Differential contributions of atrial tachycardia and ventricular response to AF-promoting refractoriness and conduction remodeling - 06/01/20
Résumé |
Background |
AF can cause atrial remodeling via fast atrial and/or ventricular rate; their relative role is unknown.
Purpose |
To analyze the specific roles of atrial tachycardia vs. high ventricular rate in AF on atrial remodeling.
Methods |
Four groups of 12dogs were followed for 3wks: 600bpm atrial tachypacing (ATP) maintaining AF (AF w/o AVB), ATP with AV node ablation (AF+AVB), 160bpm ventricular pacing (V160) reproducing the ventricular rate during AF, and sinus rhythm with AVB/V-pacing at 80bpm (CTL).
Results |
At terminal open-chest study, electrophysiological remodeling was observed (Fig. 1A) with left atrial (LA) reduced effective refractory period in AF w/o AVB and AF+AVB groups vs. V160 and CTL. AF induction vulnerability to single extrastimuli was increased in AF w/o AVB and AF+AVB vs. CTL, but was unchanged in V160. Burst pacing induced AF duration was significantly increased in AF w/o AVB (14±9min, P<0.05) but not in AF+AVB (6±9min) or V160 (2±5min) vs. CTL (5±4s). Conduction velocity was decreased in AF w/o AVB (74cm/s, P<0.05) vs. CTL (129cm/s), to a greater extent than in AF+AVB and V160 (91 and 92cm/s) (Fig. 1B). Collagen was upregulated in AF w/o AVB vs. CTL (P<0.01, Fig. 1C). Fibrosis assessed by Masson Trichrome was increased in AF w/o AVB (18±6%), AF+AVB (12±5%) and V160 (12±4%) vs. CTL (3±1%, P<0.05). SCN5A was decreased equally in AF w/o AVB, AF+AVB and V160 vs. CTL (Fig. 1D). Connexin43 mRNA and protein expression was reduced in AF w/o AVB vs. other groups (Fig. 1D).
Conclusions |
Both atrial tachycardia and ventricular response contribute to AF-promoting electrical and structural remodeling, with distinctive roles that need to be considered in preventive strategies.
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Vol 12 - N° 1
P. 144 - janvier 2020 Retour au numéroBienvenue sur EM-consulte, la référence des professionnels de santé.