The history and clinical examination are the most important components in the diagnosis of CHF. Diagnostic studies that are helpful in evaluating CHF and its underlying causes include echocardiography, chest radiography, electrocardiography, blood gas analysis, complete blood counts, serum electrolyte tests, blood urea nitrogen and creatinine tests, liver function tests, and urinalysis.
Echocardiography is critically important in identifying the many cardiac causes and comorbidities of CHF (eg, IHD, valvular heart disease, cardiomyopathies, cardiac arrhythmias) and measuring the left ventricular EF. Although the EF can also be measured by radionuclide ventriculography or contrast ventriculography, echocardiography is the most useful and least invasive method for determining and sequentially following EF and the systolic state of the ventricles. Measuring the EF allows the clinician to differentiate between HFrEF and HFpEF, a distinction that is of paramount significance in managing the CHF patient.
Measurement of serum brain natriuretic peptide (BNP) or its metabolite (NT-proBNP), a peptide associated with reduced left ventricular EF and increased left ventricular filling pressure, may be helpful in confirming the diagnosis of CHF, assessing its severity and prognosis, and guiding the treatment. BNP may also be useful as a screening tool to identify early CHF or prevent its development. If the primary mechanism of heart failure is unclear, additional tests may prove useful in selected patients. Such tests may include exercise stress testing, cardiac nuclear imaging studies, right-sided and/or left-sided heart catheterization, Holter monitoring, pulmonary function tests, HIV testing, and thyroid function tests. Coronary angiography can be helpful in identifying patients with ongoing cardiac ischemia and CHF, for which revascularization may lead to symptomatic improvement.
The ECG may reveal acute ischemic changes, acute or previous ventricular hypertrophy, chamber enlargement, and atrial fibrillation or other arrhythmias. Typical chest radiograph findings are prominent pulmonary vessels, interstitial or alveolar pulmonary edema, cardiomegaly, and pleural effusions. Patients with severe pump failure may have abnormal serum electrolyte levels owing to poor renal perfusion. Abnormalities in the blood or urine may help detect severe anemia or renal failure as precipitating factors in CHF. Abnormal liver enzyme levels are common if venous congestion is present as a result of right ventricular failure.
Excerpted from BCSC 2020-2021 series: Section 1 - Update on General Medicine. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.