High-Level Physical Activity, Coronary Artery Calcium, and Mortality
Is there an association between high levels of physical activity, clinically significant coronary artery calcification (CAC), and subsequent mortality risk?
The Cooper Center Longitudinal Study is a prospective observational study of patients from the Cooper Clinic in Dallas, TX, a preventive medicine facility. The present study included participants seen from January 13, 1998, through December 30, 2013, with mortality follow-up through December 31, 2014. A total of 21,758 generally healthy men without prevalent cardiovascular disease (CVD) were included if they reported their physical activity level and underwent CAC scanning. Self-reported physical activity was categorized as ≥3,000 (n = 1,561); 1,500 to 2,999 (n = 3,750); and <1,500 (n = 16,447) metabolic equivalent of task (MET)-minutes/week (min/wk). CAC scores were categorized into ≥100 (n = 5,314) and <100 (n = 16,444) Agatston units (AU). All-cause and CVD mortality were determined using the National Death Index Plus.
Among the 21,758 male participants, baseline (mean ± standard deviation) age was 51.7 ± 8.4 years. Men with ≥3,000 MET-min/wk were more likely to have prevalent CAC of ≥100 AU (relative risk, 1.11; 95% confidence interval [CI], 1.03-1.20) compared to those with less physical activity. In the group with physical activity of ≥3,000 MET-min/wk and CAC ≥100 AU, the CAC level was 807 ± 1,120 AU. After a follow-up duration of 10.4 ± 4.3 years, 759 all-cause and 180 CVD deaths occurred, including 40 all-cause and 10 CVD deaths among those with physical activity ≥3,000 MET-min/wk. Men with CAC <100 AU and physical activity ≥3,000 MET-min/wk were about half as likely to die compared with men with <1,500 MET-min/wk (hazard ratio [HR], 0.52; 95% CI, 0.29-0.91). In the group with CAC ≥100 AU, men with ≥3,000 MET-min/wk did not have a significant increase in all-cause mortality (HR, 0.77; 95% CI, 0.52-1.15) when compared to men with physical activity <1,500 MET-min/wk. In the least active men, those with CAC ≥100 AU were twice as likely to die of CVD compared with those with CAC <100 AU (HR, 1.93; 95% CI, 1.34-2.78).
This study suggests that high levels of physical activity (≥3,000 MET-min/wk) are associated with prevalent CAC but are not associated with increased all-cause or CVD mortality after a decade of follow-up, even in the presence of clinically significant CAC levels.
There is a known association between high-level physical activity and CAC, and there is a known association in the general population between CAC and CV risk. However, the clinical significance of increased coronary artery calcium in an athletic population is not known, and data from the general population have been used to raise concern that coronary calcium among endurance athletes is a harbinger of CV risk. Data from this study suggest otherwise. Specifically, although higher levels of habitual physical activity were associated with increased coronary artery calcium, a) mortality risk was lower among more active individuals, and b) the presence of increased coronary calcium among more active individuals did not portend increased mortality risk. It is possible that physical activity leads to more stable coronary calcification (without an increased risk of morbid and mortal CV events), or that other beneficial effects of exercise simply outweigh any increased risk associated with CAC. Sedentary behavior and physical inactivity are associated with substantial health risks, and physical activity mitigates those risks. Data from this study support that higher levels of physical activity are not associated with higher mortality risk, regardless of CAC.
Keywords: Athletes, Calcification, Physiologic, Calcinosis, Coronary Artery Disease, Diagnostic Imaging, Exercise, Metabolic Equivalent, Metabolic Syndrome X, Plaque, Atherosclerotic, Primary Prevention, Risk, Sedentary Lifestyle, Sports
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