The prognostic value of functional capacity in patients with mild to moderate heart failure

Thirty patients with ischemic (n = 14) or idiopathic dilated (n = 16) cardiomyopathy were followed long-term to determine the prognostic value of measuring entry exercise capacity. At the time of referral for management of symptomatic heart failure, studies included radionuclide angiography, M-mode echocardiography, 24-hour Holter and graded exercise testing with measured oxygen peak consumption (peak VO2). Inclusion criteria were NYHA class II (n = 16) or III (n = 14) despite at least 3 months of treatment with digitalis and diuretics, left ventricular ejection fraction less than 50%, left ventricular end-diastolic diameter (LVEDD) greater than 50 mm, and exercise capacity limited by dyspnea or fatigue. Patients were treated with diuretics (100%), digitalis (83%), and vasodilators (60%) and were followed for at least 6 months (mean 15). The 1-, 2- and 3-year cumulative survival rates were 75.4%, 70.2%, and 70.2%, respectively. Univariate predictors of survival included measured peak VO2 (p = 0.0026), as well as age, estimated peak VO2 (based on exercise time), presence of left bundle branch block, LVEDD, and frequency of ventricular arrhythmias. Multivariate analysis revealed that measured peak VO2 was the single best independent predictor of survival (p less than 0.001). We conclude that assessment of functional capacity provides useful independent prognostic information in patients with mild to moderate heart failure.