Chronic heart failure is a severe clinical syndrome among the most remarkable for prevalence and morbidity in the developed western countries. The European STREP project HEARTFAID aims at realizing an innovative platform of services which will improve the processes of diagnosis, prognosis and therapy provision in the heart failure domain. The core of the platform intelligence is a Clinical Decision Support System, designed by integrating innovative knowledge representation techniques and hybrid reasoning methods, and including advanced tools for the analysis of diagnostic data. In this paper we discuss how we are using semantic web technologies for implementing a real, significant clinical scenario, covering the clinical course of a heart failure patient.