Troponin test shows potential in detecting CAD—but imaging still needed to confirm
A high-sensitivity troponin I (hsTnI) assay was independently predictive of coronary artery disease (CAD) in patients with stable chest pain in the outpatient setting, researchers reported in JACC: Cardiovascular Imaging. However, it’s not ready to be used as a standalone diagnostic tool for CAD.
Troponin levels above the 99th-percentile cutoff of six nanograms per liter in apparently healthy individuals have been used to diagnose cases of acute myocardial infarction (MI). But the development of assays with the ability to detect much lower levels of hsTnI has given researchers hope these tests could also identify CAD.
“Chest discomfort is one of the most commonly-encountered complaints in outpatient medicine, and represents a major diagnostic challenge as patients often present with a broad range of non-specific symptoms or signs,” said lead author James Januzzi Jr., MD, with Massachusetts General Hospital. “Classical history and physical examination for determining cause of chest discomfort is neither sensitive nor specific to identify obstructive CAD as the cause of this common complaint. Having a diagnostic blood test to enhance ability to rapidly and accurately support clinical judgment, identify or rule-out CAD would address these challenges.”
Januzzi and colleagues studied 1,844 stable patients with chest pain who also received coronary CT angiography (CTA). After adjusting for demographics and clinical characteristics, each incremental increase in hsTnI levels was associated with 15 percent greater odds a patient would have at least 50 percent stenosis in a vessel and 25 percent greater odds they would have at least 70 percent stenosis.
But the researchers noted the assay’s prediction of the presence of CAD wasn’t as specific as its ability to distinguish cases of MI. Notably, 98.5 percent of study participants had measurable hsTnI ranging from 0.5 ng/L to 1,434.6 ng/L. The median concentration was 1.5 ng/L.
“Although our data suggest more refined and sensitive Tn methods may be influenced by presence of obstructive CAD in a more stable chest pain population, stand-alone measurement of hsTnI cannot replace imaging for the diagnosis or exclusion of coronary atherosclerosis in stable patients,” Januzzi and coauthors wrote. “However, an integrative role of hsTnI with clinical variables and imaging (including coronary CTA, coronary artery calcium scoring, or myocardial perfusion imaging) to optimize diagnostic accuracy for those patients at higher risk is currently being explored.”
The researchers noted their findings may not extend to other hsTn tests, which could have varying degrees of sensitivity. Singulex, the company whose assay was used in the trial, partially sponsored the study and has provided grant support to Januzzi.
Mary joined TriMed Media in 2003. She was the founding editor and editorial director of Health Imaging, Cardiovascular Business, Molecular Imaging Insight and CMIO, now known as Clinical Innovation + Technology. Prior to TriMed, Mary was the editorial director of HealthTech Publishing Company, where she had worked since 1991. While there, she oversaw four magazines and related online media, and piloted the launch of two magazines and websites. Mary holds a master’s in journalism from Syracuse University. She lives in East Greenwich, R.I., and when not working, she is usually running around after her family, taking photos or cooking.