Relationship of age and exercise performance in patients with heart failure: the HF-ACTION study

Abstract

Background: More than three fourths of patients with heart failure (HF) are 65 years and older, and older age is associated with worse symptoms and prognoses than is younger age. Reduced exercise capacity is a chief HF complaint and indicates poorer prognosis, especially among elderly persons, but the mechanisms underlying functional decline in older patients with HF are largely unknown.

Methods: Baseline cardiopulmonary exercise testing data from the HF-ACTION trial were assessed to clarify age effects on peak oxygen consumption (VO(2)) and ventilation-carbon dioxide production (VE/VCO(2)) slope.

Results: Among 2,331 New York Heart Association class II-IV patients with HF, increased age corresponded to decreased peak VO(2) (-0.14 mL kg(-1) min(-1) per year >40 years; P < .0001) and increased VE/VCO(2) slope (0.30 U/y >70 years; P < .0001). In a multivariable model with 34 other potential determinants, age was the strongest independent predictor of peak VO(2) (partial R(2) 0.130, total R(2) 0.392; P < .001) and a significant but relatively weaker predictor of VE/VCO(2) slope (partial R(2) 0.037, total R(2) 0.199; P < .001). Blunted peak heart rate was also a strong predictor of peak VO(2). Although peak heart rate and age were strongly correlated, both were significant independent predictors of peak VO(2) when analyzed simultaneously in a model. Aggregate comorbidity increased significantly with age but did not account for age effects on peak VO(2).

Conclusions: Age is the strongest predictor of peak VO(2) and a significant predictor of VE/VCO(2) slope in the HF-ACTION population. Age-dependent comorbidities do not explain changes in peak VO(2). Age-related changes in cardiovascular physiology, potentially magnified by the HF disease state, should be considered a contributor to the pathophysiology and a target for more effective therapy in older patients with HF.

Figure 1. Peak VO₂, peak heart rate (HR), O₂ pulse and ventilatory efficiency (VE/VCO₂) in relation to age in the HF-ACTION subject population

In each plot individual data points represent actual data and regression lines of best fit are shown for some variables. a) Peak VO₂ (mL/kg/min) is displayed as a function of age. The regression line of best fit demonstrates a spline at approximately age 40 where the individual best fit regression lines have characteristics: <40 years: coefficient +0.03, partial r² = 0.00, p=0.494; >40 years: coefficient −0.14, partial r² = 0.12; p<0.0001 (Table 4). b) Peak exercise HR (beats per minute) is displayed as a function of age. The best fit regression line is shown and displays an inverse relationship to age across the age distribution. c) Peak O₂ pulse (mL/kg/heart beat) is displayed as a function of age. There is a statistically significant but small correlation (r = −0.04, p = 0.03) between the two variables. d) VE/VCO₂ slope is displayed as a function of age. The regression line of best fit demonstrates a spline at approximately age 70 where the individual best fit regression lines have characteristics: <70 years: coefficient +0.11, partial r² = 0.014, p<0.0001; >70 years: coefficient +0.30, partial r² = 0.011; p<0.0001 (Table 5).

Figure 1. Peak VO₂, peak heart rate (HR), O₂ pulse and ventilatory efficiency (VE/VCO₂) in relation to age in the HF-ACTION subject population

In each plot individual data points represent actual data and regression lines of best fit are shown for some variables. a) Peak VO₂ (mL/kg/min) is displayed as a function of age. The regression line of best fit demonstrates a spline at approximately age 40 where the individual best fit regression lines have characteristics: <40 years: coefficient +0.03, partial r² = 0.00, p=0.494; >40 years: coefficient −0.14, partial r² = 0.12; p<0.0001 (Table 4). b) Peak exercise HR (beats per minute) is displayed as a function of age. The best fit regression line is shown and displays an inverse relationship to age across the age distribution. c) Peak O₂ pulse (mL/kg/heart beat) is displayed as a function of age. There is a statistically significant but small correlation (r = −0.04, p = 0.03) between the two variables. d) VE/VCO₂ slope is displayed as a function of age. The regression line of best fit demonstrates a spline at approximately age 70 where the individual best fit regression lines have characteristics: <70 years: coefficient +0.11, partial r² = 0.014, p<0.0001; >70 years: coefficient +0.30, partial r² = 0.011; p<0.0001 (Table 5).

Figure 1. Peak VO₂, peak heart rate (HR), O₂ pulse and ventilatory efficiency (VE/VCO₂) in relation to age in the HF-ACTION subject population

In each plot individual data points represent actual data and regression lines of best fit are shown for some variables. a) Peak VO₂ (mL/kg/min) is displayed as a function of age. The regression line of best fit demonstrates a spline at approximately age 40 where the individual best fit regression lines have characteristics: <40 years: coefficient +0.03, partial r² = 0.00, p=0.494; >40 years: coefficient −0.14, partial r² = 0.12; p<0.0001 (Table 4). b) Peak exercise HR (beats per minute) is displayed as a function of age. The best fit regression line is shown and displays an inverse relationship to age across the age distribution. c) Peak O₂ pulse (mL/kg/heart beat) is displayed as a function of age. There is a statistically significant but small correlation (r = −0.04, p = 0.03) between the two variables. d) VE/VCO₂ slope is displayed as a function of age. The regression line of best fit demonstrates a spline at approximately age 70 where the individual best fit regression lines have characteristics: <70 years: coefficient +0.11, partial r² = 0.014, p<0.0001; >70 years: coefficient +0.30, partial r² = 0.011; p<0.0001 (Table 5).

Figure 1. Peak VO₂, peak heart rate (HR), O₂ pulse and ventilatory efficiency (VE/VCO₂) in relation to age in the HF-ACTION subject population

In each plot individual data points represent actual data and regression lines of best fit are shown for some variables. a) Peak VO₂ (mL/kg/min) is displayed as a function of age. The regression line of best fit demonstrates a spline at approximately age 40 where the individual best fit regression lines have characteristics: <40 years: coefficient +0.03, partial r² = 0.00, p=0.494; >40 years: coefficient −0.14, partial r² = 0.12; p<0.0001 (Table 4). b) Peak exercise HR (beats per minute) is displayed as a function of age. The best fit regression line is shown and displays an inverse relationship to age across the age distribution. c) Peak O₂ pulse (mL/kg/heart beat) is displayed as a function of age. There is a statistically significant but small correlation (r = −0.04, p = 0.03) between the two variables. d) VE/VCO₂ slope is displayed as a function of age. The regression line of best fit demonstrates a spline at approximately age 70 where the individual best fit regression lines have characteristics: <70 years: coefficient +0.11, partial r² = 0.014, p<0.0001; >70 years: coefficient +0.30, partial r² = 0.011; p<0.0001 (Table 5).