EPIDEMIOLOGY OF ACUTE HEART FAILURE
Currently, the prevalence of heart failure (HF) in the United States is approaching 6 million, a number that will continue to grow as the population ages.1 Despite advances in pharmacologic and device therapies, HF results in significant mortality and morbidity, including frequent emergency department visits and hospitalizations for decompensation. Acute heart failure (AHF) accounts for an estimated 700,000 emergency department visits2 and over 1 million hospitalizations annually in the United States.1 It is the leading cause of hospitalization in patients over 65 years of age, a population expected to grow considerably over the next 20 years.1 Highlighting the prevalence of comorbid conditions in the HF population, an additional 3 million hospitalizations occur annually in which HF is listed as a secondary diagnosis.3 In a large, community-based study, the incidence of AHF was as high as 11.6 cases per 1000 patients per year in those over the age of 55 years.4 The economic impact of the HF epidemic is profound, and costs attributable to inpatient care are estimated to exceed 30 billion dollars annually.5
Data from large registries reveals that the typical AHF patient is > 70 years old, white (~80%), and equally likely to be female (~50%) compared to male.6,7 Although most AHF patients are white, in the community setting, black males have the highest incidence of decompensation (15.7 per 1000 people per year), followed by black women (13.3 per 1000 people per year), white men (12.3 per 1000 people per year), and white women (9.9 per 1000 people per year).4
Although historically attention has focused on patients with systolic dysfunction (HF with reduced ejection fraction [HFrEF]), it is now clear that over 50% of AHF admissions occur in those with preserved ejection fraction (HF with preserved ejection fraction [HFpEF]).8 Additionally, the proportion of hospitalizations in those with HFpEF is increasing considerably compared to those with HFrEF, likely a reflection of the aging population.9 Several differences exist between these two groups, with HFpEF patients being more likely to be older and female, more likely to have less clinical coronary artery disease (CAD), and more likely to have atrial fibrillation, chronic kidney disease, higher blood pressure, and chronic pulmonary disease compared to their HFrEF counterparts.9 Importantly, HFpEF patients with AHF have greater hospital lengths of stay and are more likely to be discharged to a skilled nursing facility.9
Importance of Comorbidities
Comorbidities are common in patients presenting with AHF, including systemic hypertension (> 70%),10 CAD (57%),2 diabetes mellitus (40%),7 renal dysfunction (30%-67%),11 anemia (50%-70%),12 atrial fibrillation (31%),7 and chronic obstructive pulmonary disease (COPD; 30%),10 among others. These comorbidities are associated with higher inpatient mortality, regardless of the presence of preserved or reduced ejection fraction.13,14 They may also confound ...