Cardiac ablation and mapping 


The ICY-AVNRT trial evaluated the safety and effectiveness of the Freezor™ Xtra cardiac cryoablation catheter for the treatment of patients with AVNRT.

Three healthcare professionals wearing scrubs and protective gear while looking down

Study purpose and design

The ICY-AVNRT trial is a prospective, unblinded, multicenter, single-arm, nonrandomized study evaluating the use of the Freezor Xtra cardiac cryoablation catheter for the treatment of AVNRT; 397 patients enrolled from 36 centers in the United States and Canada.

Freezor Xtra cardiac cryoablation catheter placed on top of a gray circle background

Key findings

Primary efficacy endpoint met

  • Acute success was achieved in 378 of 397 (95%) of subjects
  • Chronic success was achieved in 93% of subjects
Blue line graph showing primary efficacy endpoint key findings from the ICY-AVNRT trial

10 subjects (2.7%) had documented recurrent AVNRT over the six-month follow-up period, all of which occurred within three months of the index procedure.

Primary safety endpoint met

  • 4 of 397 (1.0%) subjects experienced a procedure-related safety event
  • Procedure-related safety events included:
    • One tamponade*
    • One pulmonary embolism*
    • One femoral vein hemorrhage*
    • One diagnostic EP catheter knotting*
  • AV block: First-degree AV block persisted beyond follow-up in one subject. No subject was symptomatic, and none required permanent pacing.
* None were related to catheter use.


of AVNRT cases resulted in permanent pacemaker implantation


of AVNRT cases experienced a primary safety event, none of which resulted from the Freezor™ Xtra catheter


at six months

Endpoint definitions


  • Acute success is defined as no more than a single echo beat after ablation with or without infusion of isoproterenol
  • Chronic success is defined as the composite of acute success and the lack of documented recurrent AVNRT during the six-month follow-up period



The primary safety endpoint is lack of a serious procedure-related or serious device-related adverse event during the study period

Study population

Key inclusion criteria

  • Documented SVT thought to be AVNRT (documented by ECG, transtelephonic, Holter, or event monitors)
  • Age 18+

Key exclusion criteria

  • History of a sustained VT
  • Presence of another supraventricular arrhythmia (SVT) that could be misinterpreted with AVNRT during follow-up
  • A reversible cause of SVT
  • A previous ablation for AVNRT
  • New York Heart Association (NYHA) class III or IV heart failure within the preceding 90 days
  • The presence of a permanent implantable cardiac rhythm device (including loop recorders)
  • History of AV conduction disturbances, including first-/second-/third-degree AV block or left bundle branch block

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