Usefulness of plasma branched-chain amino acid analysis in predicting outcomes of patients with nonischemic dilated cardiomyopathy

Abstract

The metabolism of branched-chain amino acids (BCAAs) is reported to change in heart failure (HF) and correlate with cardiac function. However, the effect of BCAAs on HF remains controversial. We investigate the prognostic value of the plasma BCAA level in nonischemic dilated cardiomyopathy (NIDCM). This study enrolled 39 NIDCM patients, who underwent plasma amino acid (AA) analysis. The ratio of BCAAs to total AAs was calculated. All patients were divided into two groups at the median of BCAA/total AA ratio; high BCAA/total AA group (≥0.15, n = 20) and low BCAA/total AA group (< 0.15, n = 19). A cardiac event was defined as a composite of cardiac death, hospitalization for worsening HF, and lethal arrhythmia. The mean age was 51.1 ± 12.3 years and left ventricular ejection fraction (LVEF) was 32.7 ± 10.1%. In the low BCAA/total AA group, the body mass index and the total cholesterol level were lower than in the high BCAA/total AA group. The BCAA/total AA ratio was positively correlated with LVEF (r = 0.35, P = 0.031) and negatively correlated with brain natriuretic peptide (r = −0.37, P = 0.020). The low BCAA/total AA group had a lower cardiac event-free rate (5-year: 100% versus 73%; P = 0.019). In univariate analysis, angiotensin converting enzyme inhibitor or angiotensin II receptor blocker (hazard ratio: 0.045, P = 0.0014), hemoglobin (hazard ratio: 0.49 per 1 g/dL, P = 0.0022), and BCAA/total AA ratio < 0.15 (hazard ratio: not available, P = 0.0066) were major predictors for cardiac events. The BCAA/total AA ratio might be a useful predictor for future cardiac events in patients with NIDCM.