RESUMO
METHODS AND RESULTS: This study included 68 patients (47 men, 21 women, mean age 69 years) in whom atrial fibrillation (AF) recurred immediately after electrical cardioversion (EC) was performed with no antiarrhythmic drugs. After administration of cibenzoline (Cib, 70 mg) or pilsicainide (Pil, 50 mg) on a randomized basis, all patients again underwent EC at the same energy as that prior to administration of antiarrhythmic drugs. We compared the efficacy of Cib (n = 35) and Pil (n = 33), and examined factors affecting successful cardioversion in patients treated with Cib. These patients were divided into a successful group (Group A) and an unsuccessful group (Group B). The success rate of EC at the same energy after intravenous Cib administration (77%) was significantly greater than that after intravenous Pil administration (42%) (p < 0.01). In patients treated with Cib, AF duration was significantly greater in Group B (55.8 ± 48.2 h) than in Group A (29.1 ± 17.0 h) (p < 0.05). Plasma concentrations of atrial natriuretic peptide (ANP) during AF and the ratio of ANP level during AF to that during sinus rhythm were also significantly greater in Group A (110.9 ± 69.7 pg/ml and 3.9 ± 2.8, respectively) than in Group B (58.2 ± 36.1 pg/ml and 1.8 ± 0.9, respectively) (both, p < 0.05). In patients treated with Pil, AF duration was also significantly greater in Group B (59.7 ± 44.6h) than in Group A (19.6 ± 21.7 h) (p < 0.05), and the ratio of ANP level during AF to that during sinus rhythm was significantly greater in Group A (3.5 ± 2.6) than in Group B (1.7 ± 0.9) (p < 0.05). CONCLUSIONS: In patients with AF previously refractory to conventional EC, intravenous Cib administration was more effective in restoring sinus rhythm with EC than intravenous Pil administration. The capacity of ANP secretion during AF tachycardia may be a predictive indicator for the prevention of AF recurrence in electrically remodeled atria.
