IJCS | Volume 31, Nº3, May/ June 2018

270 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 Figure 2 - Distribution of mean SD and HBW before implantation of the cardiac resynchronization therapy, according to the clinical response to implantation. *Chi-square test, with p = 0.03. non-responder responder Henneman et al., 21 but already showing some degree of desynchronization. The subgroup of patients with end-stage renal disease was also extensively studied by Aggarwal et al., 23 who followed 828 patients with normal EF for 5 years. It was observed that values ​of SD ≥ 21° or HBW ≥ 56° were associated with worse survival in 5 years. Thus, they also demonstrated that LV desynchronization through phase analysis (GSPECT) provides prognostic value in end-stage renal failure. 23 A relatively recent study by Zafrir et al. 24 had a significant impact on desynchronization assessment and its association with cardiac mortality, by following 787 patients who underwent GSPECT in a single center for several clinical reasons. 24 These patients were followed for 18.3 ± 6.2 months for cardiac events, and it was verified that SD had the capacity to predict cardiac mortality, and that with every 10° increment, it became an independent predictor of mortality (p = 0.04). Our study did not have data on adverse clinical outcomes in the long term, but ventricular function improvement has been used in several situations, as a valuable surrogate outcome. Studying clinical outcomes specifically in patients with HF, Al Jaroudi et al. 22 assessed dyssynchrony in patients with an implantable cardioverter defibrillator (ICD) and showed that the higher the SD and the HBW, the higher the incidence of cardiopulmonary arrest or appropriate shock by the ICD. 23 The value of SD > 50° was a predictor of death or appropriate shock by the ICD. More recently, Zafrir et al., 24 assessing 143 patients with HF and ICD indication, showed a higher rate of events when they also had DM evidenced by SD > 60°. 25 These authors suggest that patients referred to a defibrillator implantation should receive associated CRT when they have SD > 60°. 25 New studies have addressed the combination of GSPECT parameters to create a MD gradation, using, in addition to HBW and SD, the K and S parameters. Aguadé-Bruix et al. 26 employed a combination of these four parameters and observed that 12% of patients with CRT indication do not have any abnormal phase parameters 26 . Perhaps the study of these combined parameters can increase the sensitivity and specificity of the technique for CRT indication. In summary, the findings of the present study, together with the growing literature in the area, support that phase analysis by GSPECT is considered a clinically useful tool, to be used both in the assessment of patients in specific subgroups of high cardiovascular risk (end-stage chronic renal failure, hypertensive patients, patients with ICDs) and in the selection of patients with CRT indication.