Joint Associations Between Cardiorespiratory Fitness, Adiposity, and Mortality in Cardiac Outpatients Within a Secondary Prevention Program

Purpose: Both cardiorespiratory fitness (CRF) and obesity have been well-established as predictors of cardiometabolic risk and mortality. This study sought to investigate the joint association of CRF and adiposity measures with all-cause and cardiovascular (CVD) mortality in a cohort of patients with stable CVD. Methods: Data were extracted from the ITER registry. The sample was composed of 2860 cardiac patients involved in an exercise-based secondary prevention program between 1997 and 2023. Patient CRF was estimated using the 1-km treadmill walking test, and measures of body mass index (BMI) and predicted body fat percentage (pBF%) were determined. Cox proportional hazard models were used to determine associations with mortality. All results were adjusted for demographic and clinical confounders. Results: A total of 1034 deaths (463 of CVD) occurred over a median of 11 years. Each of the fitness-fatness combinations was associated with an increased risk of mortality as compared with normal weight-fit or low pBF%-fit groups. As regards BMI, compared to the reference group, higher mortality risks were observed for overweight-unfit (HR = 1.93: 95% CI, 1.55-2.41; P < .0001), and obese-unfit patients (HR = 1.63: 95% CI, 1.28-2.08; P < .0001). Similar magnitudes were detected in the moderate pBF%-unfit (HR = 2.47: 95% CI, 1.99-3.06) and high pBF%-unfit (HR = 2.07: 95% CI, 1.69-2.54; P < .0001) groups. A similar pattern was observed for CVD mortality. Conclusion: While overweight and obesity have been associated with an increased risk of death, maintaining CRF can mitigate this risk. These findings support the fundamental role of CRF in exercise assessment and prescription in secondary prevention programs.