Bundle branch block
There were 50 patients with BBB, 27 with RBBB, and 23 with LBBB. The overall success rate was 84% (n = 42), with no significant difference (P  = .25) between HBP (76.9%) and LBBAP (91.7%) groups. QRS narrowing was achieved in all patients with BBB except for two patients with no change in QRS width. A paced QRS >120 ms was more frequent in the HBP group (60% vs. 18.2%; P  < .01).
Among the patients with LBBB (12 in HBP and 11 in LBBAP), the success rate was close-to-significantly higher in the LBBAP group (100% vs. 66.7%; P  = .09). Among successful cases, the paced QRS width was lower in the LBBAP group (112 ± 9 vs. 127 ± 26 ms; P  = .16), although the difference did not reach statistical significance, and the QCI (QRS narrowing) was similar between HBP (–32.2 ± 13%) and LBBAP (–34.8 ± 4.8%) groups (P  = .59). Among the patients with RBBB (14 in HBP and 13 in LBBAP), the success rate did not differ between HBP (85.7%) and LBBAP (84.6%) groups (P  = 1), but the paced QRS width was lower (106 ± 7 vs. 122 ± 16 ms; P  < .01) and the QCI was close-to-significantly higher (–31 ± 10% vs. –21 ± 14%;P  = .09) in the LBBAP group.