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Published on: April 19, 2019
Mid-Life Cardiorespiratory Fitness, Obesity, and Risk of Atrial Fibrillation: The Cooper Center Longitudinal Study
Ambarish Pandey1, Benjamin Willis1, Carolyn E Barlow1
1Division of Cardiology, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, Texas, USA; Research Division, The Cooper Institute, Dallas, Texas, USA.
Insights
Higher body mass index (BMI) in midlife independently increases atrial fibrillation (AF) risk. Lower cardiorespiratory fitness (CRF) also elevates AF risk, but this association is mainly explained by BMI.
Area of Science:
- Cardiology
- Preventive Medicine
- Epidemiology
Background:
- Lower cardiorespiratory fitness (CRF) and higher body mass index (BMI) are linked to increased risk of myocardial infarction and heart failure.
- The independent contribution of CRF and BMI to atrial fibrillation (AF) risk is not well-established.
Purpose of the Study:
- To evaluate the association between midlife CRF, BMI, and the risk of AF in older age.
Main Methods:
- 18,493 participants without AF underwent midlife assessment of CRF and BMI.
- Proportional hazards models were used to assess the association between midlife CRF, BMI, and AF risk, adjusting for confounders.
- Changes in CRF and BMI were also assessed in a subset of participants.
Main Results:
- Higher midlife BMI was significantly associated with increased AF risk, independent of CRF (HR per 1-kg/m²: 1.05).
- Lower midlife CRF was associated with higher AF risk (HR per 1 MET: 0.98), but this became non-significant after adjusting for BMI.
- Changes in CRF during follow-up were not associated with AF risk.
Conclusions:
- The link between low fitness and AF risk was primarily driven by BMI.
- Obesity in midlife is independently associated with an increased risk of developing AF later in life.
Background:
Lower cardiorespiratory fitness (CRF) and higher body mass index (BMI) are associated with a higher risk of myocardial infarction and heart failure. However, the independent contribution of these lifestyle factors to the risk of atrial fibrillation (AF) is less well established.
Objectives:
The purpose of this study was to evaluation the association between midlife CRF, BMI, and risk of AF in older age.
Methods:
This study included 18,493 participants without AF who underwent assessment of CRF (estimated using the maximal treadmill time) and BMI in middle age and had Medicare coverage after the age of 65 years. The association among midlife CRF, BMI, and risk of AF was assessed by fitting a proportional hazards intensity model to the failure time data with adjustment for potential confounders. The association between changes in CRF and BMI in middle age and the risk of AF was also assessed in the subset of participants with repeat CRF assessments.
Results:
Among 18,493 participants (79% men), a higher midlife BMI was significantly associated with a higher risk of AF independent of CRF levels and other potential confounders (hazard ratio per 1-kg/m2: 1.05; 95% confidence interval: 1.03-1.06). Lower midlife CRF was also associated with higher risk of AF (hazard ratio per 1 MET higher CRF: 0.98; 95% confidence interval: 0.96-0.99). However, this association was attenuated and not significant after further adjustment for BMI. Change in CRF on follow-up was also not associated with the risk of AF after adjustment for other confounders.
Conclusions:
The association between low fitness and AF was primarily driven by differences in BMI. In contrast, obesity was independently associated with excess AF risk.
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