Comparing left-ventricular-only and biventricular pacing for smarter synchronization
A Spadotto, G Martini, A Carecci, A Angeletti, G Massaro, L Bartoli, C Martignani, I Diemberger, M Ziacchi, G Statuto, M BiffiAbstract
Background
Biventricular pacing (BiV) is the standard CRT strategy for HFrEF with ventricular dyssynchrony. However, left-ventricular-only pacing (LV-only) has been used as an alternative, with growing similar, and in some cases possibly greater, clinical benefit.
Purpose
To compare BiV versus LV-only pacing in patients with left bundle branch block (LBBB) undergoing CRT, assessing left-ventricular reverse remodeling at 12 months and clinical outcomes (all-cause mortality and major adverse cardiac events, defined as death, HF hospitalization, LVAD implantation, or heart transplantation).
Methods
This single-center, prospective observational study enrolled consecutive patients with HFrEF and LBBB undergoing CRT implantation from 2018 to 2023, excluding those with permanent AF, NYHA IV symptoms, pregnancy, dialysis, or prior devices requiring upgrade. All patients underwent baseline clinical, ECG, and echocardiographic evaluation, with repeat assessment at one year per routine practice. LV-only strategy was considered after implantation when PR interval was < 260 ms, and consisted of fusion with intrinsic conduction via the right bundle. Patients were classified as LV-only when ≥85% of pacing time was delivered to the left ventricle.
Results
A total of 135 patients were enrolled (mean age 66.8 ± 11.5 years; 64% male; baseline LVEF 29.6 ± 6.2%). Of these, 56 received BiV pacing and 79 achieved LV-only pacing. Baseline characteristics were comparable between the two groups in terms of age, sex, LVEF, and ventricular volumes. As expected, the PR interval was shorter in the LV-only cohort, although this difference did not reach statistical significance (BiV 196 ± 50.5 ms vs. LV-only 184 ± 31.1 ms; p = n.s.). At 12-month echocardiographic follow-up, both groups demonstrated significant reductions in LV end-systolic and end-diastolic volumes; however, reverse remodelling was more pronounced in the LV-only group. LVEF improved significantly from baseline in both cohorts, with no significant between-group difference. Using ≥15% reduction in ESV as a response criterion, 90% of LV-only patients were CRT responders versus 73% in the BiV group (p = 0.02) (Table 1). Annual all-cause mortality was 3.8%, with no difference between groups in mortality or major adverse cardiac events (Figure 1). The initial pacing strategy remained stable over time, with a low rate of cross-over (6.2%) equally distributed between groups.
Conclusion
In selected LBBB patients eligible for cardiac resynchronization therapy, LV-only pacing represents a therapeutic strategy that is at least equivalent to conventional BIV pacing. It may therefore enhance device longevity, and represents the benchmark for emerging resynchronization modalities, such as conduction-system pacing, in patients with preserved atrioventricular conduction owing to its ability to maintain physiological activation via fusion with intrinsic conduction.Table 1