How do cryotherapy and radiofrequency (RF) ablation compare to pulsed field ablation for treating atrioventricular nodal reentrant tachycardia (AVNRT)?

Comparison of Ablation Techniques for AVNRT

Radiofrequency ablation should be considered the first-line ablation technique for AVNRT due to its high success rate (>95%) and low recurrence rate (3.4%), while pulsed field ablation remains investigational with insufficient evidence to recommend its routine use over established techniques. 1

Current Standard of Care for AVNRT

Catheter ablation is the recommended first-line therapy for symptomatic AVNRT, with slow pathway ablation (modification) being the preferred approach. According to the 2016 ACC/AHA/HRS guidelines, catheter ablation:

• Is potentially curative with success rates >95%
• Eliminates the need for chronic pharmacological therapy
• Has a <1% risk of AV block when performed by experienced operators 1

Comparison of Ablation Techniques

Radiofrequency Ablation (RF)

• Efficacy: Highest long-term success rate (96.5% freedom from recurrence)
• Procedure time: Shorter total procedure time compared to cryoablation
• Risk: 0.87% risk of permanent AV block
• Evidence quality: Extensive long-term data with large patient populations 2

Cryoablation

• Efficacy: Slightly lower long-term success rate (90.9% freedom from recurrence)
• Safety advantage: Near-zero risk of permanent AV block (0% in meta-analysis)
• Procedure characteristics: Longer procedure time but shorter fluoroscopy time compared to RF
• Recurrence risk: Higher recurrence rate (15% vs 3.4% with RF) 3, 2

Pulsed Field Ablation (PFA)

• Currently lacks substantial evidence for AVNRT treatment
• No direct comparative studies with RF or cryoablation for AVNRT in the provided evidence
• Remains investigational for this specific arrhythmia

Clinical Decision Algorithm

1. For most adult patients with symptomatic AVNRT:

   • RF ablation offers the highest long-term success rate and should be considered first-line 1, 2

2. For patients with higher risk of AV block:

   • Consider cryoablation in:
     • Young patients
     • Patients with pre-existing conduction abnormalities
     • Cases where the ablation target is very close to the AV node 3, 2

3. For recurrent AVNRT after initial ablation:

   • RF ablation should be considered due to lower recurrence rates 2

Important Considerations and Caveats

• Risk-benefit assessment: The slightly higher success rate of RF must be weighed against the small but real risk of permanent AV block requiring pacemaker implantation
• Operator experience: Success rates and complications are influenced by operator experience with each technology
• Long-term outcomes: RF ablation has more extensive long-term follow-up data compared to cryoablation and especially PFA
• Technology evolution: Newer RF catheters with contact force sensing and improved mapping may further reduce complications

The decision between RF and cryoablation should consider patient age, anatomy, and risk tolerance, while PFA requires more evidence before it can be recommended for routine AVNRT treatment.