Carnitine Paradox in Patients With Heart Failure

Carnitine, a nutrient contained in the red meat, plays an important role in the energy metabolism in the heart and skeletal muscles through transferring fatty acid into the mitochondria. It is also associated with the suppression of fibrosis in the myocardium via arachidonic acid metabolism. Although carnitine is a key nutrient in the heart, recent study also showed that carnitine generated trimethylamine N-oxide from gut microbiota, which promote accelerated coronary artery atherosclerosis and increases the risk of HF. In contrast, carnitine insufficiency is common in patients with HF because of poor oral intake, malabsorption, loss of skeletal muscle as principal storage of the carnitine, and carnitine transporter abnormality. We previously reported that carnitine insufficiency was associated with the reduced left ventricular diastolic function, physical functional decline, and increased cardiac events in patients with HF with preserved ejection fraction. Thus, in patients with stage A or B of HF, it may be reasonable to abstain carnitine from the red meat. But, in patients with stage C or D of cachexic HF, abstaining red meat may lead to increase the risk of carnitine insufficiency, resulting in the worsening of HF; we postulate such phenomenon as “carnitine paradox”. These results suggest that carnitine supplementation is a potential theraputic option in cachexic HF patients.