P1071Function assessment and volumetry of the left atrium in patients with idiopathic atrial fibrillation multimodal imaging with 3-dimensional echocardiography and 2-dimensional speckle tracking

Background: Atrial fibrillation (AF) is a multifactorial disease in mostly elderly patients. In contrast, idiopathic AF (iAF) is a disease entity without overt risk factors or structural heart disease in conventional imaging. It provides ideal conditions for a detailed assessment of the function of the left atrium (LA) and ventricle (LV)

Methods: The cohort of patients with iAF constituted of 39 subjects (5 women and 34 men; median age 44 (39/46,8) years). We defined iAF with a disease onset at a maximum age of 45 years, lack of relevant cardiovascular risk factors and unremarkable 2-dimensional echocardiogram. The CHA2DS2-VASc Score was 0 for every patient. In addition to conventional echocardiography, 3-dimensional volumetry of the left atrium (LA) and left ventricle (LV) were performed and combined with 2-dimensional speckle tracking. In secondary analyses, we dichotomized the cohort into a group without the need for ablation therapy according to current guidelines (group 1; N=9) and a catheter ablation group (group 2; N=30). Patients presented after 3 month to the last treatment procedure.

Results: Median of the left ventricular end-diastolic volume (EDV) and end-systolic volume (ESV) measured by 3-dimensional volumetry indexed to body surface area (BSA) were 50.5ml/m2 (25th,75th; 43.4, 56.5) and 20.1ml/m2 (16.3, 21.7) and did not differ by subgroup, p=0.22 and 0.35. The median left ventricular ejection fraction measured by 3-dimensional echocardiography was 60.8% (56.2, 66.1) and did not differ by subgroup (p = 0.43). Diastolic function determined by E/A 1.6 (1.3, 1.9) and E/E' 5.9 (4.9, 6.9) did not differ by treatment group (p = 0.61 and p = 0.83). 3-dimensional left atrial volumes indexed to BSA were measured with an EDV of 13.9 ml/m2 (10.3, 17.1) and an ESV with 27.4 ml/m2 (21.8, 31.5) which did not differ by subgroup (p = 0.95 and p = 0.15, respectively). Median ejection fraction of the LA derived from 3-dimensional volume measurement was 47.6% (40.2, 54.3). It was significantly higher in group 1 in comparison to group 2 53.4% (46.8/59.77) vs. 44.8% (37.93/52.54) (p = 0.028). Longitudinal global strain of the LA also differed between group 1 and 2 with 35% (30.67/39.67) vs. 24% (17/31.08); p=0.0021 with a median of 27% (21, 35) in the total sample.

Conclusion: Patients with idiopathic AF have an unremarkable echo using conventional 2-dimensional echocardiography, but show functional impairment regarding left atrial ejection fraction derived from 3-dimensional volumetry of the LA and longitudinal strain.