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. (C) 2018 by the American College of Cardiology Foundation.