Cardiac troponin testing in acute coronary syndrome: personalized thresholds or generalized cut-offs?
Despite the diagnosis of acute coronary syndrome (ACS) has engaged the minds of many clinicians and laboratory professionals for decades, the introduction of high-sensitivity immunoassay for measuring cardiac troponins has dramatically contributed to enhance the diagnostic efficiency and has almost revolutionized the clinical decision making. Serial measurements at fixed time points of these biomarkers remain the gold standard for increasing the diagnostic specificity of cardiac troponin testing. However, irrespective of the ongoing debate around the optimal timing of repeated testing, what has not been definitely clarified is whether personalized thresholds may be better than using generalized cut-offs. Due to the many physiological conditions and non-ischemic disorders which potentially impact the measurable troponin concentration, a personalized approach entailing multiple decision limits does not appear suitable, even when limited to longitudinal monitoring of individual patient data. The use of a single cut-off, much lower than the upper reference limit (URL) and likely corresponding to the limit of detection of the assay, seems now the most promising and efficient strategy combined with 2–3 hours repeated testing. This approach may allow to rapidly and safely ruling out non-ischemic causes of chest pain, but may also considerably increase the specificity of cardiac troponin testing in unselected populations.