Distinct impacts of heart rate and right atrial-pacing on left atrial mechanical activation and optimal AV delay in CRT

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Kyriacou, Andreas, Rajkumar, Christopher A, Pabari, Punam A, Sohaib, SM Afzal, Willson, Keith, Peters, Nicholas S, Lim, Phang B, Kanagaratnam, Prapa, Hughes, Alun D ORCID: 0000-0001-5432-5271, Mayet, Jamil et al (show 2 more authors) (2018) Distinct impacts of heart rate and right atrial-pacing on left atrial mechanical activation and optimal AV delay in CRT. Pacing and Clinical Electrophysiology, 41 (8). pp. 959-966.

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Official URL: http://dx.doi.org/10.1111/pace.13401

Abstract

<h4>Background</h4>Controversy exists regarding how atrial activation mode and heart rate affect optimal atrioventricular (AV) delay in cardiac resynchronization therapy. We studied these questions using high-reproducibility hemodynamic and echocardiographic measurements.<h4>Methods</h4>Twenty patients were hemodynamically optimized using noninvasive beat-to-beat blood pressure at rest (62 ± 11 beats/min), during exercise (80 ± 6 beats/min), and at three atrially paced rates: 5, 25, and 45 beats/min above rest, denoted as A<sub>paced,r+5</sub> , A<sub>paced,r+25</sub> , and A<sub>paced,r+45</sub> , respectively. Left atrial myocardial motion and transmitral flow were timed echocardiographically.<h4>Results</h4>During atrial sensing, raising heart rate shortened optimal AV delay by 25 ± 6 ms (P < 0.001). During atrial pacing, raising heart rate from A<sub>paced,r+5</sub> to A<sub>paced,r+25</sub> shortened it by 16 ± 6 ms; A<sub>paced,r+45</sub> shortened it 17 ± 6 ms further (P < 0.001). In comparison to atrial-sensed activation, atrial pacing lengthened optimal AV delay by 76 ± 6 ms (P < 0.0001) at rest, and at ∼20 beats/min faster, by 85 ± 7 ms (P < 0.0001), 9 ± 4 ms more (P = 0.017). Mechanically, atrial pacing delayed left atrial contraction by 63 ± 5 ms at rest and by 73 ± 5 ms (i.e., by 10 ± 5 ms more, P < 0.05) at ∼20 beats/min faster. Raising atrial rate by exercise advanced left atrial contraction by 7 ± 2 ms (P = 0.001). Raising it by atrial pacing did not (P = 0.2).<h4>Conclusions</h4>Hemodynamic optimal AV delay shortens with elevation of heart rate. It lengthens on switching from atrial-sensed to atrial-paced at the same rate, and echocardiography shows this sensed-paced difference in optima results from a sensed-paced difference in atrial electromechanical delay. The reason for the widening of the sensed-paced difference in AV optimum may be physiological stimuli (e.g., adrenergic drive) advancing left atrial contraction during exercise but not with fast atrial pacing.

Item Type:	Article
Uncontrolled Keywords:	atrioventricular delay, cardiac resynchronization therapy, electrophysiology-clinical, heart failure, optimization
Depositing User:	Symplectic Admin
Date Deposited:	12 Feb 2019 10:17
Last Modified:	13 Feb 2024 15:41
DOI:	10.1111/pace.13401
Open Access URL:	https://doi.org/10.1111/pace.13401
Related URLs:	Author Publisher
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3032705