Objective High-sensitivity cardiac troponin T (hs-cTnT) is widely used for the diagnosis of acute myocardial infarction (AMI). The current cut-off value of 0.014 ng/mL was determined based on the 99th percentile of a normal reference population; however, little data exist regarding the appropriate cut-off value in the elderly (≥75 years). Accordingly, we aimed to investigate the accuracy of the current cut-off value in an elderly population.

Methods We assessed 355 consecutive patients (mean age =66.7±16.1 years, male =210) whose hs-cTnT levels were measured at Kanazawa University Hospital from January 2014 to July 2015. Twenty-six patients were eventually diagnosed with AMI. Hs-cTnT was measured during a visit to the emergency or outpatient department. Receiver operating characteristic (ROC) curves were assessed to determine the appropriate cut-off levels, yielding the maximum sensitivity and specificity while dividing the subjects into two groups according to ages (≥75 or ≤74 years).

Results The appropriate overall cut-off value was 0.038, the sensitivity and specificity of which were 85% and 89%, respectively, with an area under the ROC curve (AUC) of 0.945 overall. The conventional cut-off value (99th percentile: 0.014 ng/mL) provided low specificity, particularly in the elderly or those with renal dysfunction. In contrast, a calculated appropriate cut-off provided higher sensitivity with significantly larger c-statistics in the elderly (0.940 vs. 0.629, p<0.001).

Conclusion When measuring hs-cTnT, careful assessments are needed in elderly subjects.