While exercise intolerance is the primary chronic symptom in elderly patients with heart failure and preserved left ventricular ejection fraction (HFPEF), its pathophysiology and treatment options are not well understood.

The study, which looked at 40 stable, compensated HFPEF outpatients between the ages of 63 and 75 over four months, assessed reduced peak oxygen consumption (VO2), during rest and peak upright cycle exercise. Results found peak VO2 was increased with endurance training, associated with a modest increased peak heart rate (139 vs. 131 beats/minute), but no difference in peak end-diastolic volume, stroke volume, or cardiac output. Estimated peak arterial-venous oxygen difference was significantly increased with endurance training. The effect of this training on cardiac output was responsible for less than 15 percent of the improvement in peak VO2.

"In elderly stable compensated HFPEF patients, peak arterial-venous oxygen difference was higher after [endurance training] and was the primary contributor to improved peak VO2," study authors concluded. "This finding suggests that peripheral mechanisms (improved microvascular and/or skeletal muscle function) contribute to the improved exercise capacity after ET in HFPEF." The authors also suggest that future studies may want to look at the intensity and/or type of exercise training as other means of overcoming exercise intolerance.