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Comparative Study
. 2018 Feb 6;7(3):e007489.
doi: 10.1161/JAHA.117.007489.

Programming Cardiac Resynchronization Therapy for Electrical Synchrony: Reaching Beyond Left Bundle Branch Block and Left Ventricular Activation Delay

Niraj Varma  1 , David O'Donnell  2 , Mohammed Bassiouny  3 , Philippe Ritter  4 , Carlo Pappone  5 , Jan Mangual  6 , Daniel Cantillon  3 , Nima Badie  6 , Bernard Thibault  7 , Brian Wisnoskey  6
Affiliations
Comparative Study

Programming Cardiac Resynchronization Therapy for Electrical Synchrony: Reaching Beyond Left Bundle Branch Block and Left Ventricular Activation Delay

Niraj Varma et al. J Am Heart Assoc. .

Abstract

Background: QRS narrowing following cardiac resynchronization therapy with biventricular (BiV) or left ventricular (LV) pacing is likely affected by patient-specific conduction characteristics (PR, qLV, LV-paced propagation interval), making a universal programming strategy likely ineffective. We tested these factors using a novel, device-based algorithm (SyncAV) that automatically adjusts paced atrioventricular delay (default or programmable offset) according to intrinsic atrioventricular conduction.

Methods and results: Seventy-five patients undergoing cardiac resynchronization therapy (age 66±11 years; 65% male; 32% with ischemic cardiomyopathy; LV ejection fraction 28±8%; QRS duration 162±16 ms) with intact atrioventricular conduction (PR interval 194±34, range 128-300 ms), left bundle branch block, and optimized LV lead position were studied at implant. QRS duration (QRSd) reduction was compared for the following pacing configurations: nominal simultaneous BiV (Mode I: paced/sensed atrioventricular delay=140/110 ms), BiV+SyncAV with 50 ms offset (Mode II), BiV+SyncAV with offset that minimized QRSd (Mode III), or LV-only pacing+SyncAV with 50 ms offset (Mode IV). The intrinsic QRSd (162±16 ms) was reduced to 142±17 ms (-11.8%) by Mode I, 136±14 ms (-15.6%) by Mode IV, and 132±13 ms (-17.8%) by Mode II. Mode III yielded the shortest overall QRSd (123±12 ms, -23.9% [P<0.001 versus all modes]) and was the only configuration without QRSd prolongation in any patient. QRS narrowing occurred regardless of QRSd, PR, or LV-paced intervals, or underlying ischemic disease.

Conclusions: Post-implant electrical optimization in already well-selected patients with left bundle branch block and optimized LV lead position is facilitated by patient-tailored BiV pacing adjusted to intrinsic atrioventricular timing using an automatic device-based algorithm.

Keywords: cardiac resynchronization therapy; left bundle branch block; optimization.

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Figures

Figure 1
Figure 1
Representative 12‐lead ECG for all pacing Modes. Simultaneous recordings of ECG leads in a single patient (A) displayed separately, for each Mode (left to right), and (B) depicted as a composite, for each pacing Mode (top to bottom). AVD indicates atrioventricular delay; BiV, biventricular pacing; QRSd, QRS duration.
Figure 2
Figure 2
Distribution of QRS duration (QRSd) according to device programming. Individual comparisons: (A) Intrinsic QRS vs biventricular pacing (BiV) (Mode I). B, Intrinsic QRS vs BiV+SyncAV (50 ms) (Mode II). C, Intrinsic QRS vs BiV+SyncAV (optimal) (Mode III). D, Intrinsic QRS vs LV only+SyncAV (50 ms) (Mode IV). Summary results: (E) QRS duration for intrinsic conduction and all 4 pacing Modes. F, Reduction in QRSd for all 4 pacing Modes, relative to intrinsic. Mode I: BiV; Mode II: BiV+SyncAV (50 ms); Mode III: BiV+SyncAV (optimal); Mode IV: left ventricular (LV) only+SyncAV (50 ms). Asterisk indicates P<0.05.
Figure 3
Figure 3
Left ventricular (LV)–only fusion pacing (Mode IV) reduced QRS duration (QRSd) by 15.6% relative to intrinsic, but individualized biventricular pacing (BiV) fusion pacing (Mode III) produced a greater effect (23.9% reduction, P<0.001 vs LV fusion pacing). *P<0.001.
Figure 4
Figure 4
A, Distribution of pacing Modes associated with the narrowest QRS duration (QRSd). Note: Total percentage exceeds 100% because the narrowest QRSd can be achieved by multiple pacing Modes. B, Distribution in directional QRSd change among patients, relative to intrinsic conduction (narrower in blue, wider in red).
Figure 5
Figure 5
Distribution of optimal SyncAV offsets associated with Mode III.
Figure 6
Figure 6
Scatter plots demonstrating the lack of correlation between the reduction in QRS duration (QRSd) and (A) QRS onset to right ventricular (RV) lead activation (qRV), (B) QRS onset to left ventricular (LV) lead activation (qLV), (C) LV‐paced to RV‐sensed time (LVpRVs), and (D) the lack of correlation between qLV and LVpRVs.
See this image and copyright information in PMC

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