Prospective Multicenter Experience With Cooled Radiofrequency Ablation Using High Impedance Irrigant to Target Deep Myocardial Substrate Refractory to Standard Ablation

Objectives: This study sought to evaluate the efficacy and safety of using half-normal saline (HNS) as the cooling radiofrequency ablation (RFA) irrigant among patients who had failed prior, standard RFA. Background: Effective control of ventricular arrhythmias that arise from mid-myocardium may be refractory to standard RFA. Recent data suggest that delivering fluid with decreased ionic concentration during open-irrigated RFA can produce deeper RFA lesions. Methods: A 12-center prospective analysis was performed of all ablations using HNS for the treatment of ventricular arrhythmias (premature ventricular complex [PVC]/ventricular tachycardia [VT]) refractory to standard ablation with normal saline irrigant. Results: HNS RFA was used clinically to target 94 PVC/VTs refractory to standard ablation. Acute success was achieved in 78 of 94 (83%), with longer-term success occurring in 78 subjects after a mean follow-up of 6.1 ± 6.7 months (range, 3.0 to 25.2 months). Steam pops were observed among 12 (12.6%) patients. There were no significant changes in electrolytes measured before and after the use of HNS, and there were no complications related to HNS use. Conclusions: The use of HNS instead of normal saline irrigant during high-power delivery targeting deep myocardial substrate is safe and effective. PVC/VT sources previously unaffected by standard ablation may be successfully ablated with improved efficiency of radiofrequency delivery using HNS.