Infective endocarditis: findings at transesophageal echocardiography (TOE) performed before potential switch to oral antibiotics

Background Oral step-down antibiotic treatment (PO) was recommended in the 2023 European guidelines for management of stable patients with left-sided infective endocarditis (IE). The Partial Oral versus Intravenous Antibiotic Treatment of Endocarditis (POET)-trial formed the basis for this recommendation and the favorable outcome was confirmed in a large observational study following implementation of the POET criteria for switch to PO. In POET, the transition from intravenous (IV) to PO therapy was guided by specific stabilization criteria, including a transesophageal echocardiography (TOE) prior to the switch, yet the clinical value of this TOE remains unknown. Purpose This study aimed to assess the clinical value of the TOE prior to switching IV to PO administration of antibiotics in stabilized patients with IE. Methods This was a nationwide, cohort substudy of the POETry study. In POETry, all patients diagnosed with endocarditis between May 2019 to December 2020 were assessed through medical chart review. Patients were included if they had left-sided IE caused by S. aureus, Enterococcus faecalis, streptococci, or CoNS and were biochemically considered stable according to POET criteria defined as CRP <20 mmol/L, leucocytes <15 x 109/L and had a TOE without progression. The frequency of clinically important findings at the TOE was assessed. Patients were followed for six months after the TOE for occurrence of the primary outcome defined as all-cause mortality, unplanned surgery, relapse of bacteraemia or embolic event. Results A total of 310 patients were considered to fulfill stabilization criteria and potentially qualifying for switch to oral antibiotic treatment if the TOE findings did not indicate differently. Of these, TOE data was available for 193 (74%) (mean age 73 ±15 years, 67% males (table 1). Endocarditis was located on the aortic valve (n =100, 53%), the mitral valve (n = 76, 40%) or both valves (n=17, 8%). The dominant affecting pathogen was streptococcus (n = 86, 44.8%) followed by s. aureus (n = 58, 29.9%). TOEs were performed at a mean of 19±9 days following treatment initiation. The TOE was without progression in 192 (99.5%) cases and 172 (90%) were transitioned to oral antibiotic treatment, whilst 21 (10%) remained on IV at physicians discretion. The TOEs identified one case (0.52%) with a definite new-onset root abscess not present at the time of diagnosis. The patient remained on IV antibiotics, was not candidate for surgery and discharged with suppressive antibiotic therapy. At 6-months follow-up, the patient was alive. These are preliminary results; entire study findings will be presented at ESC. Conclusions Findings indicate that only a small percentage of patients with infective endocarditis fulfilling other POET criteria for transitioning from IV to PO therapy have findings on the TOE that challenge the swift to oral therapy. This small proportion may be identified by other means, potentially making the TOE unnecessary Patient characteristics and TOE findings