Associations Between Acylcarnitine to Free Carnitine Ratio and Adverse Prognosis in Heart Failure Patients with Reduced or Preserved Ejection Fraction

AIMS: The failing heart is accompanied by disturbed energy metabolism with mitochondrial dysfunction. Carnitine transports fatty acids into mitochondria for β-oxidation. Decreased myocardial carnitine levels accompanied by increased plasma carnitine levels in heart failure (HF) have been reported. The plasma acylcarnitine to free carnitine ratio (AC/FC) is recognized as a marker of carnitine deficiency. We aimed to investigate the impact of the AC/FC on HF prognosis, taking into consideration differences between HF patients with preserved ejection fraction (HFpEF) and those with reduced ejection fraction (HFrEF). METHODS AND RESULTS: Consecutive 168 HF patients were divided into three groups based on their AC/FC: first to third tertiles (n = 56, respectively). We followed up all patients for cardiac events including cardiac death and/or worsening HF. During the follow-up period (1004 days), there were 23 cardiac deaths and 28 worsening HF. In the Kaplan-Meier analysis, the cardiac event rate of the third group was highest among the three groups (P = 0.022). In the Cox proportional hazard analysis, AC/FC was a predictor of cardiac events (P = 0.007). When HFpEF (n = 79) and HFrEF (n = 89) were analysed separately, the cardiac event rate of the third group was highest with regard to HFpEF (P = 0.008), but not HFrEF (P = 0.321). In the Cox proportional hazard analysis, AC/FC was a predictor of cardiac events with regard to HFpEF (P = 0.031), but not HFrEF (P = 0.095). Therefore, the impact of the AC/FC on cardiac events was different between HFpEF and HFrEF (P = 0.042 for interaction). CONCLUSIONS: The AC/FC can identify high risk HF patients, especially in HFpEF.