This article focuses on the magnitude of the challenge of heart failure, with particular reference to the disease burden in Spain. The text also deals with the difficulty of estimating the size of the problem, which stems from the fact that heart failure is a common end-point of numerous conditions. The second part of the article presents some reflections on the value of clinical practice guidelines and on the difficulty of incorporating interventions that have proven their efficacy under the controlled conditions of a clinical trial into everyday clinical practice, thereby maximizing their potential benefits. Finally, some suggestions are made on improving both professionals' adherence to clinical practice guidelines and patients' adherence to recommended treatment.