Troponin T and quantitative ST-segment depression offer complementary prognostic information in the risk stratification of acute coronary syndrome patients

Abstract

OBJECTIVES Our primary objective was to examine the prognostic relationship between baseline quantitative ST-segment depression (ST ↓) and cardiac troponin T (cTnT) elevation. The secondary objectives were to: 1) examine whether ST ↓ provided additional insight into therapeutic efficacy of glycoprotein IIb/IIIa therapy similar to that demonstrated by cTnT and 2) explore whether the time to evaluation impacted on each marker's relative prognostic utility. BACKGROUND The relationship between the baseline electrocardiogram (ECG) and cTnT measurements in risk-stratifying patients presenting with acute coronary syndromes (ACS) has not been evaluated comprehensively. METHODS The study population consisted of 959 patients enrolled in the cTnT substudy of the Platelet IIb/IIIa Antagonism for the Reduction of Acute coronary syndrome events in a Global Organization Network (PARAGON)-B trial. Patients were classified as having no ST ↓ (n = 387), 1 mm ST ↓ (n = 433), and ST ↓ ≥2 mm (n = 139). Forty-percent (n = 381) were classified as cTnT-positive based on a definition of ≥0.1 ng/ml. RESULTS Six-month death/(re)myocardial infarction rates were 8.4% among cTnT-negative patients with no ST ↓ and 26.18% among cTnT-positive patients with ST ↓ ≥2 mm. On ECGs done after 6 h of symptom onset, ST ↓ ≥2 mm was associated with higher risk compared to its presence on ECGs done earlier (odds ratio [OR] 7.3 vs. 2.1). In contrast, the presence of elevated cTnT within 6 h of symptom was associated with a higher risk of adverse events compared with elevations after 6 h (OR 2.4 vs. 1.5). CONCLUSIONS Quantitative ST ↓ and cTnT status are complementary in assessing risk among ACS patients and both should be employed to determine prognosis and assist in medical decision making