Ablation of Premature Ventricular Contractions Using a Novel Ultra-Low-Temperature Cryoablation System – A Case Series

Background

Ablation of premature ventricular contractions (PVC) can be very challenging. Conventional ablation using radiofrequency (RF) energy is limited by lesion depth. Recently a novel ultra-low-temperature cryoablation (ULTC) system utilizing -196°C nitrogen (N2) cryogen has been introduced allowing deeper lesions, titration of lesion depth and stable catheter position. This may be of particular interest in patients with PVCs originating from intramural or epicardial target regions, in patients with previously failed endocardial ablation as well as PVCs originating from papillary muscles.

 

Aim 

The aim of this prospective case series was to evaluate the safety and efficacy of a novel ULTC system in patients with highly symptomatic PVC or PVC induced ventricular tachycardia (VT). 

 

Methods 

Consecutive patients undergoing ablation of PVC by means of ULTC were prospectively enrolled at a tertiary ablation center between April and June 2024. Patient characteristics, procedural data, as well as safety and efficacy during short-term follow-up are reported.

 

Results 

A total of three consecutive male patients with PVCs and underlying cardiomyopathy [aged 62 ± 9 years, LVEF 45 ± 11 %, mean PVC burden 18 ± 1%] were included. Two patients had an ICD with ICD interventions for sustained VT. All patients had a history of at least two previous PVC ablation procedures using RF energy in the past 10 years. 

Mapping and ablation procedures were performed with the use of a three-dimensional mapping system using an antegrade approach via transseptal puncture. Sustained VT could be induced in two patients. Substrate and activation mapping of the left ventricle (LV; n=3) and right ventricular outflow tract (RVOT; n=1) were performed using a high-density mapping catheter. In addition, pace mapping was performed using the high-density mapping catheter as well as the ULCT ablation catheter. Patient #1 underwent ablation of two PVC target regions (LV summit and posteroseptal RVOT) and additional substrate modification in the anteroseptal LVOT, patient #2 ablation of one PVC (inferobasal LV) with additional substrate modification for several induced VTs inferolateral and apical LV and patient #3 ablation of two PVCs (LV inferoseptal basal and anterosuperior LV FIGURE 1). With respect to acute procedural success all clinical PVCs and VTs could be successfully ablated.

Mean procedure duration was 144 ± 17 min, with a mean freeze duration of 38 ± 4 minutes, a mean minimum freeze temperature of  -156 ± 13 °C and a lowest freeze temperature of -172 °C. 

No minor or major acute periprocedural or postprocedural complications were observed. PVC burden detected by 24-hour Holter ECG after ablation was reduced to 3±2%. No sustained VT or ICD intervention occurred during short-term follow-up 5± 11 days.

 

Conclusion: 

Ablation of PVCs by means of a novel ULTC ablation system could be performed safely and effectively in patients with previously failed RFC ablation procedures. Longer follow-up data and larger patients cohorts are needed to assess long-term outcomes. Furthermore, randomized trials are necessary to compare directly radiofrequency- and ULTC ablation.