Echo-Negative Endocarditis: Analysis of 538 Consecutive Transesophageal Echocardiographies.

Background:

Despite major advances in the design of diagnostic tools, the diagnosis of infective endocarditis (IE) remains a challenge. The crucial role of transesophageal echocardiography (TEE) in the diagnosis of IE is well established. However, detection of vegetations by TEE may be suboptimal in the presence of preexisting valvular conditions, thus hampering diagnostic efforts. The well cited ICE-PCS study (2009) found that 13% of IE cases were echo-negative. We aimed at identifying and characterizing cases of TEE-negative endocarditis.

Methods: 

We retrospectively studied 538 sequential TEE examinations (Echo-Son C256), performed for a variety of reasons, during the years 2009-2014. Patient-matched blood cultures and serologies were reviewed. Of 65 patients with typical organisms in blood cultures, TEEs have detected vegetations in 15 patients. Of the 50 TEE-negative patients, 38 had noncardiac infectious diagnoses, but 12 were considered to have possible IE (modified Duke's criteria). The records of these 12 patients were investigated.

Results: The mean age of the 12 patients was 74 years (±12 SD, 8 males). All underwent both TTE and TEE and showed predisposing cardiac abnormalities: six on a native valve (83% mitral), and six had a prosthetic valve (83% aortic); additionally, two had pacemaker implants. Ten patients (83%) presented with fever, 4 had chills, 2 had weight loss, one patient had syncope and one CVA. The mean number of blood cultures drawn was 4.1 (range: 2-12) and 42/53 were positive (8/12 patients had ≥3 positive cultures). The pathogens identified included S. viridians (n=3), E. faecalis (n=2), S. bovis (n=2), and one of each: C. hominis, S. aureus, S. pneumonia, H. parainfluenzae, and C. burnettii (serology). One patient's diagnosis was confirmed by PET-CT. All patients were treated with appropriate antibiotics, without surgery. The 1-month fatality ratio was 17%

Conclusion: 

- In these series, echo-negative endocarditis (ENE) constituted 44% of all IE cases. ENE occurs in elderly patients, on damaged valves and may be caused by a variety of organisms. These findings highlight the need to embrace the term: "echo-negative endocarditis" in patients with compatible clinical picture, damaged heart valves and positive blood cultures.