• Schoepf UJ, Yucel EK, Bettmann MA, Casciani T, Gomes AS, Grollman JH, Holtzman SR, Polak JF, Sacks D, Stanford W, Jaff M, Moneta GL, Expert Panel on Cardiovascular Imaging. Suspected bacterial endocarditis. [online publication]. Reston (VA): American College of Radiology (ACR); 2006. 5 p. [27 references]

This is the current release of the guideline.

This guideline updates a previous version: Higgins CB, Levin DC, Bettmann MA, Gomes AS, Grollman J, Henkin RE, Hessel SJ, Kelley MJ, Needleman L, Polak JF, Stanford W, Wexler L, Abbott W, Port S. Suspected bacterial endocarditis. American College of Radiology. ACR Appropriateness Criteria. Radiology 2000 Jun;215(Suppl):73-7.

The appropriateness criteria are reviewed annually and updated by the panels as needed, depending on introduction of new and highly significant scientific evidence.

ACR Appropriateness Criteria®

Clinical Condition: Suspected Bacterial Endocarditis

Note: Abbreviations used in the table are listed at the end of the "Major Recommendations" field.

Infective endocarditis has been classified as acute endocarditis and subacute endocarditis. Typically, acute endocarditis is produced by a virulent organism (such as Staphylococcus aureus) on a normal valve, while subacute endocarditis is produced by less virulent organisms (Streptococcus viridans or Staphylococcus epidermis) on an abnormal valve. Infective endocarditis can also be classified as infection of prosthetic valves. In recent years, infective endocarditis of normal right-sided valves has become frequent as a consequence of intravenous injection of illicit drugs. While acute endocarditis of left-sided cardiac valves nearly invariably causes congestive heart failure, heart failure may also occur with subacute infective endocarditis. The diagnostic work-up of patients with suspected infective endocarditis varies somewhat, depending upon the presence of congestive heart failure.

Infective endocarditis is fundamentally a clinical diagnosis based on the presence of positive blood cultures in association with characteristic symptoms and physical findings. Imaging is used to support the diagnosis by demonstration of vegetations of cardiac valves and, in complicated cases, perivalvular abscesses. Imaging is also used to assess the severity of valvular damage, identify complications, and recognize the presence and severity of heart failure.

Chest X-ray

The chest x-ray is used to determine cardiac chamber size and the presence and severity of pulmonary venous hypertension and edema; it is necessary for the evaluation of infective endocarditis. It is used to monitor the severity of the hemodynamic consequences of valvular regurgitation caused by infectious endocarditis and to assess response to treatment. Chest x-ray is also used to identify abnormal contour of the great arteries or cardiac chambers which might be indicative of perivalvular abscess. In right-sided endocarditis the chest x-ray is effective for demonstration of pulmonary infarcts and abscesses.

Cardiac Fluoroscopy

In rare occasions, cardiac fluoroscopy may be indicated for the evaluating prosthetic cardiac valves afflicted with endocarditis. It is used to determine excess mobility of the valve during the cardiac cycle; this finding may be highly suggestive of valve dehiscence caused by infective endocarditis.

Transthoracic Echocardiography

Transthoracic echocardiography (TTE) plays an important role in the evaluation of infective endocarditis. It can demonstrate vegetations on cardiac valves, valvular regurgitation, and perivalvular abscess. It is the most frequently used imaging study for confirming the diagnosis of infective endocarditis. The demonstration of vegetations by echocardiography establishes the diagnosis. Studies show that criteria for the diagnosis, which includes the findings on TTE and particularly transesophageal echocardiography (TEE), were significantly better than traditional criteria based upon clinical and bacteriologic criteria. While TEE has been shown to have significantly higher sensitivity than TTE for identifying vegetations, specificities were similar. The positive predictive value of echocardiography for the diagnosis has been shown to be 97% while the negative predictive value was 94%.

Several studies evaluated the diagnostic value of TTE and TEE in relation to the pretest probability of infective endocarditis based upon clinical assessment in pediatric and adult patients. These studies concluded that echocardiography is less indicated in patients with low probability of endocarditis. TTE is the procedure of choice for patients with intermediate or high probability of endocarditis. In right-sided endocarditis, TTE and TEE demonstrated a similar number of vegetations and frequency of tricuspid regurgitation.

The size and other characteristics of vegetations on echocardiography have been shown to be useful in predicting complications such as peripheral embolization. Increase or failure to decrease in size of vegetation on serial echocardiograms during antibiotic therapy has been shown to be predictive of a prolonged and/or complicated course of infective endocarditis.

Transesophageal Echocardiography

TEE is indicated and increasingly used in suspected infective endocarditis for demonstrating vegetations, perivalvular abscess, valvular regurgitation and ventricular function. It is the most sensitive imaging technique for identifying vegetations, which are the hallmark for the definitive diagnosis of infective endocarditis. Criteria for diagnosing infective endocarditis using echocardiographic features improve upon the diagnostic accuracy of using clinical criteria alone. TEE has better sensitivity than TTE for detecting vegetations. A review has claimed that in experienced hands, TEE has a greater than 90% sensitivity and specificity for detecting intracardiac lesions associated with infective endocarditis. This and another review also concluded that a negative TEE almost always means a very low probability of infective endocarditis.

