The syndrome of heart failure has existed at least as far back as when humans first began to document disease. Clinical texts attributable to Hippocrates describe patients with shortness of breath, edema, and anasarca, in a manner not too varied from contemporary accounts.1 It has also long been realized that heart failure is not caused by a single disease; rather, it is an amalgamate of several diseases that have unique etiologies, natural histories, and treatments.2 The shared feature of this cluster of illnesses is damage to the cardiac tissue. Initially, the heart compensates in various manners to a loss in reserve; however, once there is a critical degree of impairment in its structure and function, a final common pathway emerges that shares similarities in symptoms and findings.
Over the past several decades, dramatic improvements in management of valvular and ischemic heart disease have decreased mortality from these illnesses and consequently led to an increase in the incidence and prevalence of heart failure. This, coupled with the aging of the population, has led to the growth of heart failure prevalence to epidemic proportions. Currently, heart failure affects more than 23 million people globally, of which over five million are Americans.3 Heart failure is a difficult disease to manage and is associated with high rates of morbidity and mortality and high costs, both in terms of direct financial costs as well as indirect cost of patient and caregiver suffering.4 Therefore, it is imperative that we recognize and manage the syndrome using the best currently available information and make concerted efforts to find novel ways to further improve its management.
According to the 2013 American College of Cardiology (ACC)/American Heart Association (AHA) heart failure guidelines:
Heart failure is a complex clinical syndrome that results from any structural or functional impairment of ventricular filling or ejection of blood. The cardinal manifestations of heart failure are dyspnea and fatigue, which may limit exercise tolerance, and fluid retention, which may lead to pulmonary and/or splanchnic congestion and/or peripheral edema. Some patients have exercise intolerance but little evidence of fluid retention, whereas others complain primarily of edema, dyspnea, or fatigue. Because some patients present without signs or symptoms of volume overload, the term “heart failure” is preferred over “congestive heart failure.” There is no single diagnostic test for heart failure because it is largely a clinical diagnosis based on a careful history and physical examination.5
The definition provided by the 2012 European Society of Cardiology (ESC) heart failure guidelines is as follows: “Heart failure can be defined as an abnormality of cardiac structure or function leading to the failure of the heart to deliver oxygen at a rate commensurate with the requirement of the metabolizing tissues, despite normal filling pressures (or only at the expense of increased filling pressures).”6