The association of left atrial size and occurrence of atrial fibrillation: a prospective cohort study from the Canadian Registry of Atrial Fibrillation.

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. (Am Heart J 2004;148:649‐54.) Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia and is responsible for increased morbidity and mortality, particularly in the elderly population. 1,2 The development of paroxysmal and persistent AF is associated with the presence of several factors including age, hypertension, heart failure, mitral valve disease, and increased left atrial (LA) dimension. 3‐ 6 An increase in LA size in the presence of AF has been independently associated with an increased risk of stroke as well as increased mortality. 7,8 Only small studies 9 ‐11 of patients at various stages of AF have prospectively followed LA size over time and its relationship to AF occurrence. The Canadian Registry of Atrial Fibrillation (CARAF) is a noninterventional study of patients following their first electrocardiographic (ECG) diagnosis of AF. Detailed clinical and echocardiographic data were prospectively collected on 899 patients with AF. Our objective was to prospectively evaluate the change in LA size using ECG data over a 4-year period and its effect on the occurrence of AF, independent of other potential causes of atrial enlargement, in patients with a new diagnosis of AF in this large cohort.