Abstract 11610: Differing Risk Factors for Incident Atrial Fibrillation with and without Left Atrial Enlargement
Background Left atrial (LA) enlargement is common in patients with atrial fibrillation (AF), and is associated with an increased risk of embolic complications. However, few studies have assessed whether risk factors differ with regard to the development of AF with and without LA enlargement.
Methods A total of 34722 women enrolled in the Women's Health Study who were >45 years and free of cardiovascular disease and AF at baseline were prospectively followed for incident AF. All AF events were confirmed by medical record review, and echocardiography results performed around the time of AF diagnosis were abstracted from the medical record. LA enlargement was defined as LA diameter >40mm. Cox proportional-hazards models were constructed to assess risk factors for the development of AF with and without increased LA size, respectively. Women with incident AF and normal LA size were censored at the time of AF diagnosis in models assessing AF with LA enlargement and vice versa.
Results During a median follow-up of 15.4 (IQR 14.7-15.8) years, 1011 (3%) women developed AF. Data on LA size were available in 748 (74%) women. Of these, 310 (41%) women developed AF in the presence of LA enlargement, and 438 (59%) women had normal LA size at the time of first AF diagnosis. In multivariable Cox proportional-hazards models, age and height were associated with the development of AF with and without LA enlargement, as shown in the Table. By contrast, hypertension and body mass index were much stronger risk factors for incident AF in the setting of LA enlargement, and diabetes was only associated with AF if the LA was enlarged at the time of first AF occurrence (Table).
Conclusion These data suggest that much of the increased AF risk associated with obesity, hypertension and diabetes may be mediated by and/or dependent on LA enlargement. On the other hand, age and height appear to be able to influence AF risk independent of LA structural remodelling.
- © 2011 by American Heart Association, Inc.