Cooling dynamics: a new predictor of long-term efficacy of atrioventricular nodal reentrant tachycardia cryoablation.

PURPOSE: Catheter ablation of the slow pathway is the most effective treatment for atrioventricular nodal reentrant tachycardia (AVNRT). Cryoenergy, compared to radiofrequency, relates to lower heart block risk but higher incidence of AVNRT recurrences. The aims of this study are to confirm the safety and efficacy of AVNRT cryoablation and to identify predictors of long-term recurrences.

METHODS

Among 241 patients undergoing AVNRT cryoablation, 239 (99.2%) experienced acute effective cryoablation of the slow pathway, and no procedure-related complications were reported.

RESULTS

After a follow-up of 44.9 ± 31.7 months, 28 (11.7%) patients presented AVNRT recurrences. A shorter preablation (p = 0.05) and postablation anterograde Wenckebach cycle length (p < 0.01), a shorter postablation atrioventricular node refractory period (p = 0.04), and persistence of the crossover sign (p = 0.03) were associated with higher incidence of long-term recurrences. Considering cooling dynamics, a longer time to reach temperature ≤-70 °C (p = 0.03) and a higher minimal temperature during ablation (p = 0.04) were related to recurrences. Patients without residual markers of dual AV node physiology (AH jump, single atrial echo beat, crossover) reported a lower recurrence rate (p = 0.05) compared to those without. At multivariate analysis, a longer time to -70 °C was the strongest independent predictor of long-term recurrence (OR 1.75, 95% CI 1.01-3.03, p = 0.04).

CONCLUSIONS

AVNRT cryoablation is safe and effective. Long-term recurrence rate was 11.7%. An ablation approach directed to the complete elimination of dual AV node physiology, along with assessment of the tissue's cooling dynamics, holds the potential to improve long-term AVNRT cryoablation efficacy.