Can Ablation for SVT and Atrial Fibrillation Cause Bradycardia?
Yes, catheter ablation for SVT and atrial fibrillation can cause bradycardia, though the risk varies significantly depending on the specific type of ablation performed and the anatomical target.
Risk by Ablation Type
AVNRT (Slow Pathway) Ablation
- AV block occurs in approximately 1% of cases when targeting the slow pathway along the posteroseptal tricuspid annulus 1.
- Complete heart block requiring permanent pacemaker implantation is the most serious bradycardic complication 1.
- The risk is substantially lower with slow-pathway ablation (1%) compared to fast-pathway ablation (8%) 1.
- Pre-existing first-degree AV block does not significantly increase the risk of complete heart block, though caution is warranted 1.
Atrial Fibrillation Ablation
- Bradycardia is not a common direct complication of standard pulmonary vein isolation or left atrial ablation 2, 3.
- Complication rates for AF ablation range from 6-10%, but these primarily involve vascular access issues, cardiac perforation, and thromboembolic events rather than bradycardia 2.
- Sinus node dysfunction may be unmasked after successful AF ablation in patients with underlying sick sinus syndrome or tachycardia-bradycardia syndrome 4, 5.
Atrial Flutter (CTI) Ablation
- Bradycardia is not a typical complication of cavotricuspid isthmus ablation 1.
- Success rates exceed 90% with an excellent safety profile 1.
- Post-ablation bradycardia, when it occurs, typically reflects underlying sinus node dysfunction that was masked by the tachyarrhythmia 6, 4.
AV Junction Ablation (Intentional Bradycardia)
- Complete AV block is the intended outcome when performing AV nodal ablation for rate control in refractory atrial arrhythmias 7.
- This procedure has 70-95% efficacy (typically ≥87%) and requires permanent pacemaker implantation 7.
- Complication rates are generally less than 2%, with procedure-related mortality at 0.1% 7.
- Late sudden death may occur following AV junction ablation, though this risk is lower with radiofrequency compared to DC shock ablation 7.
Inadvertent Bradycardia During Modification Procedures
- When attempting AV nodal modification (rather than complete ablation) to slow ventricular response without creating complete block, inadvertent complete AV block can occur 7.
- This represents the most common complication of AV node modification procedures—unintended ablation of both fast and slow pathways 7.
Clinical Context: Tachycardia-Bradycardia Syndrome
- In patients with underlying sick sinus syndrome presenting as tachycardia-bradycardia syndrome, successful ablation may unmask the bradycardic component 4, 5, 8.
- However, catheter ablation for TBS is superior to pacemaker therapy alone, with 70.9% of patients maintaining sinus rhythm without long pauses or need for antiarrhythmic drugs at 10-year follow-up 8.
- AF ablation in TBS patients reduces all-cause mortality, stroke, heart failure, and progression to persistent AF compared to pacemaker therapy 5.
Key Pitfalls to Avoid
- Do not assume post-ablation bradycardia is always a complication—it may represent unmasking of pre-existing sinus node dysfunction that was obscured by the tachyarrhythmia 4, 8.
- Monitor closely for bradycardia when using rate-control medications (beta-blockers, calcium channel blockers) after ablation, as these can exacerbate any underlying bradycardic tendency 6.
- Recognize that antiarrhythmic drugs (sotalol, amiodarone, dofetilide) used for rhythm control are associated with bradycardia as a side effect independent of the ablation procedure 1.
Bottom Line
For standard SVT ablations (AVNRT, accessory pathways) and AF ablations, clinically significant bradycardia requiring pacemaker implantation occurs in approximately 1% or less of cases. The primary exception is intentional AV junction ablation, which creates complete heart block by design and always requires permanent pacing.