Crioablação da fibrilação atrial: eficácia, segurança e análise da curva de aprendizado do método

Abstract

The electrical isolation of the pulmonary veins is recognized as a fundamental basis for the non-pharmacological treatment of atrial fibrillation (AF) and, therefore, has been recommended as an initial step in the ablation of AF in all guidelines. The cryo-energy balloon technique, although widely used in North America and Europe, is still at an early stage in many developing countries, such as Brazil. The objectives of our studies were to evaluate the success and safety of the cryoablation technique in our service, in patients with paroxysmal and persistent AF and the learning curve with this new technology. In the first study, one hundred and eight consecutive patients with symptomatic AF and refractory to pharmacological treatment, underwent cryoablation to isolate the pulmonary veins. The patients were separated into two groups, according to the conventional classification of AF: paroxysmal (lasting up to seven days); and persistent (AF for more than seven days). Procedure recurrence and safety data were analyzed as primary and secondary outcomes, respectively. Considering the evolution after the initial 3 months, 21 recurrences (19.4%) were observed in a period of one year of follow-up. The recurrence-free survival rates in the paroxysmal and persistent groups were 89.2% and 67.4% respectively. The mean procedure time was 96.5 ± 29.3 minutes and the mean fluoroscopy time was 29.6 ± 11.1 minutes. Five (4.6%) complications were observed, none of which were fatal. The level of significance adopted was 5%. The study showed results similar to others in the literature and concluded that cryoablation for electrical isolation of pulmonary veins is a safe and effective method for treating AF. In our second study, we evaluated the difference in the results of the procedure, depending on the team's learning curve. For this analysis, patients were divided into quartiles according to the chronological order of the procedures, with quartile one being the most remote and quartile four being the most recent. The distribution of the variables age, increase in AE, CHA2DS2VASc, classification of AF and recurrence rate in Blanking were similar between the quartiles and did not present a statistically significant difference. We observed a progressive decrease in the recurrence rate up to one year, a progressive decrease in the variables fluoroscopy time and AE time, and a progressive increase in the proportion of patients who reached established criteria for tissue injury efficacy (time for vein isolation less than 40 seconds and minimum cooling temperature below -40°C). In our second study, the evolutionary analysis of variables according to the dates of the procedures suggested a stabilization of the learning curve based on 100 procedures performed.