Summary: Meldonium is a metabolic drug that has attracted growing interest in cardiology in recent years, particularly in the treatment of heart failure (HF) and chronic coronary syndrome (CCS). It modulates cardiomyocyte energy metabolism by inhibiting L-carnitine synthesis, which leads to reduced fatty acid oxidation and a shift in metabolism toward the more energy- -efficient glucose oxidation. This mechanism is particularly important in conditions of hypoxia and ischemia, where optimizing oxygen consumption becomes crucial for myocardial cell survival. This article discusses the physiological basis of cardiac energy metabolism and its disturbances in HF and CCS. It discusses the role of L-carnitine in fatty acid transport and the effect of meldonium on mitochondrial processes. Experimental and clinical data indicate that meldonium can improve cardiac contractile function, increase exercise tolerance, and reduce disease symptoms, while also demonstrating a favorable safety profile. Despite promising results, the use of meldonium remains limited due to the lack of large, randomized clinical trials and regulatory differences. Nevertheless, this drug may represent an important adjunctive therapy for cardiovascular disease.