Comparison of quantitative flow ratio value of left anterior descending and circumflex coronary artery in patients with Takotsubo syndrome.

Takotsubo syndrome (TTS) is an acute cardiac event without epicardial coronary obstruction but often with reversible ventricular motion abnormalities. Quantitative flow ratio (QFR) is a novel approach to evaluate the coronary stenosis significance on the basis of 3-dimensional quantitative coronary angiography (3D-QCA) and contrast flow by Thrombolysis in Myocardial Infarction frame count. This study aimed to evaluate and compare the QFR value in the left anterior descending artery (LAD) and the left circumflex artery (LCx) in patients with TTS. This retrospective and observational study enrolled 30 patients with TTS who underwent coronary angiography. We evaluated the QFR data using the 3D-QCA analysis and compared the QFR data in the LAD and the LCx. No significant differences were observed in terms of flow velocity, percent diameter stenosis, minimum lumen diameter, and reference diameter between LAD and LCx. However, vessel QFR in the LAD was significantly reduced compared with that in the LCx (0.98 [0.94 to 0.99] vs. 1.00 [0.99 to 1.00], P < 0.001). Ejection fraction at baseline and initial troponin-I levels were not correlated with the vessel QFR both in the LAD and the LCx. The QFR value in the LAD was significantly reduced compared to that in the LCx in patients with TTS.