ABC | Volume 111, Nº4, Octuber 2018

Original Article Nascimento et al Electromechanical dyssynchrony and GATED SPECT in CRT Arq Bras Cardiol. 2018; 111(4):607-615 Figure 5 – Distribution of the mean pre-cardiac resynchronization therapy SD and HBW according to clinical response. SD: standard deviation; HBW: histogram bandwidth (Student t test). 250 150 50 0 200 100 SD HBW Nonresponder Responder Figure 6 – Response to cardiac resynchronization therapy according to the left ventricular lead implantation site. Post Lat - posterolateral region; Post Sep - posteroseptal region. 8 7 6 5 4 3 2 1 0 Lateral Post Lat Post Step Responder Non-responder Despite the limitation of LV lead positioning in the last activation site, the vascular technique has some benefits: 1. less invasive procedure with smaller peri- and postoperative complications; 2. lower chronic stimulation thresholds; and 3. shorter hospital length of stay. One strategy to overcome the limitation of stimulating the maximal delay site in LV contraction is the possibility of using multipoint pacing. This stimulation has been made possible with the development of technologies of multipolar leads that stimulate the left ventricle in several sites, generating several possibilities of stimulating vectors. 20 In addition, GATED SPECT can identify the last LV activation site at the same time it identifies if the area has fibrosis, contributing, thus, to select patients for CRT. Of the limitations of our study, we highlight the small number of patients assessed and the lack of quadripolar LV leads, which increase the likelihood of LV resynchronization as compared to the use of unipolar leads. 612