IJCS | Volume 31, Nº3, May/ June 2018

265 Wiefels et al. Evaluation of Desynchronization with GSPECT in Patients with Heart Failure International Journal of Cardiovascular Sciences. 2018;31(3)264-273 Original Article Failure (BREATHE) has shown that 60% of the cases admitted to hospitals with HF are due to a reduction in the left ventricular systolic function. 3 The cardiac resynchronization therapy (CRT) comprises an implantable device capable of synchronic stimulation of the left ventricle (LV) walls, improving cardiac performance and ejection fraction (EF). It has shown to be effective in restoring the synchronic contraction of the interventricular septum with the LV posterolateral wall, contributing to a reduction inneurohumoral activation and consequent reverse remodeling. 4 CRT is awell-established treatment for morbidity and mortality reduction in HF. 5 ThecurrentcriteriaforCRTimplantation,recommended by the European Society of Cardiology 6 with Class I and Level of Evidence A for CRT implantation, are: NewYork Heart Association (NYHA) functional class II and III with sinus rhythm, LVEF < 35%, QRS width > 150 ms or 120 to 150 ms with Ventricular Electrical Dyssynchrony (ED) by Left Bundle Branch Block (LBBB). Despite the benefit observed with the use of CRT, there is still a high rate of nonresponders (between 20 and 40%). 7-11 Patientswith coronary artery disease and patients with acute myocardial infarction (AMI) are less likely to show a good response to the resynchronizer implantation and a lower chance of undergoing reverse remodeling. 12 Therefore, it becomes necessary to improve patient selection for CRT, considering not only the ED criteria, which would be QRS enlargement (> 150 ms) and LBBB, but also the presence of mechanical desynchronization (MD), according to scintigraphic criteria. The aim of our study was to assess the clinical and scintigraphic responses of patients with HF submitted to CRT using the phase analysis based on the gated-Single Photon Emission Computed Tomography (GSPECT). Methods We performed a prospective intervention study that included consecutive patients (age > 18 years) according to the following inclusion criteria: NYHA functional class II to IV, despite receiving optimal medical treatment according to the guidelines, 6 in sinus rhythm, LVEF < 35%, QRS width > 150 ms or 120 to 150 ms with ventricular dyssynchrony (presence of LBBB). Patients with CRT indication, who signed the Free and Informed Consent Form, were invited to participate in the study. The patients were referred from the Cardiology Outpatient Clinic ofHospital UniversitárioAntônio Pedro and the Electrophysiology Outpatient Clinic of Instituto Estadual de Cardiologia Aloysio de Castro. All patients were submitted to GSPECT within 4 weeks prior to CRT implantation and 6 ± 1 month after implantation for comparison. These patients also answered theMinnesota Living with Heart Failure Questionnaire (MLHFQ) and underwent a speckle-tracking echocardiography before and 6 months after implantation, to obtain the EF and end-systolic volume (ESV) variables, with all these evaluations being carried out in a single day, at Hospital Universitário Antônio Pedro. This study is part of a multinational research project, funded by the International Atomic Energy Agency, which evaluates the use of GSPECT in finding the best left ventricular segment for resynchronizer electrode implantation. This study is being carried out in several countries,aimingatfollowingpatientswithCRTindication. 12 Exclusion criteria were: death before completing the follow-up period; severe illness with risk of death in the following 6 months; acute coronary syndromes; CABG surgery or percutaneous coronary intervention in the 3 months before enrollment and within 6 months after CRT implantation. Patientswere submitted toGSPECTat rest in the supine position after intravenous administration of the 99mTc- sestamibi radiotracer (RPH, Brazil). The administered activity was 10 to 20 mCi (adjusted by weight 0.2 mCi/ kg). The waiting time between the injection and image acquisition was 40 to 60 minutes. Patients received fatty foods after the injection to minimize liver uptake. The Millenium MPR gamma-camera (GE, Milwaukee, USA)was used, and the imageswereprocessed through the Xeleris 3.0 workstation. Ventricular function analysis was performed using the Emory Cardial Toolbox™, version 3.0 2012 (Syntermed, USA), which generated values of LVEF, ventricular volume and LV mass. Quantitative analyses and image processing were performed using the SyncTool™ software, which was developed for the evaluation of LV MD by GSPECT. 13 The phase analysis technique can transform the four-dimension images (three spatial planes and time) into two-dimensional paired images. The computer program generates an analysis of the cardiac contraction sequence (phase). Each pixel of the cardiac images has its own cycle of contraction and relaxation, having a characteristic temporal association (phase) in relation to the R wave. Based on the phase histogram, the software calculates five quantitative indices: PP (Peak Phase), SD (Standard Deviation), HBW