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Beta-blocker treatment of patients with atrial fibrillation attenuates abnormal electrical activity induced by spontaneous calcium release

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Aims: Atrial fibrillation (AF) has been associated with excessive spontaneous calcium release, linked to cyclic AMP (cAMP)-dependent phosphorylation of calcium regulatory proteins. Because β-blockers are expected to attenuate cAMP-dependent signaling, we aimed to examine whether the treatment of patients with β-blockers affected the incidence of spontaneous calcium release events or transient inward currents (ITI). Methods: The impact of treatment with commonly used β-blockers was analyzed in human atrial myocytes from 371 patients using patch-clamp technique, confocal calcium imaging or immunofluorescent labeling. Data were analyzed using multivariate regression analysis taking into account potentially confounding effects of relevant clinical factors RESULTS: The L-type calcium current (ICa) density was diminished significantly in patients with chronic but not paroxysmal AF and the treatment of patients with β-blockers did not affect ICa density in any group. By contrast, the ITI frequency was elevated in patients with either paroxysmal or chronic AF that did not receive treatment, and β-blocker treatment reduced the frequency to levels observed in patients without AF. Confocal calcium imaging showed that β-blocker treatment also reduced the calcium spark frequency in patients with AF to levels observed in those without AF. Furthermore, phosphorylation of the ryanodine receptor (RyR2) at Ser-2808 and phospholamban at Ser-16 was significantly lower in patients with AF that received β-blockers. Conclusion: Together, our findings demonstrate that β-blocker treatment may be of therapeutic utility to prevent spontaneous calcium release-induced atrial electrical activity; especially in patients with a history of paroxysmal AF displaying preserved ICa density.

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Biomedicine & Pharmacotherapy, 2023, vol. 158

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cc by-nc-nd (c) Jiménez Sábado, Verónica et al., 2023

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Articles publicats en revistes (Patologia i Terapèutica Experimental)

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Beta-blocker treatment of patients with atrial fibrillation attenuates abnormal electrical activity induced by spontaneous calcium release