Evaluation of suspected left ventricular systolic dysfunction

Morgan and coworkers²⁸ assessed the prevalence and clinical characteristics of LVSD among elderly patients (those aged 70 years to 84 years) in a primary care setting by echocardiographic assessment of ventricular function. They found that no single clinical symptom or sign was both sensitive and specific, and concluded that diagnosis should not be based on clinical history and examination alone. They found that a substantial number of elderly individuals had asymptomatic or misdiagnosed LVSD, and suggested this might be due to the extremely limited sensitivity and specificity of clinical history taking and examination. For example, only 11% of patients with LVSD had a raised jugular venous pressure, and bilateral ankle edema was common but nonspecific. Researchers have therefore concluded that although these clinical findings are useful in acute severe heart failure, they have only a small role in detecting LVSD in the community.¹⁸

TABLE 1
The use of clinical symptoms and signs to diagnose heart failure, by study

Laboratory and imaging evaluation

Although an important and valuable part of the evaluation, the history and physical examination alone are insufficient to confirm a diagnosis in most cases. Recommended initial tests for patients with signs or symptoms of heart failure include complete blood count (CBC), serum electrolytes, serum creatinine, serum albumin, liver function tests, urinalysis, electrocardiogram, and chest x-ray (Figure).

Blood tests. For those older than 65 years or with atrial fibrillation or evidence of thyroid disease, thyroid function tests should also be performed because heart failure due to thyrotoxicosis is frequently associated with rapid atrial fibrillation and hypothyroidism may also present as heart failure.^8,10 The other routine blood tests are important as a way to exclude alternative diagnoses; they also help with the search for predisposing or exacerbating causes of the heart failure. These baseline tests also help guide future therapeutic decision making. For example, electrolyte and renal function results are pertinent when initiating angiotensin-converting enzyme (ACE) inhibitors. Anemia can exacerbate pre-existing heart failure, and measurement of renal function is essential to distinguish fluid overload due to heart failure from renal failure. Liver enzymes may be affected by hepatic congestion. Urinalysis is valuable in the detection of underlying renal disease or diabetes.⁸

Electrocardiography. An electrocardiogram (ECG) is another recommended part of the evaluation of the suspected heart failure patient.^8-14 Considerable attention has been paid to examining the value of this test in the diagnosis of LVSD.^29-32 Davie and colleagues²⁹ assessed the value of the ECG in identifying patients with possible heart failure by examining referrals for echocardiography by primary care practitioners. A total of 534 patients were referred for echocardiography for possible heart failure, of whom 18% (n = 96) had LVSD. They showed that LVSD was extremely unlikely if the ECG result was normal, but that 1 in 3 patients with an abnormal result had significant LVSD. Thus, a normal ECG result virtually excludes chronic heart failure due to LVSD. However, the ECG is not a substitute for echocardiography, as an abnormal result does not accurately predict the presence of LVSD (Table 2).

Others have confirmed these findings.^30,32 Talreja and colleagues³⁰ found that of 330 consecutive in-patients referred for echocardiographic assessment of left ventricular function, 124 (41%) had LVSD. Only 2 of 124 patients with LVSD had a normal electrocardiogram result. When the ECG result is normal, the authors suggest that echocardiography is not needed. However, they concede that physicians are unlikely to adhere to this because many may not be as sophisticated in interpreting the ECG and may feel it important to get an accurate measure of ejection fraction. Guidelines published by the European Society of Cardiology¹⁰ state that a normal ECG result in patients with suspected heart failure should lead us to doubt the accuracy of the diagnosis.

Chest x-ray. The chest x-ray is most valuable as a test to exclude pulmonary causes. However, the existing evidence suggests it is not a reliable way to exclude LVSD.^24,26,33,34 (Table 2) provides information about the value of radiography in predicting LVSD. A systematic review of the literature concluded that redistribution and cardiomegaly were the best chest radiographic findings for diagnosing increased preload and reduced ejection fraction, respectively.³⁴ However, neither finding alone could adequately exclude or confirm LVSD. Studies published since that review have confirmed this finding.³³ Although part of the evaluation of the heart failure patient, radiography is only one part of the diagnostic process and cannot be used to provide definitive diagnostic information.