Heart failure (HF) is common, costly, disabling and lethal, and can be prevented. The progression of overt HF (CHF) can be slowed by correct management including precise diagnosis and appropriate therapy. Patients with CHF can be misdiagnosed, mainly in primary care, where patients are actually less symptomatic than those seen in hospitals. Accurate diagnosis requires objective evidence of cardiac dysfunction at rest by imaging techniques, according to the European Society of Cardiology (ESC) Guidelines. The EPICA Project (EPidemiologia da Insuficiência Cardiaca e Aprendizagem) was one of the first European studies designed to evaluate the prevalence of CHF according to those criteria. The estimated overall prevalence of CHF in Portugal was 4.36% in adults over 25 years. 1058 individuals were identified by the Boston questionnaire as possible or probable CHF cases; only 551 had objective evidence of cardiac dysfunction at rest by echocardiography. 264 patients in sinus rhythm had a Boston score > 3 and no echocardiographic abnormalities. These patients were predominantly older obese women; coronary artery disease was less prevalent than in patients with proved CHF. The ECG was normal in 40.9%, versus 20% in CHF patients. About one half of these patients were prescribed ACE inhibitors and diuretics; 17% were prescribed digoxin. According to these EPICA data concerning CHF, older obese women are more frequently misdiagnosed and incorrectly medicated.