Relationship between exertional symptoms and functional capacity in patients with heart failure.

OBJECTIVES: The present study was undertaken to investigate the relationship over time between exertional symptoms in heart failure and functional capacity.
BACKGROUND: Most clinicians rely on exertional symptoms rather than on exercise testing to assess functional capacity in heart failure. However, it remains uncertain whether the subjective symptoms reported by patients provide a reliable index of functional capacity.
METHODS: Fifty patients with heart failure underwent serial cardiopulmonary exercise testing and evaluation of exertional fatigue and dyspnea over a period of one to four years. Exercise testing was performed using the Naughton treadmill protocol and a MedGraphics metabolic cart. Fatigue and dyspnea were each scored from 0 to 3 (p = none, 1 = mild, 2 = moderate, 3 = severe). A composite symptom score was determined by adding together the fatigue and dyspnea scores.
RESULTS: Patients underwent a total of 185 tests at an average interval of 4.3 months (average tests/patient = 3.7). Composite symptom scores noted at the time of exercise testing correlated significantly with peak exercise minute oxygen consumption (VO2) (r = 0.47, p < 0.01). In addition, the change in symptoms scores and change in peak VO2 noted between the baseline and final exercise test correlated significantly (r = 0.50, p < 0.01). However, patients reported few or no symptoms (symptom score < or =2) 45% of the time when peak VO2 was <14 ml/min/kg, consistent with a severe functional disability, and 72% of the time when peak VO2 was 14 to 18 ml/min/kg, consistent with moderate functional disability.
CONCLUSIONS: Exertional symptoms reported by patients with heart failure generally correlate with maximal exercise capacity. However, exertional symptoms frequently underestimate the severity of functional disability. Cardiopulmonary exercise testing rather than symptoms should be used to assess functional capacity in heart failure.