**1. Introduction**

The mortality, hospitalization, and prevalence rates of heart failure (HF) are increasing, in spite of decrease in coronary artery and cerebrovascular disease mortality.[1] Importantly, heart failure with normal ejection fraction (HFNEF) currently accounts for more than 50% of all heart failure patients and as the prevalence of HFNEF in the heart failure population rises by 1% a year.[2]

Approximately half of patients with a diagnosis of heart failure have a normal left ventricular (LV) ejection fraction (EF) without valve disease which is defined as diastolic heart failure (DHF), because it is attributed to LV diastolic dysfunction.[3] The prevalence of DHF increase even more dramatically with age more than HF with a reduced EF and is much more common in women than in men at any age. Studies examining prevalence of diastolic heart failure in hospitalized patients or in patients undergoing outpatient diagnostic screening and prospective community based studies have shown that the prevalence of diastolic heart failure approaches 50%.[4-6] Although HF patients with preserved systolic function has a slightly better prognosis than HF patients with abnormal systolic function, there is a fourfold higher mortality risk compared with subjects free of HF.[7]
