Abstract 17622: Combination of Early Brain Natriuretic Peptide/Creatine Kinase-MB Ratio and QTc Prolongation Significantly Improves Differentiation of Takotsubo Cardiomyopathy from Acute Myocardial Infarction
Background: Takotsubo Cardiomyopathy (TC) is a transient myocardial dysfunction that mimics acute myocardial infarction (AMI). Currently, these are differentiated by ruling out obstructive coronary artery disease on coronary angiography. We postulated that ventricular dysfunction in TC in absence of significant myocardial necrosis would produce different brain natriuretic peptide (BNP)/troponin T (TnT) & BNP/creatine kinase-MB (CKMB) ratio than in AMI allowing early distinction between TC & AMI.
Methods: We studied 58 consecutive TC patients (mean age 65.8±12.9 years, 98% female) divided into STEMI-like TC (n = 22) & NSTEMI-like TC (n = 36) based on initial electrocardiogram (ECG). Similarly, 97 patients (mean age 59.8±13.4 years, 79% female) with suspected AMI were divided into ST-elevation MI (n = 38) & non-ST elevation MI (n = 59). The ratios of BNP/TnT & BNP/CKMB were calculated using the first simultaneously drawn values of BNP, TnT & CKMB. ECG was analyzed for QTc prolongation. Receiver operator characteristic (ROC) curves were used to distinguish TC from AMI with 95% specificity. To aid in this distinction, a “discriminant” was developed incorporating BNP/CKMB ratio & QTc prolongation on ECG.
Results: Mean BNP/TNT & BNP/CKMB ratios were 4472±11950 & 379±549 in TC & 63.8±87.6 & 7.9±10.7 in AMI groups, respectively (p <0.001). Various ratio cut-offs to separate TC from AMI are shown in Figure. TC can be distinguished from AMI using a BNP/TnT ratio ≥ 1272 (specificity 95%, sensitivity 52%) & a BNP/CKMB ratio ≥ 29.9 (specificity 95%, sensitivity 50%). A discriminant (d) ≥ 0.448 can distinguish TC from AMI (specificity 95%, sensitivity 75%). A value of d ≥ 0.408 efficiently distinguished STEMI-like TC from actual STEMI (specificity 95%, sensitivity 81%).
Conclusion: Early BNP/TnT & BNP/CKMB ratios help differentiate TC from AMI. QTc prolongation combined with BNP/CKMB ratio gives a discriminant which distinguishes TC from MI with a significantly higher sensitivity.
- © 2012 by American Heart Association, Inc.