Clinical Significance of High Troponin T with Normal Creatine Kinase Levels on Ventricular Function in Acute Coronary Syndromes

Abstract

Background The role of elevated troponins to predict changes on ventricular function in patients with high creatine kinase (CK) levels has been well established; yet, little is known about the clinical significance of high troponin levels with normal CK levels. Objectives To analyze the relation between Troponin T (TnT) levels and global and regional left ventricular function in patients with acute coronary syndromes (ACS) with normal CK and CK-MB levels. Material and Methods We included patients admitted to the coronary care unit due to ACS within 48 hours from symptoms onset with elevated TnT levels measured by quantitative determination and normal CK and CK-MB levels. Biomarkers were measured at baseline, 24 and 48 hours. Left ventricular function was analyzed by two-dimensional echocardiography at admission and before discharge, and compared with the highest levels of the biomarkers. Ejection fraction, regional wall motion and global systolic longitudinal strain based on speckle-tracking technique were evaluated. Results Thirty patients with ACS were included. The highest median value of TnT was 0.13 m Conclusions High TnT values in ACS with normal CK levels do not modify global or regional left ventricular function assessed by conventional echocardiography. The evaluation of systolic strain using a more sensitive technique detects transient abnormalities. These findings might question the definition of acute myocardial infarction based on high troponin levels, considering that the classical definition is based on elevated CK values which are associated with changes in ventricular function. g/L (interquartile range, 0.07-0.25) measured 24 hours after admission. Left ventricular ejection fraction was 62.9%±10% at admission and 62.8%±10.3% before discharge. Wall motion index was 1.04±0.1 and 1.03±0.1, respectively. Systolic strain at admission was 14.93±3 and improved before discharge 16.51±3.33 (p = 0.0003).