Aims: The objectives of this study were to determine the long-term outcome and the predictors of adverse events in patients originally diagnosed with lone atrial fibrillation (AF).
Methods and results: This population-based historical cohort study comprised 46 residents of Olmsted County, MN, USA, with well-documented, clinically defined lone AF and a complete two-dimensional echocardiographic examination. The original echocardiographic videotape recordings were analysed in a blinded fashion for left atrial volume (LAV) and left ventricular ejection fraction. With 1296 person-years of follow-up, the median duration of AF was 27 (first quartile=24, third quartile=33) years. Twenty-three (50%) patients developed events. Cerebral infarction occurred in seven patients, myocardial infarction in 11, and congestive heart failure in 16. In a multivariable analysis, patients with indexed LAV >or=32 mL/m(2) had a significantly worse event-free survival (adjusted HR, 4.46; 95% CI, 1.56-12.74; P=0.005). All cerebral infarctions occurred in patients with an indexed LAV >32 mL/m(2).
Conclusion: Patients originally diagnosed with benign lone AF follow divergent courses based on LAV. Those originally diagnosed with lone AF and normal sized atria had a benign clinical course throughout the long-term follow-up. Patients with increased LAV at diagnosis or later during the follow-up experienced adverse events.