Abnormal heart rate variability and atrial fibrillation after aortic surgery

Area of Science:

• Cardiovascular Surgery
• Cardiac Electrophysiology
• Autonomic Nervous System

Background:

• Complete cardiac denervation in heart transplantation is protective against postoperative atrial fibrillation.
• Surgical procedures involving transection of the ascending aorta can lead to varying degrees of autonomic denervation.

Purpose of the Study:

• To investigate whether the extent of cardiac denervation achieved through ascending aorta resection impacts the incidence of postoperative atrial fibrillation.
• To compare the incidence of postoperative atrial fibrillation in patients undergoing ascending aorta replacement versus aortic valve replacement.

Main Methods:

• Retrospective analysis of 67 patients undergoing ascending aorta graft replacement (Group A) and 132 patients undergoing aortic valve replacement (Group B).
• Evaluation of postoperative atrial fibrillation episodes within a 1-month follow-up period.
• Assessment of Heart Rate Variability (HRV) parameters from 24-h Holter recordings, alongside clinical, echocardiographic, and treatment data.

Main Results:

• Overall, 45% of patients experienced at least one episode of postoperative atrial fibrillation (43% in Group A, 46% in Group B).
• Older age was correlated with a higher incidence of postoperative atrial fibrillation.
• A subgroup of patients with aortic transection exhibiting signs of greater autonomic derangement (low HRV, high mean heart rate) showed a significantly lower incidence of postoperative atrial fibrillation (22% vs. 54%).

Conclusions:

• Transection of the ascending aorta during aortic aneurysm repair did not provide a significant protective effect against postoperative atrial fibrillation compared to an intact aorta.
• The observed limited and heterogeneous cardiac denervation may create an electrophysiological substrate contributing to the high incidence of postoperative atrial fibrillation.
• Further research is needed to understand the precise role of autonomic denervation in the context of aortic surgery and atrial fibrillation.