Background: We hypothesized that chronic atrial fibrillation (AF) originated from the pulmonary veins, and was maintained by irregular activations of the posterior left atrium. We had performed the box pulmonary vein isolation procedure for the elimination of chronic AF associated with solitary mitral valve disease from 1999 to 2004. This paper evaluated the long-term results of this procedure over more than 6 years, and discussed the role of the pulmonary veins and posterior left atrium in maintaining AF.
Methods: Fifty-three patients were examined after box pulmonary vein isolation procedure concomitant with solitary mitral valve surgery retrospectively. We divided the patients into two groups with or without the elimination of AF (AF group and non-AF group). The disappearance of AF was determined by electrocardiography, and atrial function was evaluated by transthoracic echocardiography. The elimination of chronic AF and the recovery of atrial systolic function after surgery were evaluated over more than 6 years of follow-up.
Results: In a total of 462.8 patient years of follow-up (range 6.3 to 11.5 years, mean: 8.9 ± 2.7 years), AF disappeared in 77.3% of the patients (41/53) at 3 months and in 70.6% (36/51) of the patients at 6 years after the box pulmonary vein isolation, respectively. Among the preoperative variables, a long duration of AF and a large diameter of the left atrium were the predictive factors for recurrences of AF (p <0.05). There was no left atrial tachycardia even though we did not perform ablation towards the mitral valve annulus.
Conclusions: The box pulmonary vein isolation procedure can terminate chronic AF associated with solitary mitral valve disease, and maintain a sinus rhythm for more than 6 years in 70% of chronic AF patients. This study implicates the pulmonary veins and posterior left atrium in maintaining chronic AF associated with mitral valve disease.