Purpose: Pulmonary vein (PV) isolation has become the mainstay of catheter treatment of atrial fibrillation (AF). For an optimal procedural success, wide and complete linear lesions around the PVs are necessary. For this purpose, the CoolLoop circular cryoablation catheter (AFreeze; Innsbruck / Austria) was developed. In this study we evaluated the feasibility and safety of this ablation system for the first time in humans.
Methods: 10 patients (6M/4F; 61.3±9.5y) with symptomatic paroxysmal AF refractory to at least 1 AAD and without significant heart disease were included in 2 Austrian centres. The CoolLoop catheter was positioned at each PV antrum by guidance of intracardiac echocardiography (ICE). Subsequently, 2-4 double-freezes were performed for 5 min, respectively. PVI was confirmed with a circular mapping catheter. During cryoablation (CA) of the right PVs, phrenic nerve pacing was used to monitor phrenic nerve function.
Results: The CoolLoop catheter (figure) could positioned at all PV antra of all patients. A mean of 5.6±1.8 CA were performed in the LSPV, 5.6±1.6 in the LIPV, 6.3±2.5 in the RSPV and 5.4±1.6 in the RIPV. Mean procedure time was 231.7±48.4min and mean fluoroscopy time was 39.3±13.3min. 6/10 LSPV, 6/10 LIPV, 5/10 RSPV and 6/10 RIPV could be isolated exclusively using the novel cryoablation system. 1 patient developed groin hematoma and a brief episode of ST-elevation due to air embolism was observed in another patient. No other clinical complications and no phrenic nerve palsy occurred during 3 months of follow up.
Conclusions: Cryoablation for paroxysmal atrial fibrillation using the CoolLoop catheter system is feasible and safe. Clinical medium and long term efficacy still needs to be evaluated and to be compared with other catheters for ablation of AF.