IJCS | Volume 31, Nº3, May/ June 2018

268 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 3 - Scintigraphic parameters of the pre-implantation synchronization of the resynchronizer Patient PP SD HBW S K 1 110 61.08 171 2.96 9.34 2 118 74.04 160 4.09 5.15 3 105.5 22.41 58.5 3.15 10.37 4 153 46.77 146 2.36 5.54 5 191.5 57.74 203 2.31 6.00 6 109 49.26 129 2.99 11.83 7 44.5 15.91 35.5 3.32 10.27 8 131.5 85.71 257 2.09 5.13 9 81 69.93 134.5 1.72 2.82 Mean ± SD 116 ± 39 53 ± 21 144 ± 64 2.7 ± 0.7 7.4 ± 3 PP: peak phase; SD: standard deviation; HBW: histogram bandwidth; S: skewness; K: Kurtosis; SD: standard deviation. Table 4 - Clinical response before and after cardiac resynchronizer implantation Variables Pre-resynchronization Post-resynchronization p value NYHA Functional Class II 2 7 III-IV 7 2 0.015* MLHFQ 63.6 ± 17.5 34.1 ± 20.5 0.006† 6-minute Walk Test Distance covered, m 342.7 ± 82.2 376.6 ± 84.0 0.314** Borg index 3.1 ± 1.8 1.2 ± 1.3 0.023† Dyspnea 2.4 ± 2.0 0.89 ± 0.93 0.049† Fisher's exact test; † paired t-test. MLHFQ: Minnesota Living with Heart Failure Questionnaire. with phase analysis, as well as the fact that it can be used in patients with HF and CRT indication. The pathophysiological basis for the resynchronizer implantation is the correction of a mechanical disorder secondary to an altered LV activation due to LBBB. The presence of LBBB is a sign of electrical abnormality and has been the main criterion for the selection of patients to undergo CRT. 17 However, the current criteria used to indicate CRT are still imperfect, as a group of 20 to 40% of patients does not respond to treatment. 18,19 Bleeker et al. 20 compared the echocardiogramwith QRS duration for MD evaluation, and found that 30 to 40% of the patients with QRS duration > 120 ms did not have mechanical desynchronization, suggesting that there is an association between the findings of non-response to CRT and absence of MD. 20 MD was not necessarily associated with ED, as evidenced by the absence of MD in patients with QRS duration > 120 ms. 20 This finding was also demonstrated in the present study, in which 22% of patients with clinical indication for CRT (and QRS duration > 150 ms) did not show electrocardiographic criteria for MD. These patients didnot showclinical improvement after CRT implantation.