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 capa city. BACKGROUND Most clinicians rely on exertional symptoms rather than on exerc ise testing to assess functional capacity in heart failure. However, it rem ains 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 pe riod of one to four years. Exercise testing was performed using the Naughto n 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 a nd 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 mi nute 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 f inal exercise test correlated significantly (r = 0.50, p < 0.01). However, patients reported few or no symptoms (symptom score less than or equal to 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/m in/kg, consistent with moderate functional disability. CONCLUSIONS Exertional symptoms reported by patients with heart failure gen erally correlate with maximal exercise capacity. However, exertional sympto ms frequently underestimate the severity of functional disability. Cardiopu lmonary exercise testing rather than symptoms should be used to assess func tional capacity in heart failure. (C) 1999 by the American College of Cardi ology.