Abstract TMP104: Left Atrial Dilatation, Atrial Fibrillation And Stroke, A 5 Year Follow Up Study

Background: Our prior study showed that Atrial Fibrillation (AFib) and not Left Atrial Dilatation (LAD) was associated with ischemic stroke (IS) in a cross-sectional analysis. We sought to validate these findings in a prospective 5-year follow up study. Methods: Patients with transthoracic ECHO (TTE) completed from March-September 2016 were selected. We obtained new diagnoses of Afib and IS over the interval period of 5 years (2016-21). Regression models were used to analyze LAD, Afib and other covariates as they relate to IS, as well as the association of baseline LAD to subsequent AFib. Results: There were 7988 subjects analyzed. Of those we excluded; 578 had IS before 2016 and an additional 249 patients had no follow-up data. Of the remaining 7161, mean age was 65, 54% females, 52% Caucasian, 43% African American, 9% developed new AFib and 3% had a new IS during follow-up. The median follow-up was 47 months. Also, 54% patients had a normal LA, 13% were mildly, 13% were moderately and 20% were severely dilated, of which 6, 11, 13 and 15% were found to have new AFib, respectively (p<0.001). Mild and severe LAD was more likely to experience IS when compared to normal LAD (Model-1:p=0.02 (HR 1.5, 95%CI 1.06-2.3) and p<0.0003 (HR 1.8, 95%CI 1.3-2.5) respectively), and moderate LAD showed a trend (p=0.08). Prior diagnosis of LAD or Afib was associated with a new IS on univariate analysis (Model-2:p<0.0001). However, on multivariate analysis, considering both LAD and Afib in the same model, only Afib remained associated with IS (Model-3: p<0.0001 (HR 1.8, 95%CI 1.3-2.5)) and remained significant even after adjusting for other covariates (Model-4: HR 2.2, 95%CI 1.5-3.3, p=<0.001). Additionally, anticoagulant use was associated with a reduced risk of IS. (HR 0.6, 95%CI 0.4-0.9, P=0.01) Conclusion: LAD increased the probability of AFib discovery during follow-up and was associated with both Afib and IS. However, AFib, not LAD, was independently associated with IS. Medical treatment of AFib was associated with a reduction in future IS, reaffirming the need to identify and treat AFib. Our study suggests the presence of LAD on TTE is a useful marker for identification of high risk individuals for Afib and prospective investigations to identify Afib would provide primary IS prevention.