IJCS | Volume 31, Nº3, May/ June 2018

271 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 Study limitations The main study limitation was the small number of patients, which limited the statistical analysis. Despite the small sample size, statistical significance was observed in parameters that corroborate previous studies in the dyssynchrony area. Another study limitation was the absence of a control group with ventricular dysfunction without CRT. From the ethical point of view, it is not possible to maintain patients with CRT indication as controls, considering the impact of this treatment on mortality and its broad indication recommended in several guidelines. 6 The study had a short follow-up period (6 months) using secondary outcomes, such as left ventricular function, rather than clinical outcomes such as death, HF progression or hospitalization. Conclusion The study of phase analysis by GSPECT was able to differentiate patientswith isolated electrical dyssynchrony from those with associated mechanical dyssynchrony, through the intraventricular dyssynchrony parameters. The cardiac resynchronization therapy is associatedwith theimprovementofboththemechanicaldesynchronization (improvement of desynchronization parameters through the phase analysis) and electrical dyssynchrony (QRS interval reduction at the electrocardiogram). Thus, because of the pre-implantation GSPECT assessment, it was possible to verify that patients with associated electrical and mechanical dyssynchrony showed better response to cardiac resynchronization therapy than those with isolated electrical dyssynchrony. Acknowledgments To Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) and the International Atomic Energy Agency that funded this study. Author contributions Conception and design of the research: Wiefels CC, Nascimento EA, Alves CR, Ribeiro FB, Ribeiro ML, Mesquita CT. Acquisition of data: Wiefels CC, Nascimento EA, Alves CR, Ribeiro FB, Fernandes FA, RibeiroML, Mesquita CT. Analysis and interpretation of the data: Wiefels CC, Nascimento EA, Alves CR, Ribeiro FB, Fernandes FA, Ribeiro ML, Mesquita CT. Statistical analysis: Wiefels CC, Nascimento EA, Alves CR, Mesquita CT. Obtaining financing: RibeiroML, Mesquita CT. Writing of the manuscript: Wiefels CC, Nascimento EA, Alves CR, Ribeiro FB, Fernandes FA, Ribeiro ML, Mesquita CT. Critical revision of the manuscript for intellectual content: Wiefels CC, Mesquita CT. Potential Conflict of Interest No potential conflict of interest relevant to this article was reported. Sources of Funding This study was partially funded by Agência Internacional de Energia Atômica. Study Association This article is part of the thesis of master submitted by Christiane Cigagna Wiefels, from Universidade Federal Fluminense. Ethics approval and consent to participate This study was approved by the Ethics Committee of the Hospital Universitário Antônio Pedro under the protocol number 884.844. All the procedures in this study were in accordance with the 1975 Helsinki Declaration, updated in 2013. Informed consent was obtained from all participants included in the study. 1. Hunt SA, Abraham WT, Chin MH, Feldman AM, Francis GS, Ganiats TG, et al. 2009 focused update incorporated into the ACC/AHA 2005 Guidelines for the Diagnosis andManagement of Heart Failure inAdults: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines: developed in collaboration with the International Society for Heart and Lung Transplantation. Circulation. 2009;119(14):e391-479. 2. Mozaffarian D, Benjamin EJ, Go AS, Arnett DK, Blaha MJ, Cushman M, et al; American Heart Association Statistics Committee; Stroke Statistics Subcommittee. Heart disease and stroke statistics 2016 Update: AReport From the American Heart Association. Circulation. 2016;133(4):e38-360. 3. Albuquerque DC, Souza JD, Bacal F, Rohde LE, Bernardez-Pereira S, Berwanger O, et al; Investigadores Estudo BREATHE. I Brazilian Registry of Heart Failure - clinical aspects, care quality and hospitalization outcomes. Arq Bras Cardiol. 2015;104(6):433-42. 4. Wells G, Parkash R, Healey JS, Talajic M, Arnold JM, Sullivan S, et al. Cardiac resynchronization therapy: a meta-analysis of randomized controlled trials. CMAJ. 2011;183(4):421-9. References