Peak Exercise Oxygen Consumption in Chronic Heart Failure: Toward Efficient Use in the Individual Patient

Abstract

Objectives. This study sought to 1) assess the short-, medium- and long-term prognostic power of peak oxygen consumption (V̇o2) in patients with heart failure; 2) verify the consistency of a nonmeasurable anaerobic threshold (AT) as a criterion of nonapplicability of peak V̇o2; 3) develop simple rules for the efficient use of peak V̇o2in individualized prognostic stratification and clinical decision making.Background. Peak V̇o2, when AT is identified, is among the indicators for heart transplant eligibility. However, in clinical practice the application of defined peak V̇o2cutoff values to all patients could be inappropriate and misleading.Methods. Six hundred fifty-three patients consecutively considered for eligibility for heart transplantation were followed up. Outcomes (cardiac death and urgent transplantation) were determined when all survivors had a minimum of 6 months of follow-up.Results. Contraindication to the exercise test identified very high risk patients. The relatively small sample of women did not allow inferences to be drawn. In men, peak V̇o2stratified into three levels (≤10, 10 to 18 and >18 ml/kg per min) identified groups at high, medium and low risk, respectively. The prognostic power of peak V̇o2≤10 ml/kg per min was maintained even when the AT was not detected. In patients in New York Heart Association functional class III or IV, peak V̇o2did not have prognostic power. In patients in functional class I or II, peak V̇o2stratification was prognostically valuable, but less so at 6 than at 12 or 24 months. Age did not influence peak V̇o2prognostic stratification.Conclusions. A contraindication to exercise testing should be considered a priority for listing patients for heart transplantation. Only in less symptomatic male patients does a peak V̇o2≤10 ml/kg per min identify short-, medium- and long-term high risk groups. A peak V̇o2>18 ml/kg per min implies good prognosis with medical therapy.