In an AACC webinar on April 26, Fred S. Apple, PhD, DABCC hopes to educate laboratorians and clinicians on high-sensitivity cardiac troponin (hs-cTn) I and T assays, what defines an hs-cTn assay, and how they should be properly applied in laboratory medicine and clinical practice.
Labs face new challenges in cTn testing, now that the U.S. Food and Drug Administration (FDA) has approved a new assay for use in the United States. CLN Stat previously reported on Roche Diagnostics’ Elecsys Troponin T (TnT) Gen 5 Stat, which delivers results in just 9 minutes, reducing the time it takes a more conventional assay to diagnose heart attack by several hours.
Although Roche is marketing this assay as “high sensitivity,” Apple, the medical director of clinical laboratories at Hennepin County Medical Center and laboratory medicine and pathology professor at the University of Minnesota in Minneapolis, plans to clarify what an hs-cTn assay is, and why Roche’s new product doesn’t necessarily meet that definition. “The evidence will speak for itself whether this assay is high sensitivity or not. FDA hasn’t classified any assay in the U.S. as high sensitivity, and it doesn’t call the Roche assay high sensitivity, either—it refers to it as the Gen 5.” Despite its fast turnaround time and high analytical precision, the Gen 5 assay appears to have different 99th-percentile upper reference limit values than an equivalent assay used in Europe and the rest of the world.
“Labs need to know how to get comfortable with implementing this assay into U.S. practice,” as its use recognizes for the first time in the United States sex-specific 99th percentiles: 14 ng/L for women and 22 ng/L for men, he said. “It will be important to understand how normal subjects were vetted and the statistic used to define the 99th percentile.”
Apple also noted that FDA appears to have limited Roche to reporting concentrations to the Gen 5 Stat cTnT assay’s limit of quantitation (LoQ, 20% coefficient of variation concentration) at 6ng/L. Yet, the Roche assay’s limit of detection (LoD) is 3 ng/L. This indicates that studies published on this assay predicated on 3 ng/L and 5 ng/L cutoffs will need to be re-evaluated at 6 ng/L, Apple said.
As part of his talk, Apple plans to show some analytical and clinical data that compares the Roche Gen 5 assay with similar hs-cTnI assays developed by other manufacturers that meet International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) criteria for a hs-cTn assay, he said.
Apple will discuss how the IFCC’s Task Force on the Clinical Application of Cardiac Bio-Markers defines hs-cTn assays, and how these assays improve precision and analytical characteristics.
He’ll also review what evidence-based strategies and appropriate test utilization practices labs should consider using for hs-cTn assays in patients presenting with a clinical indication of myocardial injury, including their role in ruling in/out myocardial injury and infarction in patients presenting with acute and chronic disease.
“I’ll discuss the power of these assays for risk stratifying and outcomes assessment of patients for adverse cardiac events and mortality predicated on baseline samples in patients with low cTn concentrations and normal EKGs,” he said.
Laboratory directors, lab supervisors, and lead technologists who perform and/or review cTn results are encouraged to attend this webinar. Register now and earn 1.0 ACCENT points.