Methods: Patients with post-infarction heart failure (45-87 yrs, 22-males, 5-females, all received b-blockers and ACE-inhibitors, EF 29%, peak oxygen uptake 13 ml/kg/min) were randomized to 12-weeks, 2-3 times per week, of either moderate exercise-intensity (70% of peak heart rate), high-intensity interval-training (95% of peak heart rate) or to a control group that received advise from their regular doctors. Patients in the two exercise-groups covered similar distance on the treadmill at each exercise-session so that only exercise-intensity differed; i.e. the duration of exercise was longer in the moderate-intensity group. Ultrasound was used to assess LV-dimension and function (including Tissue Doppler Imaging, TDI) and endothelial function in the brachial-artery.