The relationships among the skeletal muscle mass index, cardiorespiratory fitness and the prevalence of coronary artery disease in the elderly population

Objective: Few studies have investigated the association between cardiorespiratory fitness (CRF) impairment and coronary artery disease (CAD) and the mediating mechanism. Therefore, we investigated the impact of skeletal muscle mass (SMM) on the relationship between CRF and coronary artery disease (CAD) in elderly people. Methods: In this cross-sectional study, 109 elderly patients with coronary artery stenosis >= 50% were included in the CAD group, and 148 patients with coronary artery stenosis < 50% were included as controls. Mediation analyses were performed to determine the role of the skeletal muscle index (SMI) in the relationship between CRF and the prevalence of CAD. A receiver operating characteristic (ROC) curve analysis was used to evaluate the predictive value of CRF markers and the SMI. Results: The oxygen pulse, VO2 max, and MET max were significantly associated with the SMI. In the multiple logistic regression analyses, the oxygen pulse and SMI were both independently correlated with the prevalence of CAD. The mediation analyses showed that the SMI affects the relationship between CRF markers (oxygen pulse, VO2 max, and MET max) and the prevalence of CAD. The receiver operating characteristic (ROC) curve analysis showed that when CRF and the SMI are considered together, the predictive power for CAD is stronger than that of the CRF alone. Conclusion: Enhancing CRF can facilitate improvement in SMM and decrease the prevalence of CAD in the elderly population. The addition of the SMI to CRF markers may increase the predictive value of CAD.