AUSTIN, TEXAS. Catheter ablations for atrial fibrillation (AF) are usually performed with the patient under conscious sedation, that is, awake, but sedated to minimize pain and movement during the procedure. The most commonly used agents used in achieving conscious sedation are a combination of fentanyl (an opium-like drug) and midazolam (a benzodiazepine). The conscious sedation approach unfortunately does not guarantee that the patient will keep still or that their breathing will be regular – both important factors in ensuring catheter contact and stability. In order to overcome these shortcomings, several electrophysiologists (EPs) now use general anesthesia when performing catheter ablations for AF.

A team of EPs from St. David's Medical Center and California Pacific Medical Center now report the results of a randomized study to compare the efficacy and long-term outcome of ablation procedures performed using general anesthesia with that of similar procedures using conscious sedation. The study included 257 patients with paroxysmal AF who were randomly assigned to undergo a pulmonary vein antrum isolation procedure (PVAI or Natale protocol) with conscious sedation (group 1 – 128 patients) or general anesthesia (group 2 – 129 patients). The average age of the patients was 59 years, 75% were male, and 86% had lone AF (no coronary heart disease).

A combination of electrophysiologic mapping and intracardiac echocardiograms (ICE) was used to guide the ablation with a 3.5-mm irrigated-tip catheter. An esophageal temperature probe was also used to prevent damage to the heart wall adjacent to the esophagus. All patients underwent complete pulmonary vein isolation after which the catheter was positioned at the junction of the right atrium and the superior vena cava where mapping and ablation was performed in 86% of patients. Additional non-pulmonary vein triggers were ablated in 11% of group 1 patients and in 10% of group 2. Follow-up examinations were performed at 3, 6, 9 and 12 months after the procedure and included 7-day Holter monitoring. Recurrence was defined as any episode of AF or tachycardia lasting for at least 30 seconds after an 8-week blanking period.

At an average of 17 months after the initial procedure, 69% of group 1 were free of arrhythmia without the use of antiarrhythmic drugs as compared to 88% of group 2 patients. The only variable independently associated with freedom from recurrence was the use of general anesthesia. Recurrence was experienced by 31% of group 1 patients and 12% of group 2 (general anesthesia) patients. All underwent a second procedure during which it was discovered that 42% of ablated pulmonary veins in group 1 had recovered conduction as compared to only 19% in group 2. Fluoroscopy and total procedure time were significantly shorter in group 2 (53 minutes and 2.4 hours respectively) than in group 1 (84 minutes and 3.6 hours). No major complications were observed in either group.

The study authors attribute the better outcome for procedures performed under general anesthesia to greater stability of the ablation catheter resulting from the fact that the patient is immobile and breathing is regular.

Di Biase, L, Natale, A, et al. General anesthesia reduces the prevalence of pulmonary vein reconnection during repeat ablation when compared with conscious sedation: Results from a randomized study. Heart Rhythm, Vol. 8, March 2011, pp. 368-72