsTnI.

Risk scoring for patients with hsTn in the gray zone, defined as scores greater than the assay LoD and less than the upper reference level, led to observation rates of 29.5%, 18.5%, and 25.7% for TIMI, HEART, and EDACS, respectively, compared to 19.8% for hsTnI. Discharge rates using TIMI, HEART, and EDACS were 15%, 24.5%, and 18.8%, respectively, compared to 24.7% for hsTnI.

The study findings were limited by several factors, including the retrospective design and the relatively low MACE rate, Peacock said. No patients were discharged on the basis of study findings, and different outcomes may occur in populations with higher MACE rates, he said.

However, the results support the value of hsTnI as "an excellent predictor of safe discharge and 30-day MACE in patients presenting to the ED with suspected acute coronary syndromes," he said. Clinicians should reconsider the need for risk scores, which may prompt unnecessary admissions, when hsTnI is an option, he concluded.

Grant support for the study was provided by Beckman-Coulter, Siemens, Abbott, Roche, and Ouidel.

American College of Emergency Physicians (ACEP) 2021 Scientific Assembly: Abstract 98.

Ann Emerg Med. Published online October 1, 2021. Full text

Heidi Splete is a freelance medical journalist with 20 years of experience.

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