In Reply We appreciate the thoughtful response to our work from Dr Aengevaeren and colleagues. We agree that the relationship between coronary artery calcium score and objective measures of cardiorespiratory fitness is complex and requires further investigation. Studies from the extremes of exercise suggest that coronary artery calcium (CAC) scores may actually be higher in such individuals.1 In addition, as Puri and coauthors2 point out, statin therapy is linked to increased CAC with the association frequently attributed to plaque stabilization. However, the hypothesis that CAC presence or extent may reduce cardiovascular events implies causality and conflicts with a wealth of data suggesting that CAC reflects burden of atherosclerotic disease and may be used as a secondary measure to identify high-risk individuals for statin therapy. As Criqui and coauthors3 point out, the density of calcification may better reflect plaque characteristics not captured by the CAC score. Of note, in both fully adjusted and age-, race-, and sex-adjusted linear regression models for calcium density in CARDIA, we did not find associations between baseline fitness and calcium density at year 25.4 Nevertheless, improved methods to quantify morphology and quantity of subclinical coronary artery disease remain relevant to the study of cardiovascular and metabolic diseases.
Shah RV, Murthy VL, Lima JAC. Fitness and Coronary Artery Calcification—Reply. JAMA Intern Med. 2016;176(5):716-717. doi:10.1001/jamainternmed.2016.0901