Shoemaker MB, Yoneda ZT, Crawford DM, Akers WS, Richardson T, Montgomery JA, Phillips S, Shyr Y, Saavedra P, Estrada J, Kanagasundram A, Shen ST, Michaud G, Crossley G, Ellis CR, Knollmann BC. A Mechanistic Clinical Trial Using (
R)- Versus
(S)-Propafenone to Test RyR2 (Ryanodine Receptor) Inhibition for the Prevention of Atrial Fibrillation Induction.
Circ Arrhythm Electrophysiol 2022;
15:e010713. [PMID:
36166682 PMCID:
PMC9588733 DOI:
10.1161/circep.121.010713]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Accepted: 08/16/2022] [Indexed: 11/16/2022]
Abstract
BACKGROUND
Experimental data suggest ryanodine receptor-mediated intracellular calcium leak is a mechanism for atrial fibrillation (AF), but evidence in humans is still needed. Propafenone is composed of two enantiomers that are equally potent sodium-channel blockers; however, (R)-propafenone is an ryanodine receptor inhibitor whereas (S)-propafenone is not. This study tested the hypothesis that ryanodine receptor inhibition with (R)-propafenone prevents induction of AF compared to (S)-propafenone or placebo in patients referred for AF ablation.
METHODS
Participants were randomized 4:4:1 to a one-time intravenous dose of (R)-propafenone, (S)-propafenone, or placebo. The study drug was given at the start of the procedure and an AF induction protocol using rapid atrial pacing was performed before ablation. The primary endpoint was 30 s of AF or atrial flutter.
RESULTS
A total of 193 participants were enrolled and 165 (85%) completed the study protocol (median age: 63 years, 58% male, 95% paroxysmal AF). Sustained AF and/or atrial flutter was induced in 60 participants (84.5%) receiving (R)-propafenone, 60 (80.0%) receiving (S)-propafenone group, and 12 (63.2%) receiving placebo. Atrial flutter occurred significantly more often in the (R)-propafenone (N=23, 32.4%) and (S)-propafenone (N=26, 34.7%) groups compared to placebo (N=1, 5.3%, P=0.029). There was no significant difference between (R)-propafenone and (S)-propafenone for the primary outcome of AF and/or atrial flutter induction in univariable (P=0.522) or multivariable analysis (P=0.199, adjusted for age and serum drug level).
CONCLUSIONS
There is no difference in AF inducibility between (R)-propafenone and (S)-propafenone at clinically relevant concentrations. These results are confounded by a high rate of inducible atrial flutter due to sodium-channel blockade.
REGISTRATION
https://clinicaltrials.gov; Unique Identifier: NCT02710669.
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