RESUMO
INTRODUCTION: Atrioventricular nodal reentrant tachycardia (AVNRT) is the most common supraventricular tachycardia referred for ablation. High success rates have been accompanied with a small risk of atrioventricular (AV) block. Cryoablation has been used as an alternative to radiofrequency (RF) ablation, but studies have been underpowered in comparing the 2 techniques. METHODS AND RESULTS: An electronic search and hand-search of reference lists for published and unpublished data was carried out. Comparative studies (cohort and randomized controlled trials) of RF versus cryoablation for AVNRT were identified independently by 2 reviewers. Searches were limited to English language human studies. The primary metameter was long-term AVNRT recurrence (>2 months postprocedure and ECG/electrophysiology study [EPS]-documented) and secondary metameters included acute procedural failure and AV block requiring pacing. A total of 5,617 patients in 14 trials were included in this systematic review. Acute procedural failure with cryoablation was slightly higher than with RF ablation, but the difference was not statistically significant (risk ratio [RR] 1.44 [95% confidence interval; CI 0.91-2.28], P = 0.12). Long-term recurrence was higher with cryoablation (RR 3.66 [95% CI 1.84-7.28], P = 0.0002) even after adjusting for larger (6 mm) cryocatheter tips, "insurance lesions" and longer (>6 months) follow-up duration. RF ablation for AVNRT was associated with permanent AV block in 0.75% of patients, but was not reported in any patients treated with cryoablation (n = 1066, P = 0.01). CONCLUSIONS: Cryoablation is a safe and effective treatment for AVNRT. Although late-recurrence is more common with cryoablation than with RF ablation, avoidance of permanent AVN block makes it an attractive option in patients where the avoidance of AV block assumes higher priority (such as children and young adults).