Diagnostic Utility of Cardiac Biomarkers in Discriminating Takotsubo Cardiomyopathy From Acute Myocardial Infarction

BackgroundTakotsubo cardiomyopathy (TC) mimics acute myocardial infarction (AMI). We postulated that ventricular dysfunction in TC in the absence of significant myocardial necrosis would produce higher B-type natriuretic peptide (BNP)/troponin T (TnT) and BNP/creatine kinase MB fraction (CKMB) ratios than in AMI.Methods and ResultsWe studied 58 consecutive TC (age 65.8 ± 82.9) and 97 AMI patients (age 59.8 ± 83.4). The ratios of BNP/TnT and BNP/CKMB were calculated with the use of first simultaneously drawn laboratory values. Receiver operating characteristic curves were used to distinguish TC from AMI with 95% specificity based on cardiac biomarker ratios. Median BNP/TnT and BNP/CKMB ratios were, respectively, 1,292 [interquartile range 443.4–2,657.9] and 28.44 [13.7–94.8] in the TC group and 226.9 [69.91–426.32] and 3.63 [1.07–10.02] in the AMI group (P < .001). TC can be distinguished from AMI with 95% specificity with the use of BNP/TnT ratio ≥1,272 (sensitivity 52%) and BNP/CKMB ratio ≥29.9 (sensitivity 50%).ConclusionsThe value of BNP is significantly higher in TC than in AMI. Early BNP/TnT and BNP/CKMB ratios help to differentiate TC from AMI with greater accuracy than BNP alone.