IJCS | Volume 32, Nº5, September/October 2019

498 Cont. Table 4 - Comparison of characteristics of patients who were discharged with and without permanent pacemaker 33 patients were discharged without permanent pacemaker 16 patients had permanent pacemaker implanted while in hospital Odds ratio (95% CI), p value Variables related to the implant: CoreValve ® implant 21/33 (63.6%) 16/16 (100%) 1.76 [1.33 - 2.33] p = 0.005 2 nd valve required 3/33 (9.1%) 4/16 (25%) 0.195 Femoral access 27/33 (81.8%) 15/16 (93.8%) 0.401 Prosthesis size in mm 26.87 ± 2.50 28.56 ± 1.96 IQR: interquartile range; LBBB: left bundle branch block; RBBB: right bundle branch block; LAHB: left anterior hemiblock; LPHB: left posterior hemiblock; AVB: atrioventricular block. Cedenilla et al. Requirements for permanent pacemaker afterTAVI Int J Cardiovasc Sci. 2019;32(5):492-504 Original Article The CoreValve ® implant was associated with the pacemaker implant in a statistically significant way in the univariate analysis (odds ratio: 1.76; (95% CI: 1.33 to 2.33; p = 0.005). All patients undergoing permanent pacemaker implantation were CoreValve ® patients. Larger prostheses were also associated with a greater need for permanent pacemaker implantation (Table 4). In the multivariate analysis, the only variable considered to be an independent predictor of the need for pacemaker implantation after TAVI was the presence of first-degree AVB before implantation of the prosthesis. (Odds ratio: 13.00; 95% CI 1.95 to 86.80; p = 0.008). Survival of patients undergoing TAVI: Median follow-up of the 53 patients undergoing TAVI was 363 days with an interquartile range of 86.5 to 755.5 days. During this follow-up, 13 (24.5%) died (4 during index admission and 9 at outpatient follow-up). Eight of the 9 patients who died during follow-up had either LBBB or permanent pacemaker. The survival of patients who did not develop new conduction disorders was higher than those with new conduction disorders, but this result was not statistically significant (p = 0.26). (Figure 2) Nineteen (35.8%) of the 53 patients had pacemakers implanted throughout the study (16 during index admission and 3 at outpatient follow-up). Pacemaker-free survival was significantly lower in the group of patients who had CoreValve ® implanted, in patients who had first-degree AVB before TAVI and in those with QRS complex greater than 120 ms before TAVI. Pacemaker- free survival was also lower in patients who had RBBB prior to TAVI. This result was not statistically significant (p = 0.08) (Figures 3 and 4). Discussion The benefits of TAVI include: improved functional class and quality of life, increased ejection fraction and increased short- and long-term survival. 9-12 Despite some favorable clinical outcomes, complications such as the development of LBBB and AVB requiring pacemakers are a source of concern. The high incidence of conduction disorders after TAVI can be explained by the anatomical proximity of the conduction system to the aortic valve. 32 TAVI involves the exclusion of valve tissue by the prosthesis and compression of the annulus and adjacent structures, including the fibrous skeleton of the heart and the conduction system. A necropsy study of a patient who had CAVB after TAVI demonstrated the presence of a hematoma in the interventricular septum that compressed the bundle of His. 33 In this study, 77% of the patients developed new conduction disorders during index admission. These findings are identical to those described by Fraccaro et al. in 64 patients undergoing TAVI, 24 and very similar to those described in the studies by Calvi et al., who found new conduction disorders in 68% of the 30 patients who underwent the procedure. 23 In this study, it was found that 30.7% of the patients developed LBBB. This finding is similar to that described by Houthuizen et al., who found a new LBBB in 34% of the 679 patients who underwent TAVI. 25 The incidence of LBBB after TAVI can range from 4 to 65% depending on the prosthesis used. According to Martinez et al., the frequency of a new LBBB after the