Association Between Vegetation Size And Outcome In The POET Trial