Key result
Multifuse pacing linked to a ~38 ms reduction in QRS duration during CRT.
Why the study?
While adaptive AV-shortening algorithms and MPP narrow QRSd, incorporating these strategies together with intrinsic septal activation had not been explored.
Does a multifuse pacing technique combining multipoint pacing and AV-delay shortening reduce QRS duration in CRT patients?
Observational (n=22)
No
Does a multifuse pacing technique combining multipoint pacing and AV-delay shortening reduce QRS duration in CRT patients?
Effect estimate: Mean reduction 37.99 ms
Absolute Event Rate: 115.31% vs 153.31%
p-value: p=<0.0001
Multifuse pacing combining multipoint pacing and an AV-delay shortening algorithm significantly reduced QRS duration in CRT patients, with greater benefit seen in those with strictly defined LBBB.
Multifuse pacing may narrow QRS in CRT; hypothesis-generating and should not yet change practice.
Adaptive atrioventricular (AV)-shortening algorithms have achieved QRS duration (QRSd) narrowing in traditional cardiac resynchronization therapy (CRT) patients. Multipoint pacing (MPP) has also demonstrated benefit in this population. An additional site of activation via intrinsic conduction of the septum may further contribute to CRT; however, the incorporation of all strategies together has yet to be explored. We therefore developed and tested a method combining MPP-CRT and controlled septal contribution to create a multifuse pacing (MFP) technique, establishing four ventricular activation sites for CRT patients using measurements from intracardiac electrograms (EGMs) and incorporating an AV-delay shortening algorithm (SyncAV™; Abbott Laboratories, Chicago, IL, USA) to narrow the QRSd. Patients in sinus rhythm with an AV conduction time of less than 350 ms were included in this analysis and were further stratified by strictly defined left bundle branch block (sLBBB) or nonspecific intraventricular conduction delay (IVCD). EGM-based measurements to determine the QRS septal onset to right ventricular (RV) time (SRAT) and the left ventricular (LV) to RV pacing conduction time were collected and applied to a formula to facilitate MFP. QRSd was compared between before and after programming. A total of 22 patients (19 men and three women) with similar baseline characteristics were compared (all values in mean ± standard deviation). The overall baseline QRSd of 153.31 ± 24.60 ms was decreased to 115.31 ± 16.31 ms after MFP programming (p < 0.0001). The measured SRAT was 59.40 ± 28.49 ms, resulting in a negative AV offset of -20.0 ± 24.97 ms. Patients in the sLBBB group (n = 7) were aged 67.8 ± 13.3 years and had a QRSd of 168.85 ± 27.29 ms that decreased to 113 ± 16.69 ms for a reduction of 55.42 ± 19.3 ms or 32.1% (p = 0.0003). In the IVCD group (n = 15), the baseline QRSd of 146.06 ± 20.29 ms was decreased to 116 ± 16.66 ms for a reduction of 30.07 ± 16.41 ms or 20.62% (p = 0.0001). When comparing the sLBBB and IVCD groups, the sLBBB group was favored by a reduction of 25.35 ms (p = 0.00046). Ultimately, MFP achieved statistically significant reductions in QRSd in all patients tested in this analysis. The benefit was also significantly better in the sLBBB group as compared with in the IVCD group.
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Corbisiero et al. (2021) conducted an observational in Heart failure with indication for cardiac resynchronization therapy (n=22). Multifuse pacing (MFP) vs. Baseline was evaluated on QRS duration (Mean reduction 37.99 ms, p=<0.0001). Multifuse pacing significantly reduced QRS duration by 37.99 ms (from 153.31 ms to 115.31 ms) compared to baseline in patients receiving cardiac resynchronization therapy.
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