Sounding the warning on the potential for oesophageal injury resulting from use of the nMARQ™ for ablation of atrial fibrillation.

Catheter ablation of atrial fibrillation (AF) is now a commonly performed procedure throughout the world. Despite the widespread adoption of this procedure, it is well recognized that important limitations exist. These limitations include (i) less that optimal efficacy, especially when long-term success is considered; (ii) long procedure times and the requirement for considerable skill to perform the procedure safely and effectively; and (iii) a significant risk of complications, some of which may be life threatening. One of the most feared and lethal complications of AF ablation is the development of an atrial oesophageal fistula. Although extremely uncommon (,0.1%), the devastating outcomes of this complication have resulted in great respect for this complication by all who perform AF ablation procedures. The nMARQTM (Biosense Webster), a mutielectrode irrigated circular ablation catheter, has recently been developed with the aim of making AF ablation quicker, easier, safer, and as effective, or more effective than ablation strategies using a standard point-by-point approach or cryoballoon ablation. In this issue of EP-Europace, Rillig et al. report the incidence of oesophageal injury with the nMARQTM ablation catheter using two different ablation strategies. The nMARQTM catheter is available as a 10 pole (nMARQTM circular) or 7 pole (nMARQTM crescent) mapping and irrigated ablation catheter that allows simultaneous ablation from all (or selected) poles to create a circumferential ablation line while mapping the changes in pulmonary vein (PV) potentials to confirm isolation. The nMARQ circular and crescent catheters both have equidistant 4 mm interelectrode spacing and have distinct loop diameters of 20–35 and 20–40 mm, respectively. A total of 21 patients (66% men; 62+9 years) with symptomatic, drug refractory paroxysmal (32%) or persistent (62%) AF underwent PV isolation with radiofrequency (RF) ablation using the nMARQTM catheter. Over 98% of PVs (83 of 84) were isolated. All patients underwent continuous oesophageal temperature monitoring using a 7Fr oesophageal temperature probe (SensithermTM; St. Jude Medical) with three thermistors spaced 5 mm apart that can report temperature changes within 0.5 s. The temperature probe was advanced to the level of the left atrium under fluoroscopic guidance at the start of the procedure and its position was repeatedly adjusted during ablation such that the sensors were adjacent to the respective ablation site. Oesophageal temperature was continuously monitored and RF delivery was immediately halted if the oesophageal luminal temperature exceeded 418C. Further ablation was performed at the same site, if needed, once the temperature returned to baseline. As part of the protocol, endoscopy was performed in all patients 2 days after ablation to screen for oesophageal injury, which was characterized as minimal lesion (erythema with intact mucosa), ulceration, or perforation. When the study started, a standardized protocol was used forenergydeliveryon the posterior wall which involveddelivery of RF for a maximum duration of 60 s using a maximum power of 20 watts (W) for bipolar ablation and 10 W for unipolar ablation. Among the first six patients, oesophageal injury was observed in 50% of the patients; two patients developed minimal lesions and one had ulceration. Because of this high incidence of oesophageal injury, the operators modified their protocol for energy delivery on the posterior wall. They reduced RF delivery and duration to a maximum power of 15 W and 10 W for unipolar and bipolar ablation, respectively, for 30 s. Among the second group of patients, only 1 of 15 (6.7%) patients developed a minimal oesophageal lesion (P 1⁄4 0.053). Notably, in both groups, ablation was discontinued with a temperature rise above 418C; however, the maximum oesophageal temperature reached in group 1 was 42.48C and group 2 was 42.58C (P 1⁄4 0.16). This study that evaluated the safetyandefficacyof AFablation using a novelmultipolar irrigated ablation catheter is awelcome addition to the literature. In writing this editorial we are charged with helping to