Skin sympathetic nerve activity and ventricular arrhythmias in acute coronary syndrome

Background

Acute coronary syndrome (ACS) is major cause of ventricular arrhythmias (VAs) and sudden death. neuECG is a noninvasive method to simultaneously record skin sympathetic nerve activity (SKNA) and electrocardiogram.

Objective

The purpose of this study was to test the hypotheses that (1) ACS increases average SKNA (aSKNA), (2) the magnitude of aSKNA elevation is associated with VAs during ACS, and (3) there is a gender difference in aSKNA between patients without and with ACS.

Methods

We prospectively studied 128 ACS and 165 control participants. The neuECG was recorded with electrodes at Lead I configuration at baseline, during mental math stress, and during recovery (5 minutes for each phase). All recordings were done in the morning.

Results

In the control group, women have higher aSKNA than do men at baseline (0.82 ± 0.25 μV vs 0.73 ± 0.20 μV; P = .009) but not during mental stress (1.21 ± 0.36 μV vs 1.16 ± 0.36 μV; P = .394), suggesting women had lower sympathetic reserve. In comparison, ACS is associated with equally elevated aSKNA in women vs men at baseline (1.14 ± 0.33 μV vs 1.04 ± 0.35 μV; P = .531), during mental stress (1.46 ± 0.32 μV vs 1.33 ± 0.37 μV; P = .113), and during recovery (1.30 ± 0.33 μV vs 1.11 ± 0.30 μV; P = .075). After adjusting for age and gender, the adjusted odds ratio for VAs including ventricular tachycardia and ventricular fibrillation is 1.23 (95% confidence interval 1.05–1.44) for each 0.1 μV aSKNA elevation. aSKNA is positively correlated with plasma norepinephrine level.

Conclusion

ACS is associated with elevated aSKNA, and the magnitude of aSKNA elevation is associated with the occurrence of VAs. Women have higher aSKNA and lower SKNA reserve than do men among controls but not among patients with ACS.