Frequency and Clinical Significance of Right Atrial Embryonic Remnants Involvement in Infective Endocarditis.

Background: The involvement of atrial embryonic remnants in infective endocarditis (IE) has seldom been reported. The study aim was to evaluate the prevalence of vegetations on right atrial embryonic remnants (RAER) in patients with a definitive diagnosis of IE.

Methods: Since 1998, all consecutive patients with suspected IE were referred to the authors' institution to undergo transesophageal echocardiography (TEE). Patients with a high probability of IE but with a negative result underwent a further TEE examination within 10 days. The involvement of RAER was investigated systematically.

Results: Among a total of 585 patients evaluated, definitive criteria for IE were present in 210 (35.9%). Right-sided IE was detected in 33 patients (15%); these included 21 infections on the tricuspid valve (65%), 10 cases of intracardiac electronic device infection (29%), one infection on the Thebesian valve (3%), and one on the pulmonary valve (3%). The incidence of right-sided IE was 0.84 per 100,000 population per year. RAER involvement was detected in five patients (15% of right-sided endocarditis), representing 2.5% of the complete IE series. The incidence of RAER endocarditis was 0.13 new cases per 100,000 population per year. The Eustachian and Thebesian valves were involved in four cases. Two patients presented with pulmonary embolism and died in hospital. Transthoracic echocardiography (TTE) allowed the detection of RAER vegetations in two cases.

Conclusions: Although the prevalence of embryonic remnants involvement in IE is underestimated, it may carry an important embolic risk if undetected. As TTE demonstrated only a low sensitivity in the diagnosis of embryonic remnant involvement, TEE should be performed systematically and RAER involvement carefully sought. TEE is recommended in all patients with a high clinical suspicion of right-sided IE. Video 1: Mid-esophageal TEE view. Multiple vegetations attached onto the pacemaker leads (broken arrow) and on the Eustachian valve (solid arrow). Video 2: Mid-esophageal TEE view. A vegetation attached onto the tricuspid valve (broken arrow) and on the Eustachian valve (solid arrow).