Abstract Heart failure is a systemic and multiorgan syndrome with metabolic failure as a fundamental mechanism. As a consequence of its impaired metabolism, other processes are activated in the failing heart, further exacerbating the progression of heart failure. Recent evidence suggests that modulating cardiac energy metabolism by reducing fatty acid oxidation and/or increasing glucose oxidation represents a promising approach to the treatment of patients with heart failure. Clinical trials have demonstrated that the adjunct of trimetazidine to the conventional medical therapy improves symptoms, cardiac function and prognosis in patients with heart failure without exerting negative hemodynamic effects. This review focuses on the rationale and clinical benefits of trimetazidine by acting on cardiac metabolism in heart failure, and aims to draw attention to the readiness of this agent to be included in all the major guidelines dealing with heart failure.