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 Table 1 – Demographic and clinical characteristic of study participants Characteristics Total (n = 71) LV Group (n = 35) RV Group (n= 36) p Female sex, n (%) 37 (52.1) 19 (54.3) 18 (50.0) 0.717 (1) Age (years), average ± SD 66.5 ± 11.2 68.4 ± 9.2 64.8 ± 12.8 0.179 (2) White race, n (%) 49 (69.0) 24 (68.6) 25 (69.4) 0.936 (1) Functional Class (NYHA), n (%) I 22 (31.0) 12 (34.3) 10 (27.8) II 33 (46.5) 15 (42.9) 18 (50.0) 0.544 (1) III 14 (19.7) 8 (22.9) 6 (16.7) IV 2 (2.8) - 2 (5.6) Structural cardiac disease, n (%) None 52 (73.2) 25 (71.4) 27 (75.0) Chagas disease 12 (16.9) 9 (25.7) 3 (8.3) 0.063 (3) Ischemic heart disease 6 (8.5) 1 (2.9) 5 (13.9) Hypertrophic cardiomyopathy 1 (1.4) - 1 (2.8) Associated comorbidities None 2 (2.8) 1 (2.9) 1 (2.8) 1.000 (3) Hypertension 59 (83.1) 28 (80.0) 31 (86.2) 0.492 (1) Chagas disease 8 (11.3) 5 (14.3) 3 (8.3) 0.710 (3) Diabetes 19 (26.8) 10 (28.6) 9 (25.0) 0.734 (1) Dyslipidemia 23 (32.4) 10 (28.6) 13 (36.1) 0.497 (1) Cardiovascular medications, n (%) None 4 (5.6) 2 (5.7) 2 (5.6) 1.000 (3) ACEI/ARB 52 (73.2) 28 (80.0) 24 (66.7) 0.204 (1) Diuretics 29 (40.8) 12 (34.3) 17 (47.2) 0.267 (1) Betablockers 8 (11.3) 6 (17.1) 2 (8.3) 0.151 (3) QRS duration prior to implant > 120 ms, n (%) 53 (74.6) 26 (74.3) 27 (75.0) 0.944 (1) LV ejection fraction, average ± SD 59.9 ± 6.8 61.1 ± 4.4 58.1 ± 8.4 0.069 (2) LV final systolic volume, average ± SD 42.1 ± 16.1 39.5 ± 15.4 44.8 ± 16.5 0.168 (2) LV final diastolic volume, average ± SD 100.7 ± 24.7 97.1 ± 27.2 104.3 ±21.7 0.223 (2) BNP, average ± SD 83.2 ± 111.8 72.3 ± 77.6 93.8 ±137.6 0.482 (2) TNF alpha, average ± SD 50.7 ± 186.6 74.9 ± 265.1 27.2 ± 13.5 0.388 (2) IL6, average ± SD 11.3 ± 16.0 9.1 ± 12.4 13.4 ± 18.8 0.092 (2) ACEI: angiotensin converting enzyme inhibitors; ARB: angiotensin receptor blockers; LV: left ventricle; NYHA: New York Heart Association; RV: right ventricle; SD: standard devition. (1) Chi-squared test; (2) Unpaired Student’s t-test; (3) Fisher’s exact test. There were no hospitalizations due to heart failure during the study’s follow-up period. At the end of the first month of observation, 100% of the patients in the RV Group and 97.1% in the LV Group were oligosymptomatic, being classified as in functional class (FC) I or II. The analysis of Figure 4 shows that there was no difference in behavior between the groups throughout the follow-up period. Few patients presented symptoms with minor exertion and were classified as FC III. No cases were classified as FC IV. Echocardiographic results The echocardiographic studies performed at the baseline and at month 24 of follow-up showed that there was left ventricular remodeling and changes in ejection fraction over time in both groups. They also showed the presence of differences in the mechanics of the two ventricles resulting from right or left ventricular pacing. The analysis in Table 3 makes it possible to observe that: (1) a reduction of more than 10% in LV ejection fraction was observed in 23.5% of the patients in the RV group and in 20.6% of the LV Group (p = 0.767); (2) an increase of more than 15% in final systolic volume was observed in 27.3% of the individuals in the RV Group and 29.4% in the LV Group (p = 0.846), and that both outcomes occurred at the same time in 32.3% of the RV Group and 35.3% of the LV Group (p = 0.798). 415