This prospective observational cohort study evaluated the effect of cardiac autonomic neuropathy (CAN) on perioperative ventricular repolarization, specifically QT and corrected QT (QTc) intervals, in patients undergoing elective coronary artery bypass grafting (CABG) surgery under general anesthesia. The study was conducted in a tertiary care university hospital between October 2023 and December 2024.

Adult patients scheduled for isolated elective CABG surgery with sinus rhythm on preoperative electrocardiography were screened for eligibility. Cardiac autonomic function was assessed preoperatively using standardized Ewing's cardiovascular reflex tests. Patients were classified into two groups according to test results: CAN-positive (≥2 abnormal tests) and CAN-negative (<2 abnormal tests).

QT and QTc intervals were measured at predefined perioperative time points, including before anesthesia induction, baseline, before intubation, at 1 and 30 minutes after intubation, before cannulation, and 24 hours postoperatively. The primary objective was to compare perioperative QT and QTc interval changes between patients with and without CAN. Secondary outcomes included QT and QTc variability (ΔQT, ΔQTc) and the incidence of clinically significant QTc prolongation.

This prospective observational study was designed to evaluate the impact of cardiac autonomic neuropathy (CAN) on perioperative ventricular repolarization parameters, specifically QT and corrected QT (QTc) intervals, in patients undergoing elective coronary artery bypass grafting (CABG) surgery under general anesthesia. The study was conducted at a tertiary care university hospital within the Departments of Anesthesiology and Cardiovascular Surgery between October 2023 and December 2024.

Patients scheduled for elective isolated CABG surgery with sinus rhythm on preoperative electrocardiography were screened for eligibility. Cardiac autonomic function was assessed preoperatively using standardized Ewing's cardiovascular reflex tests. Based on test results, patients were classified into two groups: CAN-positive (≥2 abnormal tests) and CAN-negative (<2 abnormal tests).

QT and QTc intervals were measured at predefined perioperative time points, and variability of repolarization parameters was also assessed. The primary aim was to compare perioperative QT and QTc interval changes between patients with and without CAN.

Inclusion Criteria:

• Age ≥18 years.
• Scheduled for elective isolated coronary artery bypass grafting (CABG).
• Sinus rhythm on preoperative 12-lead electrocardiography.
• Ability to undergo preoperative cardiovascular autonomic function assessment using Ewing's cardiovascular reflex tests.
• Written informed consent provided.

Exclusion Criteria:

• Previous cardiac surgery.
• Emergency CABG.
• Permanent pacemaker implantation.
• Atrial fibrillation or other clinically significant cardiac arrhythmias.
• Bundle branch block.
• Congenital long QT syndrome.

Adult patients scheduled for elective isolated coronary artery bypass grafting (CABG) surgery under general anesthesia at a tertiary care university hospital.