To date, the role of CPET (cardiopulmonary exercise testing) for risk stratification in elderly patients with HF (heart failure) with depressed or preserved ventricular function has not been evaluated. In the present study, we analysed whether CPET is useful in predicting outcome in this population. A total of 220 NYHA (New York Heart Association) class I-III patients with HF > or =70 years of age [median age, 75 years; 23% had NYHA class III; and 59% had preserved ventricular systolic function (left ventricular ejection fraction > or =40%)] performed maximal CPET (peak expiratory exchange ratio >1.00). Median peak oxygen uptake was 11.9 ml.kg(-1) of body weight.min(-1), median VE/VCO(2) slope (slope of the minute ventilation/carbon dioxide production ratio) was 33.2 and 45% had an EVR (enhanced ventilatory response) to exercise (VE/VCO(2) slope > or =34). During 19 months of follow-up, 94 patients (43%) met the combined end point of death and hospital admission for worsening HF, arrhythmias or acute coronary syndromes. By Cox multivariable analysis, a creatinine clearance of <50 ml/min {HR (hazard ratio), 1.657 [95% CI (confidence interval), 1.055-2.602]} and EVR [HR, 1.965 (95% CI, 1.195-3.231)] were the best predictors of outcome, while ventricular function had no influence on prognosis. In conclusion, in elderly patients with HF, a steeper VE/VCO(2) slope provides additional information for risk stratification across the spectrum of ventricular function and identifies a high-risk population, commonly not considered in exercise testing guidelines.