ABSTRACT
BACKGROUND: It remains unclear what causes symptoms in patients with paroxysmal atrial fibrillation (AF). OBJECTIVE: This study aimed to correlate the magnitudes of the skin sympathetic nerve activity (SKNA) with symptoms in patients with AF. METHODS: We prospectively enrolled patients with symptomatic paroxysmal AF for ambulatory electrocardiogram and SKNA recording. Heart rhythms at time of symptoms were categorized as AF or normal sinus rhythm (NSR). Maximal and average SKNA (aSKNA) and heart rate (HR) were compared between symptomatic and asymptomatic AF and NSR episodes using mixed effects models to account for within-patient correlations. RESULTS: Among the 31 enrolled patients, 16 (52%) had at least one episode of AF, and 24 (77%) endorsed symptoms during the monitoring period. Compared with asymptomatic AF episodes, symptomatic AF episodes had higher maximal aSKNA (1.260 [IQR 1.114-1.723] µV vs. 1.108 [IQR 0.974-1.312] µV, p<0.001) and higher maximal HR (152±24 bpm vs. 132±19 bpm, p<0.001). Symptomatic NSR episodes were associated with higher maximal aSKNA (1.612 [IQR 1.287-2.027] µV vs. 1.332 [IQR 1.033-1.668] µV, p=0.001) and higher maximal HR (152±24 bpm vs. 105±16 bpm, p<0.001) than asymptomatic NSR episodes. Of the symptomatic episodes, 66 (73%) occurred during NSR and 24 (27%) during AF. All p-values were obtained from mixed effects models. CONCLUSION: Symptomatic episodes in patients with paroxysmal AF were more frequently associated with NSR than AF. Symptomatic AF and NSR episodes were associated with higher aSKNA than asymptomatic episodes. In patients with paroxysmal AF, symptoms correlate better with SKNA than heart rhythm.
