NEW YORK (Reuters Health) – In the short term, cryoablation for atrioventricular nodal reentrant tachycardia (AVNRT) is as effective as radiofrequency catheter ablation, but 6-month recurrence rates are higher with cryoablation, a German team reports in the November 30 issue of Circulation.

The authors note that the main complication of RF catheter ablation of the slow AV nodal pathway is inadvertent damage to the fast pathway, causing permanent AV block. Tissue destruction can be more controlled with the cryoablation catheter and might therefore be safer than RF ablation.

After comparing the two approaches, however, the investigators found the disadvantages of cryoablation outweighed its advantages. “In future, we will use cryo-energy for AVNRT only in anatomically difficult cases and in small children, because in these cases, the potential safety advantage of cryoablation seems important,” Dr. Isabel Deisenhofer told Reuters Health in an email.

For their study, Dr. Deisenhofer with Deutsches Herzzentrum Munchen and her colleagues randomly assigned 509 patients with AVNRT to slow pathway cryoablation or radiofrequency catheter ablation (RFCA). Results were almost identical in the two groups in terms of immediate ablation success (96.8% versus 98.4%) and occurrence of permanent AV block (0% versus 0.4%), according to the report.

However, Dr. Deisenhofer pointed out, “Significantly more patients in the cryoablation than in the RFCA group experienced AVNRT recurrence (9.4% vs. 4.4%; p=0.029), leading to a significant difference of the combined primary endpoint of ablation success, AV-block and AVNRT recurrence.”

Cryoablation was associated with lower pain perception, but pain scores were relatively low in both groups — 20.3 in the RFCA group versus 7.3 in the cryoablation group, on a pain perception scale of 0 (no pain) to 100 (maximum pain).

While less pain perception with cryoablation is an advantage, it’s “counterbalanced by longer procedure times and frequent device functionality failure,” Dr. Deisenhofer commented.

Summing up, she concluded: “Cryoablation in patients with AVNRT is associated with a comparably high acute success rate as RF. However, the significantly higher recurrence rate after cryoablation is probably the main limitation of using this energy form for AVNRT ablation, especially as the potential safety benefit of cryoenergy seems negligible.”

Reference:

Cryoablation Versus Radiofrequency Energy for the Ablation of Atrioventricular Nodal Reentrant Tachycardia (the CYRANO Study)

Circulation 2010;122:2239-2245.