(CCSP056) ULTRA-LOW-TEMPERATURE CRYOABLATION FOR VENTRICULAR TACHYCARDIA: A SINGLE CENTRE EXPERIENCE

Background: Endocardial catheter ablation for ventricular tachycardia (VT) may fail owing to the inability to deliver transmural lesions. In order to create fully transmural lesions, ultra-low-temperature cryoablation (ULTC) has been developed which uses near-critical nitrogen and is able to generate temperatures as low as −196°C. We report a series of 18 cases that underwent ULTC at MUHC, representing the largest single center experience worldwide to date.

METHODS AND RESULTS: 18 patients with ischemic and nonischemic cardiomyopathy, with monomorphic drug-refractory VT who had failed at least one antiarrhythmic underwent VT ablation with ULTC at our institution. After a voltage map, the mapping catheter was replaced with the ULTC catheter. ULTC lesions were applied over a fixed duration of time (60–180 s), followed by at least a 60-second thaw and another application at the original duration (freeze-thaw-freeze). Duration of time was selected depending on the wall thickness of the left ventricle (LV) monitored with intracardiac echo (ICE) to achieve tissue depths of 4.5–7.5 mm.

Baseline left ventricular ejection fraction was 31.8 ± 9%, mean age was 70.6 ± 11 years; 94% were male. A total of 33 VTs were induced prior ablation (1.8 VT per patient). Mean procedure time was 2.9±0.6 hours, mean ablation time 43.2 ± 21 minutes and mean fluoroscopy time 26± 10 minutes. A total of 176 cryoablation lesions were delivered (9.7±5 lesions per patient). From 18 patients, only 1 remained inducible at the end of the procedure (this VT was not the clinical one and was not targeted) and in other 2 patients, repeat VT study was not performed post ablation. Complications included one pericardial effusion that required drainage. From 18 patients, 16 (88.9%) were discharged within the first 24 hours post ablation.

Conclusion: ULTC is feasible in patients with drug refractory monomorphic VT with favorable acute procedural success.