Abstract 12823: Estimated Cardiorespiratory Fitness and Incident Atrial Fibrillation: The REasons for Geographic And Racial Differences in Stroke (REGARDS) Study

Background: Poor cardiorespiratory fitness (CRF) is an independent predictor of cardiovascular disease (CVD). However, wide utilization of CRF in CVD risk assessment is limited due to its cost, and the need for exercise equipment and skilled personnel. Estimated CRF (e-CRF) based on readily available clinical and self-reported data is a promising alternative though its role as a predictor of incident atrial fibrillation (AF) remains unclear. Methods: This study included 10,126 participants (54.5% women, 35% African American, mean age 63.2 years) from the REasons for Geographic And Racial Differences in Stroke (REGARDS) study who were free of AF at the time of enrollment (2003-2007). Baseline e-CRF was determined using non-exercise algorithms (Table footnote). Incident AF cases were identified at a follow-up examination by electrocardiogram or self-reported medical history. Multivariable logistic regression was used to calculate the odds ratio (ORs) and 95% confidence intervals (CIs) for the association between baseline e-CRF and incident AF. Results: After a median follow-up of 9.4 years, 906 (8.9%) participants developed AF. In a multivariable model adjusted for demographics, baseline CVD risk factors, and potential confounders, each 1-unit increase in e-CRF was associated with a 5% lower risk of AF development (p=0.007). This association remained significant after further adjustment for incident coronary heart disease, heart failure, and stroke, and was stronger in women than men (interaction p-value =0.05). No significant interaction by age, sex, race, history of CVD, or physical limitations was observed. Conclusion: e-CRF using non-exercise algorithms is a useful predictor of incident AF, and the protective effect is more pronounced among women. e-CRF using non-exercise algorithms may serve as a useful alternative to CRF measured by costly and time consuming exercise testing.