Characterization of skin sympathetic nerve activity in patients with cardiomyopathy and ventricular arrhythmia

BACKGROUND Heightened sympathetic nerve activity is associated with occurrence of ventricular arrhythmia (VA). OBJECTIVE To investigate the association of skin sympathetic nerve activity (SKNA) and VA occurrence. METHODS We prospectively enrolled 65 patients with severe cardiomyopathy. Of these, 39 had recent sustained VA episodes (VA-1 group), 11 had intractable VA undergoing sedation with general anesthesia (VA-2 group), and 15 had no known history of VA (VA-Ctrl group). All patients had simultaneous SKNA and electrocardiogram recording. SKNA was assessed using an average value (aSKNA), a variable value (vSKNA), and the number of bursts of SKNA (bSKNA). RESULTS The VA-1 group had higher aSKNA and vSKNA compared with the VA-Ctrl group (aSKNA: 1.41 +/- 0.53 mu V vs 0.98 +/- 0.41 mu V, P = .003; vSKNA: 0.52 +/- 0.22 mu V vs 0.30 +/- 0.16 mu V, P < .001) and the VA-2 group (aSKNA: 0.83 +/- 0.22 mu V, P < .001; vSKNA: 0.23 +/- 0.11 mu V; P < .001). Although the VA- group had more VA episodes than the VA-1 group (median, 5 vs 2; P = .01), their SKNA was the lowest among the 3 groups. Multivariate Cox regression analysis showed that a higher aSKNA at baseline was an independent predictor of lower VA recurrence rate during a 417 +/- 279-day follow-up (hazard ratio, 0.325; 95% confidence interval [CI], 0.119-0.883; P = .03). A >15% reduction in aSKNA after therapy was associated with a lower subsequent VA event rate (hazard ratio, 0.222; 95% CI, 0.057-0.864; P = .03). CONCLUSION Patients with VA had increased SKNA as compared with control. Both SKNA and sustained VA could be suppressed by general anesthesia. The aSKNA at baseline was an independent predictor of VA recurrence.