Effects of Oral Amino Acid Supplements on Functional Capacity in Patients with Chronic Heart Failure

Amino acids (AAs) availability is reduced in patients with heart failure (HF) leading to abnormalities in cardiac and skeletal muscle metabolism, and eventually to a reduction in functional capacity and quality of life. In this study, we investigate the effects of oral supplementation with essential and semi-essential AAs for three months in patients with stable chronic HF. The primary endpoints were the effects of AA's supplementation on exercise tolerance (evaluated by cardiopulmonary stress test and six minutes walking test (6MWT)), whether the secondary endpoints were change in quality of life (evaluated by Minnesota Living with Heart Failure Questionnaire-MLHFQ) and N-terminal pro-brain natriuretic peptide (NT-proBNP) levels. We enrolled 13 patients with chronic stable HF on optimal therapy, symptomatic in New York Heart Association (NYHA) class II/III, with an ejection fraction (EF) <45%. The mean age was 59 ± 14 years, and 11 (84.6%) patients were male. After three months, peak VO2 (baseline 14.8 ± 3.9 mL/minute/kg vs follow-up 16.8 ± 5.1 mL/minute/kg; P = 0.008) and VO2 at anaerobic threshold improved significantly (baseline 9.0 ± 3.8 mL/minute/kg vs follow-up 12.4 ± 3.9 mL/minute/kg; P = 0.002), as the 6MWT distance (baseline 439.1 ± 64.3 m vs follow-up 474.2 ± 89.0 m; P = 0.006). However, the quality of life did not change significantly (baseline 21 ± 14 vs follow-up 25 ± 13; P = 0.321). A non-significant trend in the reduction of NT-proBNP levels was observed (baseline 1502 ± 1900 ng/L vs follow-up 1040 ± 1345 ng/L; P = 0.052). AAs treatment resulted safe and was well tolerated by all patients. In our study, AAs supplementation in patients with chronic HF improved exercise tolerance but did not change quality of life.