Subclinical Myocardial Damage in Obesity May Be Mitigated by Physical Activity

According to a recent study published in JACC Heart Failure, physical activity is inversely associated with chronic subclinical myocardial damage.¹

Obesity is widely known to be a risk factor for heart failure.² Physical activity has been associated with a lower risk of heart failure in people with obesity, although pathophysiological mechanisms remain unknown.^2,3

Using a non-concurrent cross-sectional prospective design, researchers analyzed the participants in the Atherosclerosis Risk in Community (ARIC) Study⁴ through 4 visits that occurred approximately every 3 years and a fifth follow-up visit that occurred about a decade later.

Assessing for physical activity, obesity status, and high-sensitivity cardiac troponin T (hs-cTnT) levels as a surrogate marker for myocardial damage, subjects were evaluated for physical activity level at visit 3 through a modified Baecke questionnaire later converted into a Metabolic Equivalent of Task (MET) and cross referenced with the American Heart Association (AHA) definitions of physical activity.¹

Measurements of hs-cTnT were drawn at visit 4. Individuals with self-reported cardiovascular disease (CVD), a CVD clinical event, including coronary heart disease, heart failure, or coronary revascularization procedures, and patients with a silent myocardial infarction were excluded from analyses. Individuals with body mass index <18.5 were also excluded from analyses, as were individuals not of black or white race.¹

Of the 9427 individuals included in the analyses, 7.2% had elevated hs-cTnT at visit 4. Of note, the prevalence of elevated hs-cTnT was greater in individuals with lower physical activity levels (7.7% of individuals with poor activity levels vs 6.8% of individuals with the AHA recommended activity levels). After adjusting for CVD mediators in multivariate models, individuals with poor physical activity were more likely to have an elevated hs-cTnT (odds ratio [OR], 1.31; 95% CI, 1.08-1.59; P =.001).¹

In analyses that stratified data by obesity status using the non-obese and recommended activity level group as the reference, individuals with poor physical activity and obesity were the most likely to have elevated hs-cTnT (OR, 2.46; 95% CI, 1.91-3.19; P =.01), while there was a weaker association between individuals with obesity and the recommended activity level with elevated hs-cTnT (OR, 1.68; 95% CI, 1.28-2.21; P <.01).

During a median of 15 years of follow-up, the highest rates of heart failure were seen in the obese and poor activity group (HR, 2.55; 95% CI, 2.14-3.04). Furthermore, within each cross-category of physical activity level and obesity, elevated hs-cTnT was strongly associated with a higher incidence of heart failure (P for interaction <.001) over time.¹

Given the many implications of their results, the researchers noted that “further studies should explore whether hs-cTnT might be used as a marker of cardiovascular health in association with changes in physical activity,” especially people with obesity.¹

Study Limitations

• Self-reported activity levels are likely associated with misclassification and are not entirely representative of the cumulative effects of regular physical activity on myocardial activity.
• Hs-cTnT was measured from stored blood samples and degradation of the samples could have affected the true value of the marker.
• It is difficult to establish the temporality of the observed associations of physical activity with myocardial damage in the study. 

Dr Schrack is a consultant for EMD Serono Research & Development Institute, Inc. Dr Nambi has served as an event adjudicator for a study sponsored by Siemens to evaluate a new high-sensitivity troponin assay. Drs Selvin and Ballantyne have served on an advisory board for Roche Diagnostics. Drs Ballantyne and Nambi, along with Roche and Baylor College of Medicine have filed a provisional patent entitled “Biomarkers to Improve Prediction of Heart Failure Risk.”

References

1. Florido R, Ndumele CE, Kwak L, et al. Physical activity, obesity, and subclinical myocardial damage. JACC Heart Failure. 2017;5(5):377-384. doi:10.1016/j.jchf.2017.02.002
2. Hu G, Jousilahti P, Antikainen R, et al. Joint effects of physical activity, body mass index, waist circumference, and waist-to-hip ratio on the risk of heart failure. Circulation. 2010;121:237-244.
3. Abel ED, Litwin SE, Sweeney G. Cardiac remodeling in obesity. Physiology Review. 2008;88:389-419.
4. The ARIC Investigators. The Atherosclerosis Risk in Communities (ARIC) study: design and objectives. Am J of Epidemiol. 1989;129:687-702.