A randomized double-blind trial of enalapril in older patients with heart failure and preserved ejection fraction: effects on exercise tolerance and arterial distensibility.

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 AND RESULTS Seventy-one stable elderly (70+/-1 years) patients (80% women) with compensated HFPEF and controlled blood pressure were randomized into a 12-month follow-up double-blind trial of enalapril 20 mg/d versus placebo. Assessments were peak exercise oxygen consumption; 6-minute walk test; Minnesota Living with HF Questionnaire; MRI; Doppler echocardiography; and vascular ultrasound. Compliance by pill count was excellent (94%). Twenty-five patients in the enalapril group versus 34 in the placebo group completed the 12-month follow-up. During follow-up, there was no difference in the primary outcome of peak exercise oxygen consumption (enalapril, 14.5+/-3.2 mL/kg/min; placebo, 14.3+/-3.4 mL/kg/min; P=0.99), or in 6-minute walk distance, aortic distensibility (the primary mechanistic outcome), left ventricle mass, or neurohormonal profile. The effect size of enalapril on peak exercise oxygen consumption was small (0.7%; 95% CI, 4.2% to 5.6%). There was a trend toward improved Minnesota Living with HF Questionnaire total score (P=0.07), a modest reduction in systolic blood pressure at peak exercise (P=0.02), and a marginal improvement in carotid arterial distensibility (P=0.04). CONCLUSIONS In stable, older patients with compensated HFPEF and controlled blood pressure, 12 months of enalapril did not improve exercise capacity or aortic distensibility. These data, combined with those from large clinical event trials, suggest that angiotensin inhibition does not substantially improve key long-term clinical outcomes in this group of patients. This finding contrasts sharply with observations in HF with reduced EF and highlights our incomplete understanding of this important and common disorder.