Left atrial dilatation: A cohort analysis with strong implications for future atrial fibrillation and stroke monitoring

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Introduction: Atrial fibrillation (AF) increases the risk of thromboembolism five-fold. Left atrial dilatation (LAD) is a known predictor of AF. It is necessary to better understand the association of LAD, AF and stroke to determine if screening with cardiac monitoring as a prevention measure for stroke is potentially warranted in patients with LAD and no history of cryptogenic stroke. Aim: To evaluate the high risk association of LAD on routine echocardiography with AF and stroke. Methods: A retrospective review of all patients with an echocardiogram performed within Henry Ford Health System from Mar 6th to Sept 6th 2016 was conducted. Patients were categorized based on the degree of LAD (mild, moderate and severe). Chisquared tests and two-sample t-tests were used to compare characteristics and multivariate logistic regression analyses were done with AF and stroke as outcomes in two separate models adjusting for the exposure variables. Results: From a total of 8679 patients, 54% were female and 41% were African American. The mean age was 64.9 years (SD=16.9). Patients were divided into normal LA size (55%), mild LAD (15%), moderate LAD (12%) and severe LAD (18%). Patients with any LAD were older (70.7±15.0 vs 60.1±17.0 p<0.001), had higher prevalence of AF (36% vs 11% p<0.001), stroke (21% vs 16%, p<0.001) and CHADS2Vasc scores (2.9 ± 1.9 vs 4.0± 1.9 p<0.001). In multivariate analysis, AF was more common in any LAD compared to normal (OR 2.51 CI 2.15-2.93 p<0.001). The odds of AF increased significantly with LAD severity (Mild 1.8, Moderate 2.0 and Severe 3.7). There was no significant association between LAD and stroke in the multivariate analyses (OR 0.97 CI 0.85-1.11, p=0.69). Female gender (OR 0.60, p<0.001) and African American race (OR 0.54, p<0.001) were protective against AF, although not against stroke which was increased in African Americans (OR 1.42, p<0.001). Conclusion: Left atrial dilatation is commonly found on routine echocardiography and AF is established in only one-third of those patients. Structural LAD represents a significant marker for AF, although many patients with LAD are yet to be diagnosed with AF. Left atrial dilatation is an attractive high risk marker for occult AF that may warrant prolonged cardiac monitoring for primary identification of AF.





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