P811Functional assessment of microcirculation in Takotsubo cardiomyopathy - a pilot study

Abstract

Background Takotsubo cardiomyopathy (TTC) is a severe cardiologic disorder with an increasing incidence that often mimics acute coronary syndrome. Both of the entities are characterized by systolic dysfunction of the left ventricle myocardium. However, this dysfunction is reversible in most cases of TTC. Takotsubo syndrome affects predominantly postmenopausal females, typically with a direct link to emotional or physical stress factors. The pathophysiology of TTC remains unclear. In this study, we aimed to assess the pathophysiology of TTC using the invasive functional testing of coronary microcirculation. Methods Ten female patients diagnosed with TTC in line with interTAK Diagnostic Criteria were included in this pilot study. In all subjects we measured fractional and coronary flow reserve in the left anterior descending and left circumflex coronary arteries (FFR LAD, FFR LCx, CFR LAD, CFR LCx), and the index of microcirculatory resistance in the same arteries (iMR LAD, iMR LCx) in addition to acute and late (after 12 weeks) transthoracic echocardiography (TTE) and acute cardiac biomarkers (troponin and NT-proBNP). The results of the microcirculatory assessment were statistically compared with normal population values. Results In all subjects, the troponin level was elevated in the acute phase and repeated TTE revealed transient dysfunction of the left myocardial ventricle. Whilst fractional flow reserve was normal in both assessed epicardial artery territories for all patients (mean FFR LAD: 0.92±0.04; mean FFR LCx: 0.98±0.046), both mean values of coronary flow reserve disclosed pathological microcirculatory findings (CFR LAD: 1.9±1.197; CFR LCx: 1.75±0.742) and were pathological in nine out of ten subjects. Index of microcirculatory resistance revealed abnormal values in five out of ten patients for LAD (31.03±18.515) and three out of ten for LCx (23.8±17.86). Conclusions Our pilot study confirmed non-obstructive findings in the epicardial coronary arteries assessed by FFR. On the other hand, the investigation of both CFR and iMR, microcirculatory functional testing, revealed pathological findings in a significant number of evaluated subjects. From this aspect, our study validates further research in the field of microcirculatory functions as a possible mechanism in the origin of TTS. Acknowledgement/Funding Supported by MH CZ - DRO (FNBr, 65269705)