ABC | Volume 112, Nº4, April 2019

Original Article Philbois et al Isolated left ventricular pacing in bradyarrhythmias Arq Bras Cardiol. 2019; 112(4):410-421 Figure 2 – View of the active-fixation coronary sinus lead (Medtronic Attain StarFix ® Model 4195 OTW). Electronic data collection and management Demographic, clinical, surgical, and echocardiographic data were collected and stored in an electronic database developed in REDCap ( Research Electronic Data Capture ) System, 34,35 which is hosted on our institution’s server. Statistical analysis The data registered in the REDCap System were exported in the form of Excel spreadsheets (Microsoft Excel) and analyzed by the Statistical Package for the Social Sciences (SPSS), version 17.0. All variables were initially analyzed descriptively. For quantitative variables, this analysis was done by observing the minimum and maximum values, the averages, and standard deviations. Absolute and relative frequencies were calculated for all qualitative variables. We used unpaired Student’s t- test to compare averages between groups; when the normality assumption of the data was rejected, the variable was evaluated by logarithmic transformation. The chi-squared test or Fisher’s exact test was used to test homogeneity between proportions. We used Analysis of Variance with repeated measures to compare groups throughout the evaluations. Data analysis was performed according to the intention- to-treat principle. The level of significance for statistical tests was set at 5%. Results Participants In the period between June 2012 and January 2014, 417 patients were indicated for conventional PM implantation due to bradyarrhythmias and were, thus, potential candidates for participation in this study. Of these, 91 were included in the study (Figure 3). Patient inclusion was prematurely interrupted by a consensual decisionmade by the study’s monitoring committee due to problems related to safety of using the Medtronic Attain StarFix ® Model 4195 OTW lead. Following this decision, no other participants were included. Nonetheless, clinical follow-up continued until the last patient, who was included in January 2014, had completed 24 months of postoperative follow-up. The premature interruption of this study occurred due to difficulties in obtaining adequate left ventricular pacing conditions with the operating technique defined in the research protocol, on the part of the study population. Demographic and basic clinical characteristics The population included in this study was composed of 71 individuals who participated in all phases of the study. There was a slight predominance of females (52.1%), as well as individuals who self-identified as white (69.0%). At the moment of inclusion, average age was 66.5 ± 11.2 years, varying from 24 to 85 years of age. Demographic and clinical characteristics were similar in both groups, except for the presence of Chagas disease, which was more common in the LV Group (Table 1). Characteristics of the operation Atrioventricular PMwere implanted in 95.8% of individuals studied. Single-chamber ventricular pacing was indicated in 3 (4.2%) patients as a consequence of permanent atrial fibrillation. Details regarding surgical procedures performed on patients in the RV and LV Groups are shown in Table 2. Data comparison related to the operations performed to implant the devices used in this study revealed significant differences between the groups. Time spent implanting left ventricular leads was, on average, 32.4 minutes greater than RV lead implant. Moreover, the total duration of the procedure was also longer, lasting, on average, 36.3 minutes more in patients in the LV Group. The approach used to introduce the leads also differed significantly between the two groups. In patients allocated to the LV Group, cephalic vein dissection, either isolated or in association with one puncture in the subclavian vein, was more frequent. The analysis in Table 2 shows that two punctures of the subclavian vein was the preferred technique for the patients in the RV Group (p = 0.002). 413