Definition	Heart failure occurs when abnormality of cardiac function causes failure of the heart to pump blood at a rate sufficient for metabolic requirements, or maintains cardiac output only with a raised filling pressure. It is characterized clinically by breathlessness, effort intolerance, fluid retention, and poor survival. It can be caused by systolic or diastolic dysfunction and is associated with neurohormonal changes.1 Left ventricular systolic dysfunction (LVSD) is defined as a left ventricular ejection fraction (LVEF) below 0.40. It can be symptomatic or asymptomatic. Defining and diagnosing diastolic heart failure can be difficult. Recently proposed criteria include: (1) clinical evidence of heart failure; (2) normal or mildly abnormal left ventricular systolic function; and (3) evidence of abnormal left ventricular relaxation, filling, diastolic distensibility, or diastolic stiffness.2 The clinical utility of these criteria is limited by difficulty in standardizing assessment of the last criterion.7
Incidence/Prevalence	The incidence and prevalence of heart failure increase with age. In those younger than 65 years, the incidence is one per 1,000 men a year and 0.4 per 1,000 women a year. In those older than 65 years, incidence is 11 per 1,000 men a year and five per 1,000 women a year. In those younger than 65 years, the prevalence of heart failure is one per 1,000 men and one per 1,000 women; in those older than 65 years, the prevalence is 40 per 1,000 men and 30 per 1,000 women.3 The prevalence of asymptomatic LVSD is 3 percent in the general population.4,5,6 The mean age of people with asymptomatic LVSD is lower than that for symptomatic individuals. Heart failure and asymptomatic LVSD are more common in men.4,5,6 The prevalence of diastolic heart failure in the community is unknown. The prevalence of heart failure with preserved systolic function in people in the hospital with clinical heart failure varies from 13 to 74 percent.7,8 Less than 15 percent of people younger than 65 years with heart failure have normal systolic function, whereas the prevalence is about 40 percent in people older than 65 years.7
Etiology/Risk Factors	Coronary artery disease is the most common cause of heart failure.3 Other common causes include hypertension and idiopathic dilated congestive cardiomyopathy. After adjustment for hypertension, the presence of left ventricular hypertrophy remains a risk factor for the development of heart failure. Other risk factors include cigarette smoking, hyperlipidemia, and diabetes mellitus.4 The common causes of left ventricular diastolic dysfunction are coronary artery disease and systemic hypertension. Other causes are hypertrophic cardiomyopathy, restrictive or infiltrative cardiomyopathies, and valvular heart disease.8
Prognosis	The prognosis of heart failure is poor, with five-year mortality ranging from 26 to 75 percent.3 Up to 16 percent of people are readmitted with heart failure within six months of first admission. In the United States, it is the leading cause of hospital admission among people older than 65 years.3 In people with heart failure, a new myocardial infarction increases the risk of death (relative risk: 7.8; 95 percent confidence interval [CI]: 6.9 to 8.8); 34 percent of all deaths in people with heart failure are preceded by a major ischemic event.9 Sudden death, mainly caused by ventricular arrhythmias, is responsible for 25 to 50 percent of all deaths, and is the most common cause of death in people with heart failure.10 The presence of asymptomatic LVSD increases an individual's risk of having a cardiovascular event. One large prevention trial found that, for a 5 percent reduction in ejection fraction, the risk ratio for mortality was 1.20 (95 percent CI: 1.13 to 1.29), for hospital admission for heart failure it was 1.28 (95 percent CI: 1.18 to 1.38), and for development of heart failure it was 1.20 (95 percent CI: 1.13 to 1.26).4 The annual mortality of patients with diastolic heart failure varies in observational studies (1.3 to 17.5 percent).7 Reasons for this variation include age, the presence of coronary artery disease, and variation in the partition value used to define abnormal ventricular systolic function. The annual mortality for left ventricular diastolic dysfunction is lower than that found in patients with systolic dysfunction.11
Clinical Aims	To relieve symptoms; to improve quality of life; to reduce morbidity and mortality with minimum adverse effects.
Clinical Outcomes	Functional capacity (assessed by the New York Heart Association [NYHA] functional classification or, more objectively, by using standardized exercise testing or the six-minute walk test)12; quality of life (assessed with questionnaires)13; mortality; adverse effects of treatment. Proxy measures of clinical outcome (e.g., LVEF, hospital readmission rates) are used here only when clinical outcomes are unavailable.