LEFT ATRIAL FUNCTION AND OUTCOME OF CATHETER ABLATION IN PATIENTS WITH ATRIAL FIBRILLATION: A MAGNETIC RESONANCE STUDY

Background The effects of atrial fibrillation (AF) catheter ablation on the left atrium (LA) are poorly understood. Objectives To examine short- and long-term associations of AF catheter ablation with LA function using cardiac magnetic resonance (CMR). Methods Fifty-one AF patients (mean age 56 +/- 8 years) underwent CMR at baseline, 1 day (n = 17) and 11 +/- 2 months after ablation (n = 38). LA phasic volumes, emptying fractions (LAEF), and longitudinal strain were measured using feature-tracking CMR. LA fibrosis was quantified using late gadolinium enhancement (LGE). Results There were no acute changes in volume; however, active, total LAEF, and peak LA strain decreased significantly compared to the baseline. During long-term follow-up, there was a decrease in maximum but not minimum LA volume (from 99 +/- 5.2 ml to 89 +/- 4.7 ml; p = .009) and a decrease in total LAEF (from 43 +/- 1.8% to 39 +/- 2.0%; p = .001). In patients with AF recurrence, LA volumes were unchanged. However, total LAEF decreased from 38 +/- 3% to 33 +/- 3%; p = .015. Patients without AF recurrence had no changes in LA functional parameters during follow-up. The amount of LA LGE at long-term follow-up was higher compared to the baseline, however, was significantly less compared to immediately post-procedure (37 +/- 1.9% vs. 47 +/- 2.8%; p = .015). A higher increase in LA LGE extent compared to the baseline was associated with a greater decrease in total LAEF (r = -.59; p < .001). Conclusions LA function is impaired acutely following AF catheter ablation. However, long-term changes of LA function are associated positively with the successful restoration of sinus rhythm and inversely with increased LA LGE.