In a small, randomized trial comparing the two techniques, cryoablation proved significantly less painful to patients than radiofrequency (RF) ablation when used to ablate the cavotricuspid isthmus (CTI). The cold technique did take slightly longer but was just as effective, although the study's small size will require a larger trial to verify efficacy.

Dr. Carl Timmermans and his colleagues at the Academic Hospital Maastricht randomized 14 consecutive patients with type I atrial flutter to receive either RF ablation or cryoablation. Patients were asked to evaluate pain using a visual analog scale (VAS).
Ablation was successful for all patients except one from the RF group who had incomplete blockage, a nonsignificant difference. No one who was successfully ablated had recurrence at a 6-month follow-up.

There were significant differences in how the patients perceived the pain of the procedure. Only one patient in the cryoablation group perceived pain, while all seven in the RF group did. The proportion of applications perceived as painful in the total cryoablation group was also significantly lower, as was the average pain score per application reported on the VAS.

The cryoablation procedure did take slightly longer on average, just more than 4 h as opposed to 2.5 h for the RF technique. The difference did not reach statistical significance. The authors suggest the longer treatment time is mostly due to the fact that each application site in the cryoablation procedure involves a double application, 4 minutes long, while the RF technique is a single 90-second application. The authors suggest further studies into the need for so much time and repeated cryothermia delivery, since the longer procedure time is a criticism that has dogged the cryoablation technique.

“The present study is the first systematic evaluation in the non-sedated patient of pain associated with RF of the CTI,” the authors write. The authors argue that ablation without pain is of clinical importance when ablating sites such as the coronary sinus and the atria, even if patients are consciously sedated during those procedures.