Reverse remodeling of the atria in patients with rheumatic mitral stenosis: impact of balloon mitral commissurotomy plus atrial fibrillation ablation

Abstract

Abstract Introduction Chronic Atrial stretch is an important determinant for atrial fibrillation (AF) in patients with rheumatic mitral stenosis (RMS). Purpose We analysed the effect of balloon mitral commissurotomy (BMC) plus atrial fibrillation ablation on the long-term occurrence of AF as compared to isolated BMC. Methods We prospectively included 20 patients with severe RMS undergoing BMC+AF ablation (Intervention) and compared it with a retrospective sample of 53 RMS patients that underwent BMC (Control). AF ablation consisted in pulmonary vein isolation and driver ablation identified using intracardiac basket mapping. We followed patients for 1 year after the procedure in both groups. Clinical values were evaluated in both groups. Propensity score matching was computed in order to evaluate the effect of the intervention and to analyse the impact of clinical properties of each group. Results At baseline, there were no statistical differences in gender (90% vs. 85%) and mitral valve area (1.2±0.18 vs. 1.17±0.18 cm2) between intervention and control groups, respectively. In contrast, there were differences in age (65±12 vs. 72±12; p=0.01) and AF incidence prior to the procedure (90% vs. 62%; p=0.001) between intervention and control groups, respectively. Patients undergoing AF ablation underwent successful pulmonary vein isolation in all cases and driver ablation at sites located in the right atrium (RA) in 7 (35%) patients. Median dominant frequency was significantly higher in the right atrium (DF RA 4.9±0.6 vs. DF LA 3.9±0.7 Hz; p=0.003) prior the intervention. After the intervention, it was significantly reduced only in the left atrium (LA) (DF RA 4.5±1 vs. DF LA 3.2±0.6 Hz; p=0.02 for Pre vs. Post DF LA). Three (15%) patients converted to sinus rhythm during ablation, the remaining were cardioverted. After 1-year follow-up, the proportion of patients in sinus rhythm was significantly higher in patients undergoing BMC+AF (90%) vs. isolated BMC (45%; p<0.001) (Graph). In the isolated BMC group, 4 patients converted to sinus rhythm and 1 patient in sinus rhythm prior to the procedure converted to AF at 1-year. Conclusion This observational study demonstrates that the combination of BMC+AF ablation significantly increses the proportion of patients in sinus rhythm at 1-year as compared to isolated BMC. Reverse remodelling of the atrial substrate following isolated BMC also converted to sinus rhythm a small proportion of patients with persistent AF at baseline. Thus, although reversal of atrial stretch changes by BMC could potentially terminate AF in some patients, the combined intervention with catheter ablation will successfully maintain sinus rhythm in the majority of patients in the study. Funding Acknowledgement Type of funding source: Public grant(s) – National budget only. Main funding source(s): FIS by Instituto de Salud Carlos III