A practical guide to heart-failure diagnosis
This illustration shows enlargement of the ventricular cavity during heart failure.
Heart failure (HF) is the fastest-growing clinical cardiac disorder in the United States. Presently, the epidemiologic impact of HF is staggering: An estimated 5.7 million Americans are living with HF with nearly 700,000 new cases diagnosed each year.1 As such, HF represents a serious health threat and places a very noticeable strain on the health-care system. In 2010 alone, HF will cost the United States an estimated $39.2 billion, which includes the cost of health services, medications, and loss of productivity.1 As life expectancy improves and other cause mortality is reduced, HF will likely continue to grow in prominence.
Although common, HF is frequently misdiagnosed, particularly in primary-care settings where symptom presentation is usually less acute than in the hospital.2 Approximately one in five people who have HF die within one year of diagnosis,1 suggesting further that patients are being diagnosed late into disease progression. Additionally, up to 50% of persons with HF may be asymptomatic. A major factor in improving mortality and quality of life is early recognition of symptoms. Primary-care providers need to be able to recognize the warning signs of HF and must be equipped with the knowledge necessary to make an early diagnosis.
Background and etiology
HF is a complex clinical syndrome characterized by impaired myocardial performance. This is typically manifested as the heart's inability to properly fill with or eject blood. HF can be caused by a number of structural or functional cardiac abnormalities.
The causes of HF can be separated into two broad categories.
Underlying causes generally consist of either congenital or acquired cardiac structural abnormalities. These abnormalities may affect the coronary arteries, heart valves, pericardium, or myocardium. In the United States as well as other industrialized nations, ischemic heart disease is the most common condition leading to HF, causing approximately 75% of cases.3 Other chronic conditions that contribute to cardiac structural abnormalities that fall into this category include diabetes and hypertension.
Precipitating causes make up the second category. It is particularly important to identify those causes of HF that may be reversible. Often, a patient with an underlying cause (e.g., coronary artery disease [CAD]) may develop the first clinical manifestations of HF through a precipitating factor (e.g., a bacterial or viral infection or a tachyarrhythmia). Such other precipitating causes as physical, dietary, fluid, or emotional excesses can hasten decompensation in patients with chronic HF. Such high-output states as thyrotoxicosis, pregnancy, and profound anemia can precipitate acute HF anemia in patients with no known underlying structural cardiac abnormalities. Additionally, drug overdose—either recreational (cocaine, alcohol) or prescription (calcium channel blockers, beta blockers)—can precipitate HF.
History and physical examination
A complete history and physical exam are the first steps in diagnosing HF and any underlying or precipitating causes. The clinical presentation of HF, however, is highly variable. Physical signs vary greatly depending on the chronicity of the condition and degree of compensation and chamber involvement (right ventricle vs. left ventricle vs. both ventricles).
However, patients with HF typically present in one of three ways: (1) with a syndrome of decreased exercise tolerance, (2) with a syndrome of fluid retention, or (3) with no symptoms or symptoms of another cardiac or noncardiac disorder.4