Background:While cardiac resynchronization therapy is effective in dyssynchronous heart failure, suboptimal response remains frequent. The acute hemodynamic profile of different left bundle‐branch (LBB) area pacing modalities is poorly defined. Moreover, atrioventricular optimization guided by QRS duration (QRSd) may not yield the greatest hemodynamic benefit.
Methods:Twenty‐four patients with heart failure, reduced ejection fraction, and LBB block underwent sequential testing of right ventricular septal pacing, left ventricular septal pacing, nonselective LBB pacing, and selective LBB pacing during cardiac resynchronization therapy implantation in a prospective, within‐subject physiological study. At each modality, electrical end points were QRSd and vectorcardiographic QRS area; hemodynamics were assessed with beat‐to‐beat systolic blood pressure (SBP). The atrioventricular interval producing maximal SBP improvement was compared with that producing the narrowest QRSd.
Results:LBB area pacing
modalities significantly reduced
QRSd
, compared with right ventricular septal pacing (nonselective
LBB pacing,
114.0±16.8 milliseconds; selective
LBB pacing
, 118.4±14.1 milliseconds; left ventricular septal pacing, 124.6±16.0 milliseconds; right ventricular septal pacing, 144.4±27.6 milliseconds; all
P
<0.01). At the
atrioventricular
interval that produced maximized
SBP
improvement,
QRSd
remained narrower with
LBB area pacing
than right ventricular septal pacing, and selective
LBB pacing
provided the greatest hemodynamic improvement (
ΔSBP
16.3±5.2
mm Hg
), exceeding left ventricular septal pacing (13.5±6.2
mm Hg
) and nonselective
LBB pacing
(12.8±6.3
mm Hg
; all
P
<0.05). Across modalities, the
atrioventricular
interval that maximized
ΔSBP
was consistently shorter than that minimizing
QRSd
(mean difference, 18–29 milliseconds).
Conclusions:Selective LBB pacing yields the greatest acute hemodynamic benefit, and the hemodynamic‐optimal atrioventricular interval is shorter than the electrical‐optimal atrioventricular interval, suggesting that modest atrioventricular interval shortening after electrical optimization may better maximize hemodynamics.
Registration:
URL:
https://www.clinicaltrials.gov
; Unique Identifier: NCT07032064.