Prolonged Autonomic Fluctuation Derived from Parasympathetic Hypertonia after Carotid Endarterectomy but not Stenting

Carotid endarterectomy (CEA) is a standard treatment for carotid artery stenosis, but the incidence after periprocedural myocardial infarction (MI) is not negligible. The mechanism for the higher risk of MI following CEA compared with the carotid artery stenting (CAS) is unclear. We hypothesized that it may be explained by different autonomic nervous responses.

This prospective, nonrandomized, observational study enrolled 50 patients from 2 centers: 25 underwent CEA and 25 CAS. Cardiac autonomic nervous activity was evaluated using 24-hour high-resolution ambulatory electrocardiography with parameters such as deceleration capacity (DC) and heart rate variability before the procedure, and at 1 week and 1-3 months after the procedure.

One week after CEA, decreased DC and increased acceleration capacity were recognized. Standard deviation of sequential 5-minute NN interval means and the low-frequency and high-frequency components were all decreased. By the later phase measurement, these changes returned to baseline or beyond. The results suggest that diminished autonomic activity reversed to excessive parasympathetic dominance. In contrast, the patients treated by CAS showed no remarkable autonomic modification in the early or later phases.

Distinct changes of sympathovagal response observed after CEA coincides with the time at which MI onset occurs, suggesting prolonged autonomic fluctuation may be a factor in the MI incidence after CEA.