Abstract 2156: Left Atrial Fibrosis Impacts Left Ventricular Ejection Fraction in Patients with Atrial Fibrillation
Background. The extent of left atrial (LA) wall fibrosis detected by delayed enhancement MRI (DE-MRI) appears to be correlated with advanced atrial fibrillation (AF). However, the effect of LA fibrosis on left ventricular function (LVEF) is not well understood. We report the relationship between left atrial fibrosis and LVEF in patients with AF.
Methods. Sixty-seven patients underwent DE-MRI and 2-dimensional trans-thoracic echocardiography prior to ablation for AF. Three dimensional segmentation of the LA was performed and the extent of fibrosis was quantified using a semi-automated algorithm. Patients were assigned to one of three groups based on the degree of LA fibrosis; 1) mild enhancement where the fibrosis < 15% of the LA wall, 2) moderate enhancement where fibrosis > 15% and < 35%, and extensive where fibrosis > 35% of the LA wall. LVEF was determined both prior to and 3 months following pulmonary vein antrum isolation with posterior wall and septal debulking.
Results. The average pre-ablation LVEF among patients with mild fibrosis was 53.2% ± 9.9% (n = 41), 52.3% ± 7.4% (n = 19) among patients with moderate fibrosis and 42.1% ± 9.9% (n = 7) among those with extensive enhancement (p = 0.01,one way ANOVA). The difference remains significant after controlling for patient age, gender, hypertension, MI, AF type, mitral valve regurgitation, CAD and the presence of non-AF related CHF. Following ablation, all groups had an increase in the LVEF. The greatest increase occurred among patients in the extensive group. On average, this group experienced an overall improvement of 10.8% ± 14.1%. Patients in the mild enhancement group had an average improvement of 3.3% ± 11.1% and those in the moderate group had an average improvement of 3.8% ± 5.6%. The post-ablation LVEF among patients with mild fibrosis was 56.6% ± 8.3%, 56.2% ± 6.4% among patients with moderate fibrosis and 53.0% ± 15.4% among patients with extensive fibrosis.
Conclusion. From our preliminary experience with DE-MRI fibrosis detection, patients with extensive LA fibrosis appear to have depressed LV function pre-ablation. This group of patients seems to experience a large improvement (~11%) in LV function post-ablation compared to patients with less LA fibrosis.