What is the risk of aortic valve replacement in patients with cardiac dysrhythmia, including atrioventricular (AV) nodal block?

From the Guidelines

Aortic valve replacement in patients with cardiac dysthymia, including AV nodal block, carries a significant risk of requiring permanent pacemaker implantation, with a frequency ranging between 3% and 8.5%. This risk is higher in patients with preoperative conduction disturbances, as noted in the 2018 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay 1. The primary risk is worsening of pre-existing conduction abnormalities, with up to 20-40% of patients developing new or worsened AV block requiring permanent pacemaker implantation post-surgery.

Key Risks and Considerations

• The need for pacemaker placement is frequent after aortic valve replacement, with a lower threshold for recommending pacing compared to mitral valve surgery, as the aortic valve is anatomically located near the bundle of His 1.
• Patients who have new atrioventricular block which does not resolve or sinoatrial node dysfunction should undergo pacemaker implantation before discharge for persistent symptomatic or hemodynamically significant bradycardia.
• Surgical trauma to the conduction system during valve debridement or suture placement can directly damage the AV node or His bundle.
• Management typically involves preoperative optimization of rhythm control, careful surgical technique to minimize trauma to conduction pathways, continuous cardiac monitoring post-procedure, and readiness for temporary or permanent pacing if needed.

Recommendations for Practice

• Patients should be informed that they may require permanent pacemaker implantation following AVR, particularly if they already have conduction abnormalities.
• The timing of pacemaker implantation should be individualized, but 3 to 5 days after surgery is probably reasonable, as suggested by the 2018 ACC/AHA/HRS guideline 1.
• The use of ambulatory electrocardiographic monitoring for the detection of high-degree atrio-ventricular block in patients with new-onset persistent left bundle branch block after transcatheter aortic valve implantation may be beneficial in identifying patients at risk for delayed high-degree AV block, as noted in the 2020 ACC expert consensus decision pathway on management of conduction disturbances in patients undergoing transcatheter aortic valve replacement 1.

From the Research

Risk of Aortic Valve Replacement with Cardiac Dysthymia including AV Nodal Block

• The risk of aortic valve replacement with cardiac dysthymia including AV nodal block is a significant concern in cardiac surgery 2, 3.
• Studies have shown that temporary atrioventricular (AV) conduction disturbances are a common complication following cardiac surgery, especially involving the aortic valve 2.
• The prevalence of permanent complete AV block has been estimated at 3-6% of all patients undergoing aortic valve replacement 2.
• Factors that affect the occurrence of complete AV block requiring permanent pacemaker implantation include prolonged cardiopulmonary bypass time, prolonged aortic cross-clamp time, larger size of the implanted valve prosthesis, endocarditis as the indication for surgery, and electrolyte disturbances 2.
• Iatrogenic AV block can occur in the context of cardiac surgery, percutaneous transcatheter, or electrophysiologic procedures, with patients undergoing aortic and/or mitral valve surgery being at the highest risk for developing perioperative AV block requiring permanent pacemaker implantation 3.
• The risk of delayed AV block in patients without procedural conduction disturbances during transcatheter aortic valve replacement is also a concern, with factors such as pre-existing abnormal ECG and low left ventricular ejection fraction (LVEF) increasing the risk 4.
• Baseline right bundle branch block (RBBB) has been associated with higher rates of permanent pacemaker implantation and death in patients undergoing transcatheter aortic valve replacement 5.

Predictors of AV Block

• Prolonged cardiopulmonary bypass time and prolonged aortic cross-clamp time have been identified as predictors of AV block 2, 6.
• Electrolyte disturbances and endocarditis as the indication for surgery have also been associated with an increased risk of AV block 2.
• Pre-existing abnormal ECG, such as first-degree AV block or abnormal QRS, increases the risk of delayed AV block 4.
• Low LVEF (< 50%) has also been identified as a predictor of delayed AV block 4.

Management Considerations

• Patients with pre-existing RBBB and without permanent pacemakers at discharge from the index hospitalization may be at especially high risk for high-degree atrioventricular block and/or sudden cardiac death during follow-up 5.
• A tailored strategy, with a minimalist approach (same or next-day discharge) in low-risk patients, and a more prolonged hospitalization or continuous ECG ambulatory monitoring in those at higher risk, may be necessary to manage the risk of delayed AV block 4.