IJCS | Volume 31, Nº3, May/ June 2018

269 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 Table 5 - Statistical analysis of the pre and post- implantation resynchronizer findings between scintigraphy and echocardiography parameters, using Student’s t-test, considering p values < 0.05 as statistically significant Scintigraphy Pre- implantation Post- implantation p value Ejection fraction, % 29.4 33.89 0.32 End-diastolic volume, mL 293.7 231.1 0.08 End-systolic volume, mL 206.2 158 0.05 Mass, g 249 193.9 0.02 PP 116 114 0.94 SD 53.66 45.8 0.53 HBW 143.8 130.3 0.68 S 2.78 3.28 0.27 K 7.38 15. 35 0.17 PP: peak phase; SD: standard deviation; HBW: histogram bandwidth. QRS (ms) SD (degrees) Correlation QRS duration x SD y = 0.3665x - 27.378 R 2 = 0.07871 Figure 1 - Correlation between pre-implantation QRS duration and pre-implantation standard deviation (SD). The us e o f imag i ng me t hods t o i den t i f y desynchronization has been validated; 16 however, its routine use as a support tool for the selection of patients for CRT remains a topic to be studied, such as the study of Henneman et al., 21 who evaluated patients with CRT indication through GSPECT and observed a 29% rate of nonresponders after 6 months of therapy – comparable to the 22% observed in the present study. In the study by Henneman et al., 21 the responders had significantly higher dyssynchrony parameters compared to non-responders (HBWof 175° vs. 117°; and SD of 56° vs. 37°, respectively). These values ​are close to those found in our results (HBW of 177° vs. 76° and SD of 62° vs. 36°, respectively), confirming that the presence of MD identified at GSPECT is a strong predictor for CRT response. 21 Henneman et al. 21 derived, from the sample of 42 patients, cut-off values​ of the scintigraphic parameters to indicate the presence of MD and to predict good response to CRT in patients with HF: HBW > 135° and SD > 43°. 21 Medical therapy decision-making should always focus on treatments that lead to changes in clinical outcomes, rather than just changes in imaging or laboratory tests. Thus, more than ventricular function improvement, the aim of this study was to select an ideal patient, who shows a reduction in morbidity and mortality after CRT. Recent studies have demonstrated that the phase analysis parameters are markers of adverse prognosis, as observed by Al Jaroudi et al., 22 who evaluated 144 patients with chronic renal failure and had higher mortality at 2 years in those with HBW ≥ 62° − a value well below that of the study by