Sympathetic toggled paroxysmal atrial fibrillation and recurrent premature atrial contractions in ambulatory patients

Background Autonomic nerve activity is important in the mechanisms of paroxysmal atrial fibrillation (PAF). Objective To test the hypothesis that a single burst of skin sympathetic nerve activity (SKNA) can toggle on and off PAF or premature atrial contraction (PAC) clusters. Methods We performed neuECG recording over 7 days in patients with PAF. Results In Study 1, we found 8 patients (7 men, 1 woman, 62±8 years) had 124 episodes of PAF. An SKNA burst toggled both on and off PAF in 8 (6.5%) episodes (Type 1), toggled on but not off in 12 (9.7%) episodes (Type 2), and toggled on a PAC cluster, followed by PAF in 4 (3.2%) episodes (Type 3). The duration of these PAF episodes was < 10 min. The remaining 100 (80.6%) episodes were associated with active SKNA bursts throughout PAF (Type 4) and lasted longer than Type 1 (p=0.0185) and Type 2 (p=0.0027) PAF. There were 47 PAC clusters. Among them, 24 (51.1%) were toggled on and off, and 23 (48.9%) were toggled on but not off by an SKNA burst. In Study 2, we found 17 patients (9 men, 8 women, 58±12 years) with < 10 min PAF (4, 8, 0, and 31 of Types 1-4, respectively). There were significant circadian variations of all types of PAF. Conclusions A single SKNA burst can toggle short-duration PAF and PAC cluster episodes on and off. The absence of continued SKNA after the onset might have affected the maintenance of these arrhythmias.