Background: A reduced level of daily activities is thought to be an important determinant of aerobic exercise intolerance in patients with chronic heart failure chronic heart failure; however, few data exist about the relationship between habitual physical activity level and peak aerobic capacity in patients at different clinical stages of left ventricular dysfunction.
Study objectives: The purposes of this study were as follow: (1) to validate a simple interviewer-administered scoring system for evaluation of habitual physical activity level of patients with chronic heart failure and asymptomatic left ventricular dysfunction (ALVD); (2) to determine the relationship between habitual physical activity level and peak aerobic capacity in chronic heart failure and ALVD patients; and (3) to compare habitual activity levels among different New York Heart Association (NYHA) classes in these populations.
Setting: Cardiology division at a tertiary-care hospital.
Study population: We studied 167 consecutive patients with chronic heart failure (NYHA class I to III), 40 patients with ALVD, and 52 healthy subjects (HS).
Measurements and results: Habitual physical activity level was evaluated by means of an interview-based activity scoring system considering leisure time and occupational activities and also recent deconditioning events (eg, hospital admissions); a final activity score (AS) ranging from 0.8 to 5 was obtained. All patients and HS performed a symptom-limited cardiopulmonary exercise test up to a respiratory exchange ratio of > or = 1.1. AS was an independent predictor of peak oxygen consumption (VO(2)) in all groups, with a significantly higher VO(2) vs AS relationship slope in the ALVD and HS groups than in the chronic heart failure group. Moreover, AS was found to be significantly lower in chronic heart failure than in ALVD patients and HS (1.6 +/- 0.6 vs 2.2 +/- 0.7 vs 3.5 +/- 1.1, respectively; p < 0.0001), as was peak VO(2) (14.7 +/- 3.7 mL/kg/min vs 20 +/- 4 mL/kg/min vs 33.1 +/- 10 mL/kg/min, respectively; p < 0.0001), but the latter differences were canceled after adjusting for AS values. Significant AS and peak VO(2) reductions were observed in chronic heart failure patients with NYHA class progression from I to III.
Conclusions: Habitual physical activity level is progressively decreased with worsening of heart failure symptoms and is related to peak aerobic capacity in both chronic heart failure and ALVD patients. However, this relationship appears to be weak in patients with chronic heart failure, whereas daily activity is a strong independent predictor of peak aerobic capacity both in ALVD patients and HS. This may be related to the intervention of factors other than skeletal muscle deconditioning in the exercise pathophysiology of chronic heart failure patients.