4.2 LBBAP as a resynchronization strategy for HFmrEF
In this meta-analysis, during the average follow-up of 9.1 ± 3.8 months,
the mean decrease in QRS duration after LBBAP in patients with HFmrEF
was -34.51 ms (95% CI: -60.00– -9.02; P<0.01). The mean LVEF
increase was 10.9% (95% CI: 6.56–15.23, P<0.01), and the
NYHA functional status improvement was -0.8 (only one article,
P<0.01). This suggests that LBBAP is clinically beneficial for
resynchronization therapy in the treatment of HFmrEF.
Interestingly, both HFrEF and HFmrEF exhibited significant improvements
in LVEF after LBBAP. The LVEF attainment was 45.6% ± 7.9% for HFrEF
and 50.5% ± 3.9% for HFmrEF, suggesting that intervention with more
advanced cardiac remodeling before the LVEF reaches <35% may
be more beneficial.
Current findings reveal that about 30% of patients for whom CRT is
indicated are nonresponders.3,39,40 Moreover, among
several studies that evaluated the effect of CRT in midrange HF with an
LVEF >35%, CRT did not significantly increase the LVEF or
clinical composite score.34,41 Among these studies, it
is encouraging that the resynchronization strategy applied with
conduction system pacing—especially LBBAP, which overcomes some of the
limitations of HBP—showed significant improvement in LVEF in patients
with HFmrEF.