Fast-track high-sensitive cardiac troponin T algorithm for diagnosis of non-ST-elevation myocardial infarction in older patients at the emergency department

Abstract

Purpose: Age >70 years is an independent factor associated with elevated high-sensitivity troponin T (hs-cTnT) values in Emergency Department (ED) patients. We examined whether an algorithm implementing a serial hs-cTnT measurement at presentation (0h) and at 3h after presentation (3h) is helpful for early diagnosis of non-ST-elevation myocardial infarction (NSTEMI) in older patients. Methods: Consecutive unselected patients ≥70 years presenting to our ED were enrolled in a prospective diagnostic study. The final diagnosis of NSTEMI was adjudicated by two independent cardiologists and an algorithm for rule-in and rule-out of NSTEMI was developed using classification and regression tree analysis. Results: Among 306 patients (mean age 81±6 years), 38 (12%) patients had NSTEMI. Accuracy to diagnose NSTEMI was significantly higher for hs-cTnT measurements at 3h vs. 0h (area under the receiver operating characteristic curve (AUC) 0.88 vs. 0.82, p=0.0038) and for absolute vs. relative hs-cTnT delta changes (AUC 0.89 vs. 0.69, p<0.001). A diagnostic algorithm using hs-cTnT values at presentation and absolute delta changes values ruled-in NSTEMI in 23% and ruled-out NSTEMI in 35% of patients. For patients neither fulfilling the rule-in nor the rule-out criteria, an observational zone was established. Cumulative 1-year survival was 79.4%, 88.5% and 99.1% in patients classified as rule-in, observational zone and rule-out, respectively. Conclusions: In older patients serial hs-cTnT measurements and absolute delta-changes at 3h were valuable for early diagnosis of NSTEMI. An algorithm ruled-in NSTEMI in one quarter of patients with high risk and ruled-out NSTEMI in one third with low risk.