www.af-symposium.org Atrial Fibrillation Ablation using Cryothermy: Comparisons with Radiofrequency Daubert, James Levine, Ethan Budzikowski, Adam Rationale for Nonpharmacologic Treatment of Atrial Fibrillation Atrial fibrillation is the most common symptomatic arrhythmia with a total incidence of 2.2 million cases in the United States alone [1]. The number of people with atrial fibrillation has been, and is expected to continue increasing; in fact, the number of affected people in the US alone is expected to more than double by the year 2050. [2, 3] The increased incidence is due in part to the increasing age of the population and also due to the increasing number of myocardial infarction survivors and perhaps also to the obesity epidemic (4). Additionally, there are data from the European community showing a similar incidence of atrial fibrillation in that cohort (5) Recent large randomized studies, including the AFFIRM and RACE trials, have failed to show an advantage of pharmacologic attempts at sinus rhythm restoration over rate control. All of these studies suggest that rate control may be a reasonable or even preferable option. However, there are two countervailing factors, a known increased mortality associated with atrial fibrillation and persistent symptoms associated with the condition. First, population based studies have consistently shown an increased mortality by a factor of 1.5-1.9 times [6] in patients with atrial fibrillation as compared to matched patients without atrial fibrillation (7). This suggests that the absence of improved or reduced mortality in the rhythm control arms of the randomized studies may be due to combination of very little success in restoration and maintenance of sinus rhythm, and/or the possible toxic effects of the medications. It remains to be proven, however, that successful restoration of sinus rhythm over the long term would result in a return of mortality reduction. A single center nonrandomized study from Milan, Italy (8) did suggest that atrial fibrillation ablation resulted in reduced mortality when compared to a matched group treated medically but it is not clear if the ablation and medically managed groups really were equivalent in underlying risks. The study from Taiwan published by Hsi E.H. (9) compared a nonrandomized group of elderly patients undergoing either catheter ablation for atrial fibrillation or AV junction ablation and permanent pacing. There were approximately 35 patients in each group. The freedom from symptomatic atrial fibrillation was better in the AV junction ablation group than in the ablation group, 100% vs 80%. However persistent atrial fibrillation was present in follow-up in close to 70% of patients in the AV junction ablation group versus only 8% in the pulmonary vein isolation group. Perhaps as a consequence of the persistent atrial fibrillation, heart failure