Table 28-3 and 28-4, taken from the European Society of Cardiology heart failure guideline, recommend a routine assessment to establish the diagnosis and likely cause of heart failure. Once the diagnosis of heart failure has been made, the first step in evaluating heart failure is to determine the severity and type of cardiac dysfunction, by measuring ejection fraction through two-dimensional echocardiography and/or radionuclide ventriculography. Measurement of ejection fraction is the gold standard for differentiating between the two forms of heart failure, systolic and diastolic, and is particularly important given that the approaches to therapy for each syndrome differ somewhat. The history and physical examination should include assessment of symptoms, functional capacity, and fluid retention.
Functional capacity is measured through history taking or preferably an exercise test. Analysis of expired air during exercise offers a precise measure of the patient’s physical limitations. However, this test is uncommonly performed outside of cardiac transplant centers. The NYHA has classified heart failure into four functional classes that may be determined by history taking. The NYHA functional classification should not be confused with the stages of heart failure described in the American College of Cardiology/American Heart Association heart failure guideline. The NYHA classification describes functional limitation and is applicable to stage B through stage D patients, whereas the staging system describes disease progression somewhat independently of functional status.
Assessment of fluid retention through measurement of jugular venous pressure, auscultation of the lungs, and examination for peripheral edema is central to the physical examination of heart failure patients.
Given the limitation of physical signs and symptoms in evaluating heart failure clinical status, a number of noninvasive and invasive tools are under development for the assessment of heart failure. One such tool that has proven useful in determining the diagnosis and prognosis of heart failure is the measurement of plasma B-type natriuretic peptide (BNP) levels. Multiple studies demonstrate the utility of BNP measurement in the diagnosis of heart failure. The diagnostic accuracy of BNP at a cutoff of 100 pg/mL was 83.4 percent. The negative predictive value of BNP was excellent. At levels less than 50 pg/mL, the negative predictive value of the assay was 96%.
Based largely on the findings of the BNP Multinational Study, clinicians were advised that a plasma BNP concentration below 100 pg/mL made the diagnosis of congestive heart failure unlikely, while a level above 500 pg/mL made it highly likely. For BNP levels between 100 pg/mL and 500 pg/mL, the use of clinical judgement and additional testing were encouraged.
Additionally, plasma BNP is useful in predicting prognosis in heart failure patients. However, serial measurement of plasma BNP as a guide to heart failure management has not yet been proven useful in the management of acute or chronic heart failure.