NT-proBNP/cardiac troponin T ratio >7.5 on the second day of admission can differentiate Takotsubo from acute coronary syndrome with good accuracy

Abstract

Background: Takotsubo syndrome (TTS) is not usually diagnosed until patients with suspected acute coronary syndrome (ACS) and echocardiographically detected apical aneurysm are found to have "normal" coronary angiography (CA). Our aim was to explore whether cardiac biomarkers can contribute to the early diagnosis of TTS.

Methods: Ratios of N-terminal-pro brain natriuretic peptide (NT-proBNP) and high-sensitivity cardiac troponin T (cTnT) both expressed in pg/mL [admission and the 3 following days] were compared in 38 patients with TTS and 114 ACS patients of whom 58 had non-ST-elevation myocardial infarction (NSTEMI).

Results: NT-proBNP/cTnT ratio at admission and during the following 3 days was significantly higher in TTS compared to patients with ACS [18.4 (8.7-41.7) vs 2.9 (0.8-6.8), 29.6 (14.3-53.7) vs 1.2 (0.5-2.7), 30.0 (11.6-50.9) vs 1.7 (0.5-3.0), 27.8 (11.3-42.6) vs 1.4 (0.6-2.8), respectively, all <0.001]. Βest discrimination of TTS from ACS was possible with the ratio of NT-proBNP/cTnT on the 2^nd day. A cut-off value of NT-proBNP/cTnT ratio >7.5 had a sensitivity of 97.3%, a specificity of 95.4% and an accuracy of ∼96% in detecting TTS as opposed to ACS. Furthermore, the ratio of NT-proBNP/cTnT preserved its discriminatory value in the subgroup of patients with NSTEMI. In particular, an NT-proBNP/cTnT ratio >7.5 on the 2^nd day had a sensitivity of 97.3%, a specificity of 91.4%, and an accuracy of 93.7% in differentiating TTS from NSTEMI.

Conclusions: An NT-proBNP/cTnT ratio >7.5 on the 2^nd day of admission can be useful for the early identification of TTS among selected patients initially presenting with ACS, a ratio more clinically useful in the setting of NSTEMI.

Keywords: Takotsubo syndrome; acute coronary syndrome; brain natriuretic peptide; cardiac troponin.