BACKGROUND: The purpose of the current study was to define exercise-induced changes in indices of left ventricular (LV) systolic and diastolic properties in patients with chronic heart failure (HF), compare these changes in patients with HF and a reduced ejection fraction (EF) versus HF and a preserved EF, and compare the hemodynamic responses to activities of daily living with symptom-limited upright exercise. METHODS AND RESULTS: Subjects with HF and a preserved EF (n=8) and subjects with HF and a reduced EF (n=5) underwent symptom-limited Naughton protocol treadmill exercise tests. Implantable hemodynamic monitor data and echocardiographic data were obtained before exercise and at peak exercise. Implantable hemodynamic monitor data were obtained during activities of daily living during a 24-hour time period. In patients with HF and a reduced EF, limited exercise time (639±164 seconds) was associated with a marked rise in right ventricular systolic, diastolic, and estimated pulmonary artery diastolic (ePAD) pressures and an increase in LV end diastolic volume (EDV). LV systolic properties, namely EF, end systolic elastance, stroke work, and preload recruitable stroke work, all decreased. The ePAD/EDV ratio increased; to a large extent, this was dependent on an increase in EDV. By contrast, in HF and a preserved EF, limited exercise time (411±128 seconds) and the marked rise in right ventricular systolic, diastolic, and ePAD pressures were associated with no change in LV EDV. LV systolic properties increased or were unchanged; ePAD/EDV ratio increased during exercise, but the increase was independent of a change in EDV. The ranges of right ventricular systolic, diastolic, and ePAD pressures during activities of daily living were higher than the ranges of these values during the exercise stress test. CONCLUSIONS: Although exercise limitations were similar between HF and a reduced EF and HF and a preserved EF, there were significant differences in exercise-induced changes in LV systolic and diastolic properties. These differences likely reflect the different pathophysiologies of these clinical syndromes of HF.