CLINICAL RESEARCH CORONARY INTERVENTIONS © Europa Digital & Publishing 2018. All rights reserved. *Corresponding author: Cardiovascular Science Division of the NHLI within Imperial College of Science, Technology and Medicine, South Kensington Campus, London, SW7 2AZ , United Kingdom. E-mail: patrick.w.j.c.serruys@gmail.com Intracoronary electrocardiogram to guide percutaneous interventions in coronary bifurcations – a proof of concept: the FIESTA (Ffr vs. IcEcgSTA) study Dobrin Vassilev 1 , MD, PhD; Liubomir Dosev 1 , MD; Carlos Collet 2 , MD; Kiril Karamfiloff 1 , MD, PhD; Jivka Stoikova 1 , MD, PhD; Ralica Pancheva 1 , MD; Monika Shumkova 1 , MD; Galina Zlatancheva 1 , MD; Vladimir Naunov 1 , MD; Gianluca Rigatelli 3 , MD; Ghassan S. Kassab 4 , PhD; Robert J. Gil 5 , MD, PhD; Patrick W. Serruys 6 *, MD, PhD 1. “Alexandrovska” University Hospital, Cardiology Department, Medical University, Sofia, Bulgaria; 2. Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands; 3. Section of Cardiovascular Diagnosis and Endoluminal Interventions, Rovigo General Hospital, Rovigo, Italy; 4. California Medical Innovations Institute, San Diego, CA, USA; 5. Department of Invasive Cardiology, Central Clinical Hospital of the Ministry of Interior, Warsaw, Poland; 6. Imperial College London, London, United Kingdom D. Vassilev and L. Dosev contributed equally to this manuscript. GUEST EDITOR: Adrian Banning, MB, BS, FRCP, MD; Oxford Heart Centre, Oxford University Hospital, Oxford, United Kingdom Abstract Aims: The aim of this study was to determine the accuracy of the intracoronary electrocardiogram (icECG) to detect ischaemia during bifurcation lesion percutaneous coronary intervention (PCI) with fractional flow reserve (FFR) as a reference. Methods and results: Patients with significant bifurcation lesions defined as FFR ≤0.80 were included. FFR and icECG were performed in the main vessel (MV) and side branch (SB) before and after provisional stenting. icECG was recorded with an uninsulated proximal wire end connected to a unipolar lead. The diagnostic accuracy of the icECG for the detection of ischaemia in the SB after MV stenting was deter- mined with FFR as a reference. Overall, 37 patients were included. Seventeen bifurcations had an SB FFR ≤0.80 after MV stenting and 20 patients had an ST-segment elevation on the icECG. There was significant correlation between SB FFR and ST-segment elevation on the icECG (r= –0.533, p<0.001). The diagnos- tic accuracy of icECG ST-elevation to detect functionally significant SB stenosis revealed an AUC of 0.71 (95% CI: 0.64-0.80) with a sensitivity of 88% and specificity of 75% with a positive predictive value of 75% and negative predictive value of 88%. Neither SB FFR nor icECG correlated with SB percent diameter stenosis after MV stenting. Conclusions: Intracoronary ECG has a good ability to predict functionally significant stenosis at the SB after MV stenting during bifurcation PCI. This method provides a novel strategy to assess the significance of an SB lesion without the need of a pressure wire. ClinicalTrials.gov Identifier: NCT01724957 KEYWORDS • bifurcation • drug-eluting stents • fractional flow reserve e 530 EuroIntervention 2018;14: e 530- e 537 published online August 2017 published online e -edition August 2018 DOI: 10.4244/EIJ-D-17-00189 SUBMITTED ON 09/03/2017 - REVISION RECEIVED ON 1 st 23/06/2017 / 2 nd 09/08/2017 - ACCEPTED ON 15/08/2017