Abstract Body (Do not enter title and authors here): Introduction. Atrial fibrillation (AF) is the most common arrhythmia and is a major risk factor for stroke. Existing therapies including ablation remain suboptimal. An increase in autonomic nerve signaling – both parasympathetic and sympathetic – is thought to contribute to AF genesis and progression. Therapies targeting atrial autonomic signaling may therefore attenuate arrhythmogenic substrate for AF.
Hypothesis. Combined gene therapy targeting parasympathetic (Gαi and Gαo), and sympathetic (Gαs) signaling will attenuate autonomic effects on atrial electrophysiology (EP), delaying AF onset and progression.
Methods. A polycistronic plasmid encoding inhibitory peptides for Gαi, Gαo, and Gαs (separated by P2A sequences) was injected in the canine (n=3) atria followed by electroporation to facilitate gene delivery. Controls included scrambled-sequence-injected and uninjected animals (n=10). Persistent AF (PersAF) was induced by rapid atrial pacing (RAP) over 12 weeks. Residual AF was evaluated at terminal EP study (Panel A).
Results. Controls developed persAF (100% AF burden) after 3.6±1.4 weeks of RAP. Combined (Gαi+Gαo+Gαs) gene therapy attenuated AF development – two animals developed persAF at 8±3 weeks, one animal never reached 100% AF burden and was mainly in atrial flutter until the terminal. The last day of sinus rhythm was extended (54±27 vs 22±13 days, treatment vs control). AF burden was significantly reduced by 35±20% at all timepoints (Panel B, p<0.05). AF at the terminal experiment displayed lower frequency and less fractionation in gene therapy animals (panel C), with one animal spontaneously converting to sinus rhythm.
Conclusion. Gene-based inhibition of parasympathetic and sympathetic signaling in the atria by expression of Gαi, Gαo, and Gαs inhibitory peptides successfully delays onset of AF and attenuates AF burden. These data emphasize an important mechanistic role for autonomic nerve activity in genesis and progression of AF. Future optimization of this multi-target gene therapy approach may offer promising novel treatments for AF.