The Association of Left Atrial Size and Occurrence of Atrial Fibrillation: a Prospective Cohort Study from the Canadian Registry of Atrial Fibrillation

Background: The effect of left atrial (LA) dimension on the recurrence of atrial fibrillation (AF) has been examined in small studies. We evaluated the effect of LA dimension on the occurrence of AF using 2- and 4-year echocardiographic data in a large cohort of patients with new onset AF.

Methods: The Canadian Registry of AF (CARAF) enrolled subjects with AF at the first electrocardiographically confirmed diagnosis. Patients were classified at 2 and 4 years as no recurrent AF (No RAF), paroxysmal AF (PAF), or chronic AF (CAF) based on clinical symptoms and electrocardiographic documentation. The association between baseline, 2-, and 4-year LA dimensions with occurrence of AF as determined by echocardiography was evaluated using a multivariate analysis.

Results: The No RAF group (n = 176) had a significantly smaller LA dimension (36.9 +/- 6.8 mm) at baseline compared to the CAF group (n = 227) (42.8 +/- 7.5 mm, P <.0001). The No RAF and PAF (n = 153) groups did not have a significant change in LA dimension at 2 or 4 years. Only those with CAF had a significant increase in LA dimension at 2 and 4 years, +1.39 mm (95% CI 0.01-2.8) and +3.48 mm (95% CI 1.8-5.2), respectively.

Conclusions: A larger baseline LA dimension is associated with progression to CAF. Patients with no or paroxysmal recurrence had no change in LA dimension over a 4-year period. These findings have implications in tailoring modes of therapy in patients with AF.