Efeitos da associação da estimulação atrial dinâmica em duplo sítio atrial com atenolol na prevenção da fibrilação atrial recorrente

Abstract

Objective: Evaluate the effects of optimized atrial stimulation -OAS (dual-site atrial pacing, heart rate above the intrinsic rate, and specific functional algorithm), and the use of atenolol in preventing recurrent atrial fibrillation (AF). Primary endpoint: to quantify the rate of AF episodes. Secondary endpoints: assessment of quality of life, specific cardiovascular symptoms, rate of hospital admissions, rate of electrical and pharmacological cardioversions, and adverse cardiac events. Methods:Twenty-five patients with recurrent episodes of paroxysmal AF and sinus node disease had dual-site atrial and ventricular pacemakers implanted, and were started on atenolol, 100 mg/day. Next, they were randomized to two groups: GROUP I: first three months with OAS and the specific pacing algorithm (DAO) turned on, and three more months with the algorithm off. GROUP II: the inverse sequence to GROUP I. The pacing mode chosen was DDDR, and after three months patients underwent clinical and electronic evaluations of the stimulation system by: automatic mode switch (AMS), 24-hour Holter monitoring, Doppler echocardiogram, and SF-36 questionnaire. Following, a crossover comparison took place, and a new assessment was performed six months later.Results: When compared to the group with the algorithm turned off, OAS patients had lower rates of: AF/week (p < 0.001); AMS activations (p < 0.01); hospitalizations (p < 0.001); cardioversions (p < 0.001), and higher scores on the physical and mental components of quality of life. Conclusion:The hybrid therapy adopted, OAS associated with the use of atenolol, reduced the rate of recurrent AF and improved the clinical-functional status of patients with symptomatic bradyarrhythmias.Key words: Dynamic atrial overdrive, recurrent atrial fibrillation, prevention of atrial fibrillation, dual-site atrial pacemaker. AF is currently the biggest challenge for researchers in the area of cardiac arrhythmias, as it entails considerable morbimortality and with an incidence estimated to be 0.4% in the general population, and up to 5.9% in those above 65 years of age. It is the most common sustained cardiac arrhythmia, and its morbidity correlates with thromboembolic phenomena, with the loss of atrioventricular synchronism and with the maintenance of high heart rates, besides being considered the leading cause of cerebrovascular accidents 1,2 .Multisite atrial stimulation has been used to prevent atrial tachyarrhythmias, as there are evidences that it not only suppresses automatic triggering sites, but it may also have a direct effect on the mechanisms of sustained AF [3][4][5][6] . DDDR stimulation with a minimum frequency programmed to 60 ppm, and a dynamic atrial overdrive algorithm (DAO) seem also capable of reducing symptomatic AF in patients with combined SND and AF 7,8 . On the other hand, dual-site atrial stimulation and conventional stimulation alone do not seem to be sufficient for the treatment of AF. The association of dual-site atrial stimulation with atrial overdrive algorithms and ß-b...