Some 40%-50% of patients with heart failure present with a normal ejection fraction. Today, it is thought that this clinical syndrome is caused by diastolic dysfunction. However, the concept is still controversial because echocardiographic assessment is difficult and misdiagnosis is frequent. Although the epidemiological characteristics of these patients have been shown to differ from those of patients with systolic heart failure, both clinical features and prognosis are similar: medium-term mortality is elevated due to the high prevalence of comorbid conditions and no randomized clinical trial has identified an effective therapy able to change the natural history of this disease. In addition, a significant increase in all-cause mortality has even been observed in patients with asymptomatic diastolic dysfunction, a condition which occurs frequently in the general population.