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 Oct;15(10):e010713. doi: 10.1161/CIRCEP.121.010713. Epub 2022 Sep 27.


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.

Keywords: ablation; atrial fibrillation; calcium leak; clinical trial; propafenone.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Anti-Arrhythmia Agents / therapeutic use
  • Atrial Fibrillation* / diagnosis
  • Atrial Fibrillation* / drug therapy
  • Atrial Fibrillation* / prevention & control
  • Atrial Flutter* / diagnosis
  • Atrial Flutter* / prevention & control
  • Calcium / metabolism
  • Female
  • Humans
  • Male
  • Middle Aged
  • Propafenone / adverse effects
  • Ryanodine Receptor Calcium Release Channel
  • Sodium


  • Propafenone
  • Ryanodine Receptor Calcium Release Channel
  • Calcium
  • Sodium
  • Anti-Arrhythmia Agents

Associated data

  • ClinicalTrials.gov/NCT02710669