High-sensitivity troponins mean a lower limit of detection. Picking up these lower quantitative values for circulating troponin – and new reference limits for the 99th percentile of normal – has required an adjustment in perspective with respect towards making the diagnosis of acute coronary syndrome. Now, the question with these more sensitive assays becomes: should we adjust our clinical considerations to incorporate sex-specific reference intervals?
This brief analysis from the UTROPIA study looks specifically at the downstream MACE in patients whose serial troponin measurements fall between the limit of detection and the sex-specific 99th percentile intervals. For this Abbott assay, that means 34 ng/L for men and 16 ng/L for women. In their 180-day follow-up period, they found the incidence of major adverse cardiac events was vanishingly small for those with undetectable levels of circulating troponin. However, those with any circulating troponin – even below the 99th percentile reference interval – were vastly more likely to experience an event within the next 180 days, reaching about 10% incidence of MACE. Importantly, however, the distributions of probability for downstream MACE were similar with regard to the measured value with respect to the sex-specific 99th percentile.
This confirms some of what we already knew: any troponin is bad troponin, even if it’s lower than the 99th percentile. Then, this also validates sex-specific 99th percentiles, as percentile levels conveyed similar risk between men and women.
Just another insight into the next level of sophistication for use of these assays in assessing patients with potential ACS, and for downstream anatomic assessment and preventive interventions.
“Clinical Features and Outcomes of Emergency Department Patients With High- Sensitivity Cardiac Troponin I Concentrations Within Sex-Specific Reference Intervals”
https://www.ahajournals.org/doi/10.1161/CIRCULATIONAHA.118.038284