TEE has been shown to be very effective for monitoring the size and other characteristics of vegetation and for detecting complications such as perivalvular abscesses. TEE has improved sensitivity and accuracy compared to TTE for identifying perivalvular abscesses. TEE is indicated for suspected infective endocarditis of prosthetic valves; it is significantly more accurate than TTE. Furthermore, monitoring the size of vegetations during treatment contributes information concerning prognosis and risk of complications, although the usefulness of repeated TTE for altering patient management decreases with the number of repetitions.

In two studies, TTE was found to be the more cost effective test in patients with intermediate or high pretest probability of infective endocarditis.

TEE is indicated in many patients with suspected infective endocarditis, especially those in whom TTE is inconclusive or in patients with suspected perivalvular abscess.

Radioisotope Scanning

Radioisotope scanning is probably indicated in the evaluation of suspected infective endocarditis. Several types of radioisotope scans may be used for identifying and localizing infected vegetations and perivalvular abscesses. Gallium 67 and indium111- labeled white cells are routinely used. Although these techniques are useful in isolated patients, they have a low sensitivity and add little to the usual diagnosis of infective endocarditis.

More recently, immunoscintigraphy using technetium99m-labeled anti-NCA-95 antigranulocyte antibodies has been proposed as a method of localization. In one study, this scan had a sensitivity of 79% and specificity of 82% compared to echocardiography, which had a sensitivity of 88% and specificity of 97%. However, the combination of echocardiography and immunoscintigraphy has a sensitivity of 100% and specificity of 82%.

Magnetic Resonance Imaging

MRI is probably indicated for the evaluation of infective endocarditis. However, its use should be limited to the evaluation of complications such as perivalvular and myocardial abscesses and infectious pseudoaneurysms. It is less accurate than TTE and TEE for identifying valvular vegetations. Cine MRI and velocity encoded cine MRI can be used for the semiquantification and quantification of the volume of valvular regurgitation, respectively.

Computed Tomography

There is limited evidence in the literature to support the use of CT for the assessment of patients with suspected endocarditis. However, particularly ECG-gated multidetector-row CT is emerging as an important tool for non-invasive cardiac assessment and is probably indicated in the evaluation of complications of infective endocarditis, such as the identification of perivalvular and myocardial abscesses and infective pseudoaneurysms. CT may be indicated in right-sided endocarditis for demonstrated septic pulmonary infarcts and abscesses.

CT is less accurate than TTE and TEE for identifying valvular vegetation. Consequently, the role of CT, like MRI, is for the evaluation of complicated cases of infective endocarditis.

Catheterization and Ventricular Angiography

Catheterization and ventriculography are indicated in infective endocarditis with congestive heart failure. They may be used to assess the severity of valvular dysfunction and ventricular function prior to surgery. These tests are not indicated for patients with uncomplicated endocarditis on native valves in whom surgical intervention is not contemplated. Catheterization and ventriculography may be indicated for endocarditis of prosthetic valves when echocardiographic results are equivocal.

Abbreviations

• CT, computed tomography
• ECG, electrocardiogram
• INV, invasive
• MRI, magnetic resonance imaging
• NUC, nuclear medicine
• US, ultrasound
• WBC, white blood cell

Algorithms were not developed from criteria guidelines.

The recommendations are based on analysis of the current literature and expert panel consensus.

• Schoepf UJ, Yucel EK, Bettmann MA, Casciani T, Gomes AS, Grollman JH, Holtzman SR, Polak JF, Sacks D, Stanford W, Jaff M, Moneta GL, Expert Panel on Cardiovascular Imaging. Suspected bacterial endocarditis. [online publication]. Reston (VA): American College of Radiology (ACR); 2006. 5 p. [27 references]

Not applicable: The guideline was not adapted from another source.

1998 (revised 2006)

American College of Radiology - Medical Specialty Society

The American College of Radiology (ACR) provided the funding and the resources for these ACR Appropriateness Criteria®.

Committee on Appropriateness Criteria, Expert Panel on Cardiovascular Imaging

Panel Members: U. Joseph Schoepf, MD; E. Kent Yucel, MD; Michael A. Bettmann, MD; Thomas Casciani, MD; Antoinette S. Gomes, MD; Julius H. Grollman, MD; Stephen R. Holtzman, MD; Joseph F. Polak, MD, MPH; David Sacks, MD; William Stanford, MD; Michael Jaff, MD; Gregory L. Moneta, MD

Not stated

This is the current release of the guideline.

This guideline updates a previous version: Higgins CB, Levin DC, Bettmann MA, Gomes AS, Grollman J, Henkin RE, Hessel SJ, Kelley MJ, Needleman L, Polak JF, Stanford W, Wexler L, Abbott W, Port S. Suspected bacterial endocarditis. American College of Radiology. ACR Appropriateness Criteria. Radiology 2000 Jun;215(Suppl):73-7.

The appropriateness criteria are reviewed annually and updated by the panels as needed, depending on introduction of new and highly significant scientific evidence.

None available

This summary was completed by ECRI on February 20, 2001. The information was verified by the guideline developer on March 14, 2001. This summary was updated by ECRI on August 11, 2006.