BACKGROUND: Exercise intolerance is the primary symptom in older patients with heart failure and preserved ejection fraction (HFPEF), however little is known regarding its mechanisms and therapy.

METHODS: 71 elderly stable, compensated HFPEF patients (age 70+1 years; 80% women) with controlled blood pressure were randomized into a 12 month follow-up (FU) double-blind trial of enalapril 20 mg per day (E) vs. placebo (P). Assessments included: peak exercise oxygen consumption (VO2); six-minute walk test; Minnesota Living with HF Questionnaire (MLHF); MRI; Doppler-echocardiography; and vascular ultrasound.

Inclusion Criteria:

• All participants will be 60 years of age or older.

Exclusion Criteria:

1. systolic dysfunction
2. patients with evidence of significant ischemic or valvular heart disease
3. chronic pulmonary disease.

Participants who appear preliminarily eligible are invited to a formal screening visiting with an investigator cardiology physician. They also undergoing a rest and exercise electrocardiogram and echocardiogram and pulmonary function testing as well as blood hematology and chemistry tests.

Final eligibility will be based upon all information available at the conclusion of the screening visits test, including hospital and outpatient records, history, physical examination, echocardiogram and exercise test.