Skin sympathetic nerve activity and ventricular rate control during atrial fibrillation

BACKGROUND The relationship between the ventricular rate (VR) during atrial fibrillation (AF) and skin sympathetic nerve activity (SKNA) remains unclear. OBJECTIVE The purpose of this study was to test the hypothesis that SKNA bursts accelerate VR during AF. METHODS We simultaneously recorded electrocardiogram and SKNA in 8 patients (median age 66.0 years [interquartile range {IQR} 59.0-77.0 years]; 4 men [50%]) with 30 paroxysmal AF episodes (all >10-minute long) and 12 patients (73.0 years [IQR 60.5-80.0 years]; 6 men [50%]) with persistent AF. The average amplitude of SKNA (aSKNA [mu V]) during AF was analyzed in 1-minute windows and binned, showing 2 Gaussian distributions. We used the mean +3SD of the first Gaussian distribution as the threshold that separates burst from baseline (nonburst) SKNA. All 1-minute aSKNA values above the threshold were detected, and the area between aSKNA and baseline of every 1 minute was calculated and added as burst area. RESULTS VR was higher during SKNA bursts than during the nonburst period (103 beats/min [IQR 83-113 beats/min] vs 88 beats/min [IQR 76-101 beats/min], respectively; P=.003). In the highest quartile of the burst area during persistent AF, the scatterplot of maximal aSKNA and VR during each SKNA burst shows higher aSKNA and VR. The overall estimate of the correlation between maximal VR and aSKNA during bursts show a positive correlation in the highest quartile of the burst area (0.64; 95% confidence interval 0.54-0.74; P<.0001). CONCLUSION SKNA bursts are associated with VR acceleration. These SKNA bursts may be new therapeutic targets for rate control during AF.