Background: Cardiorespiratory fitness is a strong predictor of all-cause mortality in cardiac patients, but its assessment requires maximal exercise testing which is costly and impractical in most settings. We developed a sub-maximal protocol to predict VO2peak by a moderate perceptually-regulated one-km treadmill walk (1KTWT).The aim of this study is to examine the association of the exercise capacity by 1KTWT with all-cause mortality in a cohort of patients with stable cardiac disease. Methods: 1016 male outpatients, aged 38-83 years, underwent 1KTWT and were followed up for a median of 73 months. Subjects were stratified according to quartiles of predicted VO2peak (ml/kg/min) and walking speed (km/h). Cox proportional hazard regression ratio (HR) and the area under the receiver-operating-curve (AUC) were calculated. Results: There were a total of 103 deaths during the follow-up period resulting in an average annual mortality of 1.6%. Risk of all-cause mortality was inversely related to both predicted VO2peak and walking speed. Predicted VO2peak quartiles ranged 9-19 ml/kg/min, 20-22 ml/kg/min, 23-25 ml/kg/min, 25-40 ml/kg/min. Walking speed quartiles ranged 3.0-3.6 km/h, 3.7-4.0 km/h, 4.1-4.7 km/h, 4.8-7.7 km/h. After adjustment for age, medical history, ejection fraction and medication, the HRs for mortality were 0.91, 0.71 and 0.21 for the fourth, third and second VO2peak quartiles, with the first quartile as the referent (P for trend <0.0001). Similarly, the HRs for mortality were 0.83, 0.40 and 0.26 for the fourth, third and second walking speed quartiles, with the first quartile as the referent (P for trend <0.001). The AUC were similar for walking speed for predicted VO2peak (0.69 vs 0.68). Conclusion: Estimated VO2peak and walking speed during 1KTWT are independent predictors of all-cause mortality in stable cardiac patients. The 1KTWT represents a low cost and simple tool for the indirect evaluation of cardiorespiratory fitness in an outpatient setting.
A moderate perceptually-regulated one-km treadmill walk predicts mortality among men with stable cardiac disease.
MAZZONI, Gianni;GRAZZI, Giovanni
2012
Abstract
Background: Cardiorespiratory fitness is a strong predictor of all-cause mortality in cardiac patients, but its assessment requires maximal exercise testing which is costly and impractical in most settings. We developed a sub-maximal protocol to predict VO2peak by a moderate perceptually-regulated one-km treadmill walk (1KTWT).The aim of this study is to examine the association of the exercise capacity by 1KTWT with all-cause mortality in a cohort of patients with stable cardiac disease. Methods: 1016 male outpatients, aged 38-83 years, underwent 1KTWT and were followed up for a median of 73 months. Subjects were stratified according to quartiles of predicted VO2peak (ml/kg/min) and walking speed (km/h). Cox proportional hazard regression ratio (HR) and the area under the receiver-operating-curve (AUC) were calculated. Results: There were a total of 103 deaths during the follow-up period resulting in an average annual mortality of 1.6%. Risk of all-cause mortality was inversely related to both predicted VO2peak and walking speed. Predicted VO2peak quartiles ranged 9-19 ml/kg/min, 20-22 ml/kg/min, 23-25 ml/kg/min, 25-40 ml/kg/min. Walking speed quartiles ranged 3.0-3.6 km/h, 3.7-4.0 km/h, 4.1-4.7 km/h, 4.8-7.7 km/h. After adjustment for age, medical history, ejection fraction and medication, the HRs for mortality were 0.91, 0.71 and 0.21 for the fourth, third and second VO2peak quartiles, with the first quartile as the referent (P for trend <0.0001). Similarly, the HRs for mortality were 0.83, 0.40 and 0.26 for the fourth, third and second walking speed quartiles, with the first quartile as the referent (P for trend <0.001). The AUC were similar for walking speed for predicted VO2peak (0.69 vs 0.68). Conclusion: Estimated VO2peak and walking speed during 1KTWT are independent predictors of all-cause mortality in stable cardiac patients. The 1KTWT represents a low cost and simple tool for the indirect evaluation of cardiorespiratory fitness in an outpatient setting.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
