The ability of a submaximal exercise test to predict maximal exercise capacity in patients with heart failure.

We investigated the ability of a submaximal exercise test to predict the maximal aerobic potential and hence exercise capacity of patients with chronic heart failure. Heart rate, oxygen consumption and carbon dioxide production were measured continuously during treadmill exercise in 29 patients with chronic heart failure (NYHA Class II-III). The anaerobic threshold was determined as the oxygen consumption at which carbon dioxide production increased non-linearly relative to oxygen consumption. Maximal oxygen consumption could not be predicted from the heart rate response to submaximal exercise. Oxygen consumption at the anaerobic threshold (28 patients) and at a respiratory quotient of 1 (23 patients) did predict maximal oxygen consumption (r = 0.93, r = 0.88, respectively). Measurement of oxygen consumption during submaximal exercise can be used to assess maximal exercise capacity in patients with heart failure.