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Published on: November 11, 2022
Potassium Channel Blockade Enhances Atrial Fibrillation-Selective Antiarrhythmic Effects of Optimized State-Dependent
Martin Aguilar1, Feng Xiong1, Xiao Yan Qi1
1From the Research Center, Montreal Heart Institute and Université de Montréal, Montreal, QC, Canada (M.A., F.X., X.Y.Q., P.C., S.N.); Department of Molecular and Integrative Physiology/Institute of Biomedical Engineering (M.A., P.C.) and Department of Medicine (S.N.), Université de Montréal, Montreal, QC, Canada; and Departments of Medicine (M.A., S.N.) and Pharmacology and Therapeutics (F.X., S.N.), McGill University, Montreal, QC, Canada; and West-German Heart and Vascular Center, Faculty of Medicine, University Duisburg-Essen, Essen, Germany (S.N.).
Adding potassium (K(+)) channel blockers to sodium (Na(+)) channel blockers enhances atrial fibrillation (AF) rhythm control. This combination therapy shows improved atrial selectivity and efficacy in terminating AF, offering a promising antiarrhythmic drug strategy.
Area of Science:
- Cardiovascular Electrophysiology
- Pharmacology
- Computational Biology
Background:
- Developing effective and safe antiarrhythmic drugs for atrial fibrillation (AF) rhythm control remains a significant clinical challenge.
- Multichannel blockers are theoretically advantageous for AF over single-channel blockers, but their development has been empirical.
- This study investigated whether adding potassium (K(+))-channel blockade to optimized sodium (Na(+))-channel blockers improves atrial selectivity and anti-AF effects.
Purpose of the Study:
- To test the hypothesis that combined K(+)-channel and Na(+)-channel blockade enhances atrial selectivity and antiarrhythmic efficacy for AF.
- To evaluate the effects of combining optimized Na(+)-channel blockers with rapid (IKr) or ultrarapid (IKur) delayed-rectifier K(+)-channel blockade.
Main Methods:
- Utilized mathematical models of cardiomyocytes, tissue, and state-dependent Na(+)-channel block.
- Employed optical mapping and action potential recordings in realistic electrophysiological simulations.
- Conducted experiments in coronary-perfused canine hearts using pilsicainide (Na(+)-channel blocker) and dofetilide (IKr blocker).
Main Results:
- Mathematical models showed that combining an inactivated-state Na(+)-channel blocker with IKr block increased AF selectivity and AF termination efficacy.
- The combination therapy resulted in enhanced, rate-dependent, and atrium-selective INa reduction compared to Na(+)-channel blockade alone.
- In canine hearts, pilsicainide plus dofetilide demonstrated superior AF termination efficacy and rendered AF noninducible, unlike pilsicainide alone.
Conclusions:
- Potentiating K(+)-channel blockade alongside optimized Na(+)-channel blockade significantly enhances AF-selective antiarrhythmic effects.
- Combining optimized Na(+)-channel blockade with atrial K(+)-channel blockade represents a potentially valuable strategy for developing AF-selective antiarrhythmic drugs.
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