Main findings
A total of 1,604 publications were identified, and 1,225 were screened
after excluding duplicates. Twenty full-text articles were assessed for
eligibility after 1,205 were excluded with abstract and title screening.
After the assessment of full-text articles, 10 publications were
excluded for: no LBBP group data separately reported from HBP/CSP group,
no human study, published study protocol without data, and no control
group with BVP. Ten studies (9 observational studies and 1 randomized
controlled trial) were included (Figure 1).
The included studies comprised 616 patients across 15 centers, enrolled
from December 2012 to June 2021, with the median being 2019 (Table 1).
Patient baseline characteristics were reported in all studies (Table 2).
Left ventricular ejection fraction (LVEF) improvement was reported in
all 10 studies. Compared to BVP, LBBP was associated with greater
improvement (MD 5.80, 95% CI 4.81-6.78, I2=0%,
P<0.01, percentage) at the end of follow-up period. Left
ventricular end-diastolic diameter (LVEDD) reduction was also higher in
the LBBP group (MD 2.11, 95% CI 0.12-4.10, I2=18%,
P=0.04, millimeter). There was a greater improvement in New York Heart
Association function (NYHA) class with LBBP (MD 0.37, 95% CI 0.05-0.68,
I2=61%, P=0.02). Figure 2.
A composite outcome of heart failure-related hospitalization (HFH) and
all-cause mortality was also lower with LBBP compared to BVP CRT [Risk
ratio (RR) 0.48, 95% CI 0.25-0.90, I2=0%, p=0.02]
driven mainlyby heart failure hospitlizations (HFH) reduction (RR 0.39,
95% CI 0.19-0.82, I2=0%, p=0.01). However, all-cause
mortality rates were low in both groups (1.52% vs. 1.13%) and similar
(RR 0.98, 95%CI 0.21-4.68, I2=0%, p=0.87). Figure 3.