Additional value of left atrial appendage geometry and hemodynamics when considering anticoagulation strategy in patients with atrial fibrillation with low CHA₂DS₂-VASc scores

Background Strokes occur in some patients with atrial fibrillation (AF), even when the CHA₂DS₂-VASc (congestive heart failure, hypertension, age >75 years, diabetes mellitus, prior stroke or transient ischemic attack, vascular disease, age>65 years, female sex) score is low. Objective We sought to determine the factors defining the residual stroke risk in patients with AF and low CHA₂DS₂-VASc scores, with a particular focus on the hemodynamics and geometry of the left atrial appendage (LAA). Methods From February 1, 2008 to December 31, 2012, 66 consecutive patients with nonvalvular AF and a CHA₂DS₂-VASc score of 0 or 1 (except a point for the female sex) were enrolled. All patients were admitted with a diagnosis of acute ischemic stroke. The control group consisted of patients with nonvalvular AF without a history of stroke. Results The LAA orifice area was larger (4.35 ± 1.51 cm² vs 2.83 ± 0.9 cm²; P <.001) and the LAA flow velocity was lower (41.9 ± 22.7 cm/s vs 54.4 ± 19.9 cm/s; P <.001) in the stroke group than in the control group. Low LAA flow velocity (<40 cm/s) and large LAA orifice area (>4 cm²) were independent predictors of stroke. Patients with an LAA flow velocity of <40 cm/s and an LAA orifice of >4.0 cm² had a markedly higher odds ratio (odds ratio 10.9; 95% confidence interval 3.0–40.0; P <.001) of stroke than did those with preserved LAA flow velocity and smaller LAA orifice. Conclusion Even in patients with low CHA₂DS₂-VASc scores, the presence of both decreased LAA flow velocity and increased LAA orifice size was associated with a high odds ratio of stroke. Future large prospective studies are needed to assess whether these patients should receive anticoagulants.