Abstract
The epidemiology of atrial fibrillation (AF) without comorbidities, known as 'lone AF', is uncertain. Although it has been considered a benign condition, we hypothesized that it confers a worse prognosis compared with a matched sample without AF. We described the proportion of AF without comorbidities (clinical, subclinical cardiovascular disease and triggers) among the entire AF sample in Framingham Heart Study (FHS). We compared AF without comorbidities with typical AF, and age-, sex- and cohort-matched individuals without AF, using Cox proportional hazards analysis in relation to combined cardiovascular events (stroke, heart failure, myocardial infarction), and mortality. Of 10,311 FHS participants, 1,961 were diagnosed with incident AF, among which 173 individuals had AF without comorbidities (47% women, mean age 71±12 years). AF without comorbidities had a prevalence of 1.7% of the entire cohort, and an annual incidence of 0.5 per 1000 person-years. During a median follow-up of 9.7 years after initial AF, 137 individuals with AF without comorbidities (79.2%) died and 141 individuals developed cardiovascular events (81.5%). AF without comorbidities had significantly lower mortality (HR 0.67, 95%CI 0.55-0.81, P < .001) and total cardiovascular events (HR 0.66, 95% CI 0.55-0.80, P < .001) compared with typical AF. However, mortality (HR1.43, 95% CI 1.18-1.75, P < .001) and risk of total cardiovascular events (HR 1.73, 95% CI 1.39-2.16, P < .001) were higher than age-, sex-, and cohort-matched individuals without AF. The risk of cardiovascular outcomes and mortality among individuals with AF without comorbidities is lower than typical AF, but is significantly elevated compared with matched individuals without AF.
Highlights
The epidemiology of atrial fibrillation (AF) without comorbidities, known as ‘lone AF’, is uncertain. it has been considered a benign condition, we hypothesized that it confers a worse prognosis compared with a matched sample without AF
We described the proportion of AF without comorbidities among the entire AF sample in Framingham Heart Study (FHS)
AF without comorbidities had a prevalence of 1.7% of the entire cohort, and an annual incidence of 0.5 per 1000 person-years
Summary
We described the proportion of AF without comorbidities (clinical, subclinical cardiovascular disease and triggers) among the entire AF sample in Framingham Heart Study (FHS). We compared AF without comorbidities with typical AF, and age-, sex- and cohort-matched individuals without AF, using Cox proportional hazards analysis in relation to combined cardiovascular events (stroke, heart failure, myocardial infarction), and mortality. The Framingham Heart Study was initiated in 1948 to examine cardiovascular disease and its risk factors. The study enrolled community-dwelling individuals, termed the Original cohort (N = 5209), who underwent examinations every 2 years.[8] In 1971, the study enrolled the Original cohort’s children and their spouses into the Offspring cohort (n = 5124), who had examinations approximately every 4 or 8 years.[9] During each Heart Study visit, a research physician and technicians collected data for cardiovascular risk factors and interim cardiovascular events. The Boston University Medical Center Institutional Review Board approved the study protocols at each examination cycle
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