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Left ventricular paced activation in cardiac resynchronization therapy patients with left bundle branch block and relationship to its electrical substrate

BACKGROUND: Cardiac resynchronization therapy (CRT) uses left ventricular (LV) pacing to restore rapid synchronized LV activation when it is delayed in patients with myocardial disease. OBJECTIVE: Although intrinsic LV activation delays are understood, little is known about reactions to LV stimulati...

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Autores principales: Wisnoskey, Brian J., Varma, Niraj
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Elsevier 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8183968/
https://www.ncbi.nlm.nih.gov/pubmed/34113862
http://dx.doi.org/10.1016/j.hroo.2020.04.002
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author Wisnoskey, Brian J.
Varma, Niraj
author_facet Wisnoskey, Brian J.
Varma, Niraj
author_sort Wisnoskey, Brian J.
collection PubMed
description BACKGROUND: Cardiac resynchronization therapy (CRT) uses left ventricular (LV) pacing to restore rapid synchronized LV activation when it is delayed in patients with myocardial disease. OBJECTIVE: Although intrinsic LV activation delays are understood, little is known about reactions to LV stimulation and whether they are affected by QRS duration (QRSd), morphology, LV substrate, or choice of electrode pair. The purpose of this study was to test these interactions. METHODS: In 120 heart failure patients with left bundle branch block (LBBB) and QRS >120 ms receiving CRT with quadripolar LV leads, device-based measurements of intrinsic activation delay (qLV) and paced inter- (and intra-) LV conduction times were evaluated at the proximal and distal LV bipoles. RESULTS: During intrinsic conduction, qLV varied little between the proximal and distal pairs in patients with LBBB (n = 120; age 68 ± 11 years; 63% male; ejection fraction 25% ± 7%; 33% ischemic cardiomyopathy; QRSd 162 ± 19 ms). A minority (30%) had conduction barriers (ie, gradients) (ΔqLV 29 ± 8 ms vs 9 ± 5 ms in patients without gradients; P <.01), which occurred equally in ischemic and nonischemic patients. A majority were functional (and not scar-mediated), as they resolved with pacing in most patients (75%). Importantly, LV-paced conduction times were unrelated to baseline QRS morphology (LBBB 166 ± 30 ms vs RBBB control 172 ± 30 ms; P = NS), longer than intrinsic conduction (166 ± 30 ms vs 129 ± 28 ms; P <.01), and varied significantly by electrode pair (ie, small distances) and etiology. Correlation between intrinsic activation delay (qLV) and LV-paced conduction time was poor (R(2) = 0.278; P <.05). CONCLUSION: LV-paced effect, which is core to CRT, is unpredictable based on conventionally used measures and should be considered during CRT optimization.
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spelling pubmed-81839682021-06-09 Left ventricular paced activation in cardiac resynchronization therapy patients with left bundle branch block and relationship to its electrical substrate Wisnoskey, Brian J. Varma, Niraj Heart Rhythm O2 Clinical BACKGROUND: Cardiac resynchronization therapy (CRT) uses left ventricular (LV) pacing to restore rapid synchronized LV activation when it is delayed in patients with myocardial disease. OBJECTIVE: Although intrinsic LV activation delays are understood, little is known about reactions to LV stimulation and whether they are affected by QRS duration (QRSd), morphology, LV substrate, or choice of electrode pair. The purpose of this study was to test these interactions. METHODS: In 120 heart failure patients with left bundle branch block (LBBB) and QRS >120 ms receiving CRT with quadripolar LV leads, device-based measurements of intrinsic activation delay (qLV) and paced inter- (and intra-) LV conduction times were evaluated at the proximal and distal LV bipoles. RESULTS: During intrinsic conduction, qLV varied little between the proximal and distal pairs in patients with LBBB (n = 120; age 68 ± 11 years; 63% male; ejection fraction 25% ± 7%; 33% ischemic cardiomyopathy; QRSd 162 ± 19 ms). A minority (30%) had conduction barriers (ie, gradients) (ΔqLV 29 ± 8 ms vs 9 ± 5 ms in patients without gradients; P <.01), which occurred equally in ischemic and nonischemic patients. A majority were functional (and not scar-mediated), as they resolved with pacing in most patients (75%). Importantly, LV-paced conduction times were unrelated to baseline QRS morphology (LBBB 166 ± 30 ms vs RBBB control 172 ± 30 ms; P = NS), longer than intrinsic conduction (166 ± 30 ms vs 129 ± 28 ms; P <.01), and varied significantly by electrode pair (ie, small distances) and etiology. Correlation between intrinsic activation delay (qLV) and LV-paced conduction time was poor (R(2) = 0.278; P <.05). CONCLUSION: LV-paced effect, which is core to CRT, is unpredictable based on conventionally used measures and should be considered during CRT optimization. Elsevier 2020-05-11 /pmc/articles/PMC8183968/ /pubmed/34113862 http://dx.doi.org/10.1016/j.hroo.2020.04.002 Text en © 2020 Heart Rhythm Society. Published by Elsevier Inc. https://creativecommons.org/licenses/by-nc-nd/4.0/This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
spellingShingle Clinical
Wisnoskey, Brian J.
Varma, Niraj
Left ventricular paced activation in cardiac resynchronization therapy patients with left bundle branch block and relationship to its electrical substrate
title Left ventricular paced activation in cardiac resynchronization therapy patients with left bundle branch block and relationship to its electrical substrate
title_full Left ventricular paced activation in cardiac resynchronization therapy patients with left bundle branch block and relationship to its electrical substrate
title_fullStr Left ventricular paced activation in cardiac resynchronization therapy patients with left bundle branch block and relationship to its electrical substrate
title_full_unstemmed Left ventricular paced activation in cardiac resynchronization therapy patients with left bundle branch block and relationship to its electrical substrate
title_short Left ventricular paced activation in cardiac resynchronization therapy patients with left bundle branch block and relationship to its electrical substrate
title_sort left ventricular paced activation in cardiac resynchronization therapy patients with left bundle branch block and relationship to its electrical substrate
topic Clinical
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8183968/
https://www.ncbi.nlm.nih.gov/pubmed/34113862
http://dx.doi.org/10.1016/j.hroo.2020.04.002
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