Background: Quantitative data on the frequency with which transition from intermittent to permanent atrial fibrillation occurs are lacking. We conducted this study to determine the proportion of patients with intermittent atrial fibrillation who progress to permanent atrial fibrillation and to investigate baseline clinical characteristics that might predict such a progression.
Methods: This retrospective cohort study included 231 patients who were seen with intermittent atrial fibrillation at a university hospital-based clinic from January 1978 through December 1997. Patients' medical records and electrocardiograms were reviewed and data were collected for all clinic visits through May 1998. The proportion of patients who remained free of transition from intermittent to permanent atrial fibrillation was calculated by the Kaplan-Meier method. A Cox proportional hazards model was used to determine the effect of some baseline characteristics on this transition.
Results: The number of patients who remained free of transition from intermittent to permanent atrial fibrillation was 92% (95% confidence interval 88%-96%) at 1 year and 82% (95% confidence interval 75%-88%) at 4 years. Among 5 baseline characteristics (age, sex, structural heart disease, atrial fibrillation at presentation, and use of an antiarrhythmic medicine before presentation), the 2 significant predictors of progression from intermittent to permanent atrial fibrillation were age (P =.0003) and being in atrial fibrillation at presentation (P =.0006). The hazard ratio associated with 10 years of advancing age was 1.82 (95% confidence interval 1.31-2.51), and the hazard ratio associated with atrial fibrillation at presentation was 3.56 (95% confidence interval 1.73-7.34).
Conclusions: Approximately 18% of patients who had intermittent atrial fibrillation were permanently in atrial fibrillation after 4 years of follow-up. Age and being in atrial fibrillation at presentation were the only 2 important clinical variables identified in predicting such a progression.