Exercise intolerance.

Patients with heart failure and normal EF have severe chronic exercise intolerance. The pathophysiology of exercise intolerance in this syndrome is incompletely understood, but as in systolic heart failure, it is likely multifactorial. Current data suggest that important contributors include decreased LV diastolic compliance, decreased aortic distensibility, exaggerated exercise systolic blood pressure, relative chronotropic incompetence, and possibly anemia and skeletal muscle remodeling. Because it is a primary determinant of quality of life, can be quantified objectively, is reproducible, and is modifiable, exercise intolerance is an attractive therapeutic target.