Heart failure (HF) is a clinical syndrome that occurs in patients who, because of an inherited or acquired abnormality of cardiac structure and/or function, develop a constellation of clinical symptoms (dyspnea and fatigue) and signs (edema and rales) that lead to frequent hospitalizations, a poor quality of life, and a shortened life expectancy.
HF is a burgeoning problem worldwide, with more than 20 million people affected. The overall prevalence of HF in the adult population in developed countries is 2%. HF prevalence follows an exponential pattern, rising with age, and affects 6–10% of people over age 65. Although the relative incidence of HF is lower in women than in men, women constitute at least one-half the cases of HF because of their longer life expectancy. In North America and Europe, the lifetime risk of developing HF is approximately one in five for a 40-year-old. The overall prevalence of HF is thought to be increasing, in part because current therapies for cardiac disorders, such as myocardial infarction (MI), valvular heart disease, and arrhythmias, are allowing patients to survive longer. Very little is known about the prevalence or risk of developing HF in emerging nations because of the lack of population-based studies in those countries. Although HF once was thought to arise primarily in the setting of a depressed left ventricular (LV) ejection fraction (EF), epidemiologic studies have shown that approximately one-half of patients who develop HF have a normal or preserved EF (EF ≥40–50%). Accordingly, HF patients are now broadly categorized into one of two groups: (1) HF with a depressed EF (commonly referred to as systolic failure) or (2) HF with a preserved EF (commonly referred to as diastolic failure).
As shown in Table 234-1, any condition that leads to an alteration in LV structure or function can predispose a patient to developing HF. Although the etiology of HF in patients with a preserved EF differs from that of patients with depressed EF, there is considerable overlap between the etiologies of these two conditions. In industrialized countries, coronary artery disease (CAD) has become the predominant cause in men and women and is responsible for 60–75% of cases of HF. Hypertension contributes to the development of HF in 75% of patients, including most patients with CAD. Both CAD and hypertension interact to augment the risk of HF, as does diabetes mellitus.
Table 234-1 Etiologies of Heart Failure |Favorite Table|Download (.pdf)
Table 234-1 Etiologies of Heart Failure
|Depressed Ejection Fraction (<40%)|
|Coronary artery disease||Nonischemic dilated cardiomyopathy|
|Myocardial infarctiona||Familial/genetic disorders|
|Myocardial ischemiaa||Infiltrative disordersa|
|Chronic pressure overload||Toxic/drug-induced damage|
|Obstructive valvular diseasea||Viral|
|Chronic volume overload||Chagas' disease|
|Regurgitant valvular disease||Disorders of rate and rhythm|
|Intracardiac (left-to-right) shunting||Chronic bradyarrhythmias|