Abstract
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.
Highlights
Cardiac resynchronization therapy (CRT) is a wellestablished treatment for patients with symptomatic systolic heart failure (HF) and interventricular conduction abnormalities.[1,2,3,4] this therapy has shown great benefit in numerous clinical trials, nonresponse remains substantial, ranging from 25% to 30% depending on howThe Journal of Innovations in Cardiac Rhythm Management, January 2021response is defined.[5,6] In screening for CRT, concentration and attention to the QRS duration (QRSd) are critical to ensure that adequate prolongation exists in association with the New York Heart Association (NYHA) class to meet current guidelines.[7]
When the morphology in the strict definition of left bundle branch block includes left ventricular (LV) conduction delay evidenced by a QRSd of at least 140 ms in men or at least 130 ms in women
As all the techniques and algorithms in this analysis are approved by the United States Food and Drug Administration (FDA) and the programming is temporary in nature, our institutional review board waived the need for a formal protocol submission
Summary
Cardiac resynchronization therapy (CRT) is a wellestablished treatment for patients with symptomatic systolic heart failure (HF) and interventricular conduction abnormalities.[1,2,3,4] this therapy has shown great benefit in numerous clinical trials, nonresponse remains substantial, ranging from 25% to 30% depending on howThe Journal of Innovations in Cardiac Rhythm Management, January 2021response is defined.[5,6] In screening for CRT, concentration and attention to the QRS duration (QRSd) are critical to ensure that adequate prolongation exists in association with the New York Heart Association (NYHA) class to meet current guidelines.[7]. Cardiac resynchronization therapy (CRT) is a wellestablished treatment for patients with symptomatic systolic heart failure (HF) and interventricular conduction abnormalities.[1,2,3,4] this therapy has shown great benefit in numerous clinical trials, nonresponse remains substantial, ranging from 25% to 30% depending on how. The adoption of mid-QRS notching in at least two of the leads I, aVL, V1, V2, V5, and/or V6 has shown clear benefit when using the sLBBB criteria over incomplete or generalized intraventricular conduction delay (IVCD) when CRT therapy is initiated.[8,9,10]. Some studies have suggested that one-third of patients diagnosed with LBBB may not have complete LBBB but instead an incomplete bundle with some degree of LV enlargement; interestingly, this patient group is of a similar size to the CRT nonresponder population.[11,12,13,14] the addition of multiple sites of LV activation with CRT [multipoint pacing (MPP)] was not available at the time of most previous studies and may have led to different outcomes
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Journal of Innovations in Cardiac Rhythm Management
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
