Impact of Atrial Remodeling on Heart Rhythm After Radiofrequency Ablation and Mitral Valve Operations

Background. This study was conducted to determine the effect of left atrial structural remodeling on heart rhythm after radiofrequency ablation concomitant to mitral valve operation. Methods. Sixty-six consecutive patients with of atrial fibrillation (AF) and mitral valve disease underwent radiofrequency ablation and mitral valve operation. Heart rhythm was evaluated before and at 3, 6, and 12 months postoperatively. Biopsy specimens of the posterior wall of the left atrium were evaluated for the extent of fibrosis, myocyte diameter, intensity of inflammatory infiltrates, degree of myocytolysis, and capillary density. Results. Ten patients died and 1 patient was lost to follow-up. Heart rhythm at 12 months was used to divide the remaining 55 patients into two groups: group I, 34 with sinus rhythm; group II, 21 with AF. Paroxysmal AF preoperatively was more frequent among group I patients, and persistent/long-standing persistent AF in group II (p = 0.0006). Groups I and II differed significantly in myocyte diameter (17.9 +/- 3.5 vs 20.3 +/- 4.6 mu m, p = 0.04), fibrosis percentage (38.7% +/- 11.2% vs 47.6% +/- 12.3%, p = 0.009), inflammatory infiltrates (p = 0.02), and preoperative left atrial diameter (5.03 +/- 0.7 vs 5.5 +/- 0.8 cm, p = 0.04). No differences were found in capillary density (797.9 +/- 500.6 vs 946.0 +/- 373.7/mm(2), p = 0.3) and myocytolysis (p = 0.4). Multivariate analysis showed myocyte diameter (p = 0.047) and fibrosis (p = 0.014) were independent predictors for an AF persistence at 12 months. Conclusions. Left atrial structural remodeling strongly affects heart rhythm after concomitant radiofrequency ablation and mitral valve operation. (Ann Thorac Surg 2012;93:1449-55) (c) 2012 by The Society of Thoracic Surgeons