Carotid artery stenting and endarterectomy have different effects on heart rate variability

Due to their close proximity to the carotid sinus baroreceptor region, carotid endarterectomy (CEA) and carotid angioplasty/stenting (CAS) carry an inherent risk of affecting baroreflex-mediated regulation of the heart rate. Variations in the heart rate can be studied by measuring heart rate variability (HRV), in which distinct frequency bands in the power spectrum represent sympathetic and parasympathetic modulations on sinus node pacemaker activity. We aimed to investigate the influence of CEA and CAS on HRV.

One-hour recordings of R-R intervals on ECG were obtained before and after CEA (10 patients) or CAS (12 patients). The power spectrum of the R-R time series was estimated using the FFT technique. The power in low frequency (LF) and high frequency (HF) bands were computed and normalized to their total power (TP). The LF/HF ratio, an index of sympathovagal balance, was calculated.

Compared to preoperative levels, LF/HF exhibited 85%, 96%, and 70% increase on the second, third, and fourth days after CEA, respectively. In contrast, LF/HF decreased by 26%, 32%, and 26% on the respective days following CAS; the difference between groups was significant (p=0.0069). Normalized LF increased after CEA and decreased after CAS, while the opposite was observed for normalized HF (p=0.0217). There was no significant change in TP.

CEA and CAS have differential effects on the sympathovagal balance on the heart. The relative increase in sympathetic modulation after CEA and parasympathetic modulation after CAS are likely mediated by alterations in the sensitivity of carotid sinus baroreceptors. Altered cardiac autonomic modulation may play a role in the occurrence of cardiac disturbances following carotid interventions.