Introduction: Atrial Fibrillation (AF) is the most common serious cardiac arrhythmia and is associated with an increased risk of stroke and mortality. These risks can be modified with oral anticoagulation therapy. Clinically, the arrhythmia can be permanent or intermittent. Prior studies that have used time-constant, categorical covariates to examine the relationship between the pattern of AF and the occurrence of adverse events have produced conflicting results. We hypothesized that the amount of time that patients spend in AF, hereinafter termed arrhythmia “burden”, may be important in predicting adverse events.
Objective: To examine the effects of the burden of AF on all-cause mortality.
Methods: The Manitoba Follow-Up Study is a longitudinal, prospective study of 3983 originally healthy young men (mean age at entry 30 years) who have been followed with routine medical and electrocardiographic examinations since 1948. After 60 years of follow-up to July 1, 2008, AF had been documented on the electrocardiograms of 581 men (15% of the cohort) and 3182 (80%) of the original cohort had died. We created a Cox proportional hazards model with time-dependent covariates to estimate relative risks for mortality according to AF burden. AF status during each follow-up visit was classified as persistent when the patient was in AF on consecutive examinations, transient when the patient reverted to sinus rhythm after being in AF and incident when the patient developed AF after a period in sinus rhythm.
Results: Results of the Cox proportional hazards regression model are displayed in the Table. Age, persistent AF and incident AF were all significant variables in the model. Holding all the other variables constant, persistent AF increased the risk of death by two times and incident AF increased the risk of death by 87%.
Conclusions: Persistent AF and incident AF are associated with increased all-cause mortality. Estimating AF burden may have implications for risk stratification in patients with AF.