Heart Failure

Heart failure (HF) is a condition in which the heart is unable to pump blood to adequately supply the body's metabolic needs. It affects approximately 5 million people in the US, and more than half a million new cases are diagnosed per year.^1,2 In 2003, more than 57,000 people died of HF, and it was an underlying or contributing cause of death in approximately 287,000.² The most common causes of HF are⁸⁴:

• CAD
• Hypertension
• Valvular heart disease

The risk for HF increases as people age,² and HF is the leading cause of hospitalization for patients aged 65 years and older.⁸⁵ At age 40, the lifetime risk of HF is⁸⁶:

• 1 in 5 for both men and women overall
• 50% higher for women (1 in 6) than for men (1 in 9) without antecedent MI

Click on the links below for more information:

• HF in Women
• HF Diagnostic Issues
• Measuring Endogenous BNP for HF Diagnosis

HF in Women

HF is common among women with CAD.⁸⁷ Approximately 46% of women who have an MI will be disabled with HF within 6 years (compared with 22% of men).⁸⁸

The HERS and HERS II* studies identified 9 risk factors that were independently associated with the development of HF in women with established CAD⁸⁷:

• Diabetes
• Atrial fibrillation
• Myocardial infarction
• Renal insufficiency
• Hypertension
• Obesity
• Current smoking
• Left bundle-branch block
• Left-ventricular hypertrophy

_{*HERS = Heart and Estrogen/progestin Replacement Study.}

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HF Diagnostic Issues

Early diagnosis is essential for successfully treating the underlying causes, but initial diagnosis of HF can be difficult.⁸⁴ False diagnoses are common.^89,90 Diagnosis may be even more difficult in women than in men.^89,90 In 1 study, out of 78 patients with a false-positive diagnosis, 73% were women.⁹⁰

A systematic approach has been recommended to improve diagnostic accuracy for HF:

• Complete clinical history to assess for signs/symptoms and risk factors of HF.^84,91
• Thorough physical examination, including cardiovascular, venous, pulmonary, hepatic, and extremity assessments.^84,91 Assessment of the patient's ability to perform routine/desired activities.⁹¹ Exercise intolerance is inextricably linked to the diagnosis of HF.⁹²
• Laboratory workup for various disease markers, such as B-type natriuretic peptide (BNP), electrolytes, blood count/lipids, urinalysis, hemoglobin, and thyroid, renal, and hepatic function.^84,91,93
• Diagnostic testing.^84,91,93
• Electrocardiography, chest radiography, and echocardiography are the primary recommended diagnostic tests for the initial assessment of HF.^84,91,93
• Noninvasive stress imaging (eg, nuclear imaging or echocardiography) should be considered for patients with known CAD or a high probability of CAD and no angina (except those who are not candidates for revascularization).^84,91,93
• Reduced exercise capacity is a clinical hallmark of HF, likely the result of dyspnea and fatigue—the primary symptoms of HF.^91,92,94

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Measuring Endogenous BNP for Diagnosing Heart Failure

• Measuring BNP is a useful tool to help establish or exclude a diagnosis of HF in the emergency department (ED).^95-97
• A BNP level <100 pg/mL has a high negative predictive value of ≥90%.^95,96
• A BNP level >500 pg/mL has a high positive predictive value (87%).⁹⁶
• Many patients at this level require hospitalization.⁹⁵
• In patients with a BNP level in the mid range (ie, 100-500 pg/mL), considering patient history of HF and clinical variables—ie, history of CAD, lower extremity edema, pulmonary edema, cephalization of the pulmonary arteries, and cardiomegaly—can help make a diagnosis.⁹⁶
• A history of HF in patients in the mid range makes the diagnosis of HF more probable (likelihood ratio [LR] of 4.3).
• Presence of 2 of the variables above in patients in the mid range is strongly indicative of HF (LR of 3.3), even in the absence of a positive history.
• Positive history and the presence of 2 variables in patients in the mid range has an LR (10.2) similar to that of a level >500 pg/mL (8.1).

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