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Study reveals effectiveness of cryoablation in setting of atrioventricular nodal reentrant tachycardia
Deisenhofer I. Circulation. 2010;122:2239-2245.
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Data from a multicenter, prospective, randomized trial have shown cryoablation to be as effective as radiofrequency catheter ablation for atrioventricular nodal reentrant tachycardia for the short term. However, cryoablation resulted in a higher recurrence rate at the 6-month follow-up.
Trial investigators analyzed 509 patients who underwent slow pathway cryoablation (n=251) or radiofrequency catheter ablation (RFCA; n=258) at six centers in Europe and one center in China. They defined the primary endpoint as permanent atrioventricular block, immediate ablation failure and atrioventricular nodal reentrant tachycardia (AVNRT) recurrence throughout the 6-month follow-up, whereas secondary endpoints included procedural parameters and device functionality.
During follow-up, more patients in the cryoablation arm reached the combined primary endpoint than in the RFCA arm (12.6% vs. 6.3%; P=.018), despite immediate ablation success and occurrence of permanent atrioventricular block rates not differing between groups. AVRNT recurrence was also significantly higher in the cryoablation group (9.4% vs. 4.4%; P=.029).
Additionally, secondary endpoints, including procedure time (122.6 ± 43.7 minutes vs. 140.5 ± 56.4 minutes) and device functionality failure (two patients vs. 13 patients), favored the RFCA group, whereas the subjective pain score favored cryoablation (7.3 ± 13.9 vs. 20.3 ± 22).
“Cryoablation in patients with AVNRT is associated with a comparably high immediate success rate as [radiofrequency]. However, the significantly higher recurrence rate after cryoablation is probably the main limitation of using this energy form for AVNRT ablation, especially because the potential safety benefit of cryoenergy seems negligible,” the investigators wrote. – by Brian Ellis
What do we learn from this study? Positive outcomes for both techniques occurred:
- Cryoablation in patients with AVNRT is associated with a short-term success rate as high as that for RFCA.
- There is a significantly higher recurrence rate after cryoablation.
- There is less pain perception with cryoablation.
- Procedure times are longer and device failure more frequent with cryoablation.
Although the difference in recurrence rates reached significance, the absolute numbers are not that striking (eg, there is a roughly 95% long-term success rate with RFCA and a 90% success rate with cryoablation). For an individual patient, both strategies might have merit. In a young patient in whom permanent pacemaker implantation might be onerous, an initial attempt using cryoablation seems reasonable. We learn nothing from this trial about repeat procedures, and either technique might be used as a second try if failure occurs. There is no doubt that RFCA is readily available, straightforward and cheaper, but this study does not convince me that cryoablation should be relegated to the dust bin.
– Peter C. Block, MD
Cardiology Today Section Editor
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