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UTROPIA: Single high-sensitivity cardiac troponin I measurement at presentation may rule out acute MI
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High-sensitivity cardiac troponin I, either alone or in conjunction with a normal ECG, ruled out acute type 1 and type 2 MI and identified patients at low risk for acute MI or adverse events at 30 days, according to a study in The American Journal of Medicine.
“A number of studies have been coming out addressing the value of a single high-sensitivity cardiac troponin measurement to identify patients at low risk,” Yader Sandoval, MD, lead author of the study and an interventional cardiology fellow at Hennepin County Medical Center in Minneapolis and Minneapolis Heart Institute at Abbott Northwestern Hospital, told Cardiology Today. “Our study examines the high-sensitivity cardiac troponin I assay in a United States population, and explores different thresholds, as well as addresses the rule-out of both type 1 and 2 [MI].”
Identifying acute MI
In the UTROPIA study, researchers analyzed a prospective cohort of 1,631 adults presenting to the ED in whom cardiac troponin I measurements were obtained on clinical indication.
“We examined two single high-sensitivity cardiac troponin I measurement strategies to rule-out acute [MI],” Sandoval told Cardiology Today. “One strategy focused on the 1.9 ng/L limit of detection, an analytical threshold below the 99th percentile upper reference limit, and the other strategy used a 5 ng/L concentration threshold that was derived and validated in the HIGH-STEACS study.” The two measurement strategies were examined alone and in combination with a normal ECG to evaluate multiple outcomes.
Researchers defined the diagnostic outcome as acute MI, including type 1 and type 2 MI during the index hospitalization. The safety outcome was a composite of acute MI or cardiac death at 30 days, including events occurring during the index hospitalization.
Of the patients analyzed, 27% (n = 444) presented with hs-cTnI less than the limit of detection and 50% (n = 812) had hs-cTnI < 5 ng/L using the High-STEACS threshold. Acute MI occurred in 10.4% (n = 170) of patients, including 4.2% (n = 68) with type 1 MI and 6.3% (n = 102) with type 2 MI.
Sensitivity and negative predictive value
The negative predictive value for acute MI or cardiac death in those with hs-cTnI less than the limit of detection was 99.6% (95% CI, 98.9-100), and sensitivity was 98.8% (95% CI, 97.2-100). With a normal ECG, negative predictive value was 99.6% (95% CI, 98.8-100) and sensitivity was 99.4% (95% CI, 98.3-100).
For hs-cTnI < 5 ng/L, the negative predictive value and sensitivity for acute MI and cardiac death was 98.9% (95% CI, 98.2-99.6) and 94.7% (95% CI, 91.4-98.1), respectively. In combination with a normal ECG, the High-STEACS approach offered a negative predictive value of 99.5% (95% CI, 98.8-100) and a sensitivity of 98.8% (95% CI, 97.2-100).
“[This has implications for clinical practice], even among chest pain patients,” Stephen W. Smith, MD, an emergency medicine physician at Hennepin County Medical Center, told Cardiology Today. “Unless you have some reason for high clinical suspicion of [ACS], then patients with a single initial high-sensitivity cardiac troponin I below the limit of detection or below the limit of detection with a normal [ECG] are eligible for discharge if they have no other reason to be admitted.”
“By expediting the identification of patients at low risk, these strategies may expedite triaging, reducing overcrowding in [EDs] and observations units across the United States, facilitate early discharge in selected patients and reduce costs,” Sandoval told Cardiology Today.
“[Regarding further research], there needs to be a direct comparison between [high-sensitivity]-hs-cTnI and [high-sensitivity]-cTnT, assays, especially addressing early presenters,” Fred S. Apple, PhD, DABCC, medical director of clinical laboratories, clinical chemistry, clinical and forensic toxicology and point-of-care testing at Hennepin County Medical Center, told Cardiology Today. – by Darlene Dobkowski
Disclosure: The study was partially funded through a grant from Abbott Diagnostics and the Minneapolis Medical Research Foundation. Apple reports consulting for Metanomics Health and Philips Healthcare Incubator; serving on the board of directors for HyTest Ltd.; receiving an honorarium from Abbott POC and Instrumentation Laboratory; serving as an unsalaried investigator for Abbott Diagnostics, Alere, Becton Dickinson, Nanomix, Ortho-Clinical Diagnostics, Roche Diagnostics, Siemens Healthcare and Singulex; and is the associate editor for Clinical Chemistry. Sandoval reports advising for Roche Diagnostics without a salary. Smith reports consulting for Alere, advising for Roche Clinical Diagnostics, and performing paid work for Siemens.
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