Diagnostic Performance of High-Sensitivity Troponin T, Myeloperoxidase, and Pregnancy-Associated Plasma Protein A Assays for Triage of Patients with Acute Myocardial Infarction

BACKGROUND: Early diagnosis is the cornerstone of management of acute myocardial infarction (AMI). We aimed to compare the diagnostic accuracy of high-sensitivity troponin T (hs-cTnT) with myeloperoxidase (MPO) and pregnancy-associated plasma protein A (PAPP-A) for early diagnosis of AMI in patients at the time of presentation to the emergency department (ED). METHODS: We enrolled 289 patients who presented at the ED of the National Institute of Heart Disease (NIHD) Rawalpindi, Pakistan, within 4 hr of onset of chest pain. Clinical assessment, electrocardiography (ECG), and angiography were carried out. Blood samples were collected at 0, 3, 6, and 12 hr. Analyses of plasma hs-cTnT, MPO, and PAPP-A were carried out using commercial kits. RESULTS: Out of 289 subjects who presented to the ED, we diagnosed 180 patients with coronary heart disease as having AMI (N= 61) and 119 as without AMI (stable coronary artery disease, N=61; unstable angina, N=58). Compared to non-AMI patients, the patients with AMI had significantly higher levels (represented here as median [inter quartile range]) of plasma hs-cTnT (136 [39-370] vs. 12 [7-21] ng/L), MPO (906 [564-1,631] vs. 786 [351-1,299] pmol/L) and PAPP-A (5.78 [2.67-13.4] vs. 2.8 [1.8-4.9] mIU/L). Receiver operator characteristic curves (95% CI) for hs-cTnT (0.952 [0.909-0.978]) were significantly higher (P<0.001) than those for MPO (0.886 [0.830-0.929]) and PAPP-A (0.797 [0.730-0.854]), with AMI sensitivity and specificity percentages of 87% and 98% (hs-cTnT), 82% and 84% (MPO), and 65% and 87% (PAPP-A), respectively. CONCLUSIONS: The diagnostic performance of hs-cTnT was superior to that of MPO and PAPP-A for early triage and diagnosis of AMI among patients of coronary heart disease presenting with chest pain to the ED.