Induced atrial fibrillation significantly increased sympathetic nerve activity compared with normal sinus rhythm (171% vs 100%; P<0.01), an effect partly attributable to irregular ventricular response.
Does induced atrial fibrillation and an irregular ventricular response increase sympathetic nerve activity in patients undergoing electrophysiological study?
Induced atrial fibrillation increases sympathetic nerve activity, partly due to the irregular ventricular response, suggesting potential benefits of restoring sinus rhythm or regularity, especially in heart failure.
Absolute Event Rate: 171% vs 100%
p-value: p=<0.01
BACKGROUND: Although the hemodynamic changes associated with atrial fibrillation (AF) have been extensively studied, the neural changes remain unclear. We hypothesized that AF is associated with an increase in sympathetic nerve activity (SNA) and that the irregular ventricular response contributes to this state of sympathoexcitation. METHODS AND RESULTS: In 8 patients referred for an electrophysiological study, SNA, blood pressure (BP), central venous pressure (CVP), and heart rate were recorded during 3 minutes of normal sinus rhythm (NSR) and 3 minutes of induced AF. In 5 of 8 patients who converted to NSR, right atrial (RA) pacing was performed for 3 minutes in atrial pacing triggered by ventricular sensing mode triggered by playback of an FM tape previously recorded from the right ventricle during AF (RA-irregular) and atrial pacing inhibited by atrial sensing mode at a rate equal to the mean heart rate obtained during AF (RA-regular). SNA data were expressed as percentage of baseline during NSR. SNA increased in all 8 patients during induced AF compared with NSR (171+/-40% versus 100%, respectively; P<0.01). This was associated with a trend for a decrease in BP and an increase in CVP (P=0.02). Similarly, SNA was significantly higher during RA-irregular pacing compared with RA-regular pacing (124+/-24% versus 91+/-20%, respectively; P=0.03). BP and CVP were not significantly different between the 2 pacing modes. CONCLUSIONS: Induced AF results in a significant increase in SNA, which is in part attributable to the irregular ventricular response. Our findings suggest that restoring NSR or regularity might be beneficial, particularly in patients with heart failure.
Wasmund et al. (Mon,) conducted a other in Referred for electrophysiological study (n=8). Induced atrial fibrillation and irregular right atrial pacing vs. Normal sinus rhythm and regular right atrial pacing was evaluated on Sympathetic nerve activity (SNA) as percentage of baseline (p=<0.01). Induced atrial fibrillation significantly increased sympathetic nerve activity compared with normal sinus rhythm (171% vs 100%; P<0.01), an effect partly attributable to irregular ventricular response.