Differential efficacy of L- and T-type calcium channel blockers in preventing tachycardia-induced atrial remodeling in dogs
Open Access
- 1 March 2001
- journal article
- Published by Oxford University Press (OUP) in Cardiovascular Research
- Vol. 49 (4) , 762-770
- https://doi.org/10.1016/s0008-6363(00)00288-1
Abstract
Background: Tachycardia-induced remodeling likely plays an important role in atrial fibrillation (AF) maintenance and recurrence after cardioversion, and Ca2+ overload may be an important mediator. This study was designed to evaluate the relative efficacies of selective T-type (mibefradil) and L-type (diltiazem) Ca2+-channel blockers in preventing tachycardia-induced atrial remodeling. Methods: Dogs were given daily doses of mibefradil (100 mg), diltiazem (240 mg) or placebo in a blinded fashion, beginning 4 days before and continuing through a 7-day period of atrial pacing at 400 bpm. An electrophysiological study was then performed to assess changes in refractoriness, refractoriness heterogeneity and AF duration. Results: Mean duration of burst-pacing induced AF was similar in placebo (567±203 s) and diltiazem-treated (963±280 s, P = NS) animals, but was much less in mibefradil-treated dogs (3.6±0.9 s, PConclusions: Whereas the selective T-type Ca2+-channel blocker mibefradil protects against atrial remodeling caused by 7-day atrial tachycardia, the selective L-type blocker diltiazem is without effect. These findings are potentially important for understanding the mechanisms and prevention of clinically-relevant atrial-tachycardia-induced remodeling.Keywords
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