RESUMO
BACKGROUND: The causes of symptoms in patients with paroxysmal atrial fibrillation (AF) remains unclear. OBJECTIVE: The purpose of this study was to correlate the magnitudes of skin sympathetic nerve activity (SKNA) with symptoms in patients with AF. METHODS: We prospectively enrolled patients with symptomatic paroxysmal AF for ambulatory electrocardiography and SKNA recording. Heart rhythms at the time of symptoms were categorized as AF or normal sinus rhythm (NSR). Maximal and average skin sympathetic nerve activity (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 1 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 [interquartile range (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 <.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 = .001) and higher maximal HR (152 ± 24 bpm vs 105 ± 16 bpm; P <.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.
RESUMO
BACKGROUND: Autonomic nerve activity is important in the mechanisms of paroxysmal atrial fibrillation (PAF). OBJECTIVE: The purpose of this study was 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: Simultaneous recording of SKNA and electrocardiogram (neuECG) recording was performed over 7 days in patients with PAF. RESULTS: In study 1, 8 patients (7 men and 1 woman; age 62 ± 8 years) had 124 episodes of PAF. An SKNA burst toggled both on and off PAF in 8 episodes (6.5%) (type 1), toggled on but not off in 12 episodes (9.7%) (type 2), and toggled on a PAC cluster followed by PAF in 4 episodes (3.2%) (type 3). The duration of these PAF episodes was <10 minutes. The remaining 100 episodes (80.6%) were associated with active SKNA bursts throughout PAF (type 4) and lasted longer than type 1 (P = .0185) and type 2 (P = .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, 17 patients (9 men and 8 women; age 58 ± 12 years) had <10 minutes of PAF (4, 8, 0, and 31 of types 1, 2, 3, and 4, respectively). There were significant circadian variations of all types of PAF. CONCLUSION: 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.
