Heart failure with preserved ejection fraction (HFpEF) which currently represents approximately 50 % of heart failure (HF) cases is common and associated with high morbidity and mortality. In this review we discuss the emerging HFpEF epidemic focusing on: (1) reasons for the rising prevalence of HFpEF; (2) the abnormalities in cardiac structure and function that dictate the transition from risk factors to HFpEF; (3) novel HFpEF mechanisms that may underlie the increase in HFpEF prevalence; (4) prognosis of HFpEF; and (5) risk prediction in HFpEF. We conclude with AZ-20 10 unanswered questions on HFpEF epidemiology that will be important areas for future investigation. Keywords: Diastolic heart failure Epidemiology Pathophysiology Prognosis Risk estimation Introduction Heart failure with preserved ejection fraction (HFpEF) a common clinical syndrome is a leading cause AZ-20 of morbidity and mortality and currently represents approximately 50 % of heart failure (HF) cases. Understanding the epidemiology of HFpEF continues to be difficult because of problems in HFpEF medical diagnosis as well as the heterogeneous etiologies and pathophysiologies that underlie HFpEF. Even so many high-quality epidemiologic research like the Framingham Center Study as well as the Rochester Epidemiology Task among others possess provided essential understanding into HFpEF on the inhabitants level. These research show that sufferers with HFpEF are mostly elderly much more likely to be feminine than male and also have a higher prevalence of comorbidities such as for example hypertension coronary artery disease (CAD) diabetes mellitus (DM) weight problems anemia persistent kidney disease (CKD) atrial fibrillation and persistent obstructive pulmonary disease [1-3 4 These research have also confirmed that success with HFpEF is certainly poor specifically after hospitalization for HFpEF. Probably the main acquiring from these research and observational registries is usually that HFpEF is an emerging epidemic. The prevalence of HFpEF is usually increasing over time and a populace burden of aging and comorbidities predicts even higher rates of HFpEF in the coming decades. Here we review the current scenery of HF epidemiology focusing on: (1) reasons for the AZ-20 rising prevalence of HFpEF; (2) the abnormalities in cardiac structure and function that dictate the transition from risk factors to HFpEF; (3) novel HFpEF mechanisms that may underlie the increase in HFpEF prevalence; (4) prognosis of HFpEF; and (5) risk prediction in HFpEF. The Changing Scenery of HF Epidemiology HF is the most common cause of hospitalization among individuals above 65 years of age . It affects about 1 % of 40-year-old individuals and its prevalence sharply increases to 10 %10 % in those over 75 years of age [6 7 Overall prevalence of HFpEF AZ-20 has been reported to be 1.1-5.5 % in the general population . However accurate estimation of the prevalence of HFpEF has been challenging due to lack of standardization in the diagnostic criteria and inherent troubles in the diagnosis of HFpEF [9 10 Relative prevalence of HFpEF among all HF patients is usually approximately 50 % although there is usually significant variation (40-71 %) among different studies  likely due to a combination of differing definitions of HFpEF study type (epidemiologic study vs. observational registry) practice setting (inpatient vs. outpatient) and geographic location. An epidemiologic study from Olmstead County Minnesota discovered that the prevalence of HFpEF in accordance with HF with minimal ejection AZ-20 small fraction (HFrEF) is certainly increasing for a price of AZ-20 just one 1 % each year indicating that HFpEF is certainly on track to get the most frequent kind of HF soon . Among sufferers with HF who need hospitalization the percentage of HFpEF in addition has been increasing. Get WITH ALL THE Guidelines-Heart Failing (GWTG-HF) an extremely large nationwide research of HF hospitalization in Ang america (N>110 0 lately showed the fact that proportion of sufferers hospitalized with HF who got HFpEF elevated from 33 percent33 % in 2005 to 39 % this year 2010. Within once interval the percentage of HF hospitalizations because of HFrEF reduced from 52 % to 47 % [11??]. Additionally it is well known the fact that price of rehospitalization in HFpEF is certainly add up to that of HFrEF [3 12 In HFpEF the rehospitalization price was found to become 29 % within 60-90 times of hospital release . Taken jointly these data present the fact that epidemiology of HF is certainly changing which HFpEF is now the predominant type of HF. Body 1.