Catheter cryoablation of supraventricular tachycardia: results of the multicenter prospective "frosty" trial.
OBJECTIVE
To study the safety, efficacy, and mapping utility of a new cryoablation catheter.


BACKGROUND
The CryoCath Technologies Freezor catheter has been used successfully for cryoablation of supraventricular tachycardia (SVT), but has not been evaluated in a large clinical trial.


METHODS
A multicenter clinical trial to evaluate the safety, efficacy, and cryomapping utility of this cryoablation catheter was conducted in 166 subjects. The target of ablation was the slow pathway in patients with SVT due to AV nodal reentry (AVNRT, n = 103), an accessory pathway in patients with AV reentrant SVT (AVRT, n = 51) and the AV junction in patients with atrial fibrillation (AF, n = 12).


RESULTS
Acute procedural success (APS) was achieved in 83% of the overall group (95% CI, 76% to 88%). APS in the AVNRT group was 91% (98.3% CI, 82% to 97%), compared to 69% for AVRT (98.3% CI, 51% to 84%) and 67% for AF (98.3% CI, 29% to 93%), a highly significant difference (P < .001 by stepwise logistic regression). In patients with APS, long-term success after 6 months was 91% overall (95% CI, 86% to 96%) and 94% for AVNRT subjects (98.3% CI, 87% to 100%). None of the AVNRT or AVRT subjects required a permanent pacemaker. Cryomapping successfully identified ablation targets in 64% of patients in whom it was attempted. The electrophysiologic effects of cryomapping were completely reversible within minutes in 94% of such attempts.


CONCLUSIONS
Catheter cryoablation of SVT is a safe alternative to RF ablation and is clinically effective in patients with AVNRT. Cryomapping can reversibly identify targets for ablation and can help minimize the risk of inadvertent AV block during ablation.
Friedman
Peter L
PL
Cardiovascular Division, Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts, USA.
Dubuc
Marc
M
Green
Martin S
MS
Jackman
Warren M
WM
Keane
David T J
DT
Marinchak
Roger A
RA
Nazari
Jose
J
Packer
Douglas L
DL
Skanes
Allan
A
Steinberg
Jonathan S
JS
Stevenson
William G
WG
Tchou
Patrick J
PJ
Wilber
David J
DJ
Worley
Seth J
SJ
D000328:Adult; D017115:Catheter Ablation / Q000379:methods*; D016009:Chi-Square Distribution; D003452:Cryosurgery / Q000379:methods*; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications; D011446:Prospective Studies; D013617:Tachycardia, Supraventricular / Q000601:surgery*; D016896:Treatment Outcome