Obesity is an established risk factor for heart disease; however, it remains unclear how fat deposition in obesity alters the structure and function of the heart in older adults. A new paper published in the European Heart Journal discusses cardiac outcomes in individuals between 60 and 64 years of age following fat accumulation in early or mid-adulthood.
Study: Adulthood adiposity affects cardiac structure and function in later life. Image Credit: Halfpoint / Shutterstock.com
About the study
The current study examines the postulate that adiposity before the target age of 60-64 is associated with long-term negative cardiac outcomes. The study included 1,690 individuals who were part of the National Survey of Health and Development birth cohort, all of whom were White British adults.
All study participants were repeatedly measured for adiposity. Both body mass index (BMI) and waist-to-hip ratio (WHR) values were calculated throughout the study participants' adult lives from the age of 20. Between the ages of 60 and 64, an echocardiographic evaluation of heart structure and function was performed. These parameters included left ventricle (LV) structure/mass, relative wall thickness, internal LV diameter (LVIDd), and function during heart diastole.
Left atrial volume indexed to body surface area (LAVi) was also measured with LV functional characteristics such as the systolic ejection fraction and myocardial contraction fraction (MCF). Together, these measurements were used to clarify the relationships between adiposity and heart structure/function in later life.
What did the results show?
Heart structure
Adults with a higher BMI from age 20 years were associated with a greater risk of increased LV mass (LVM) and LVIDd. LVIDd continued to increase with BMI, irrespective of the current BMI. The increase in LVM with BMI remained consistent at 26, 43, and 53 years of age.
The relative wall thickness (RWT) of the LV increased with BMI after the age of 43 years. This effect was due to the influence of BMI between 60 and 64 years of age.
Systolic function
A higher BMI was associated with poorer systolic heart function in terms of lower ejection fraction at all ages below 60-64 years except 43 years. This association was attributed to BMI at 60-64 years of age.
Similar observations were made for MCF, which declined with increasing BMI from age 20. These effects were also explained by BMI between 60 and 64.
Diastolic function
After compensating for possible confounding factors, the heart's diastolic function decreased with increasing BMI from the age of 20 onwards. This was also attributed to the effect of adiposity or BMI at 60-64 years of age.
LAVi rose with BMI from the age of 26 onwards. Even when BMI at 60-64 was considered, the same associations were observed despite some loss of strength.
A similar trend was also observed for WHR from the age of 43, with MCF declining and LAVi rising with increasing WHR. These associations were observed irrespective of the WHR at 60-64.
Conclusions
The current study presents the results of the longest follow-up period in any birth cohort study in Britain. The study findings identified a link between increased fat deposition, as demonstrated by higher BMI/WHR, in early adult life, followed by deterioration of cardiac structure and impairment of cardiac function.
Older adults with higher fat mass during early adulthood were more likely to have poorer systolic and diastolic function. However, these effects were primarily attributed to excess adiposity at the time of examination rather than earlier in adulthood.
Some of these associations persisted despite subsequent changes in BMI at 60-64 years of age. Persistent changes were observed with LVM, RWT, and LVIDd, thus indicating an enduring influence of adiposity earlier in life.
No evidence suggests a critical window during adult life that determines cardiac outcomes later in life. Importantly, BMI is likely not an ideal measure of body fat mass in young adults due to the presence of increased muscle mass. Moreover, most young adults in the current study had normal BMI values.
Our findings show that excess adiposity over the life course is associated with adverse cardiac structure and function that is only partly attributable to tracking of BMI.”
Primary prevention by targeting the development of obesity and fat deposition in early and mid-adulthood is key to reducing the risk of cardiac damage later in life. In the future, more extensive studies are needed to provide evidence-based frameworks for these strategies and account for dietary intakes with more diverse cohorts.
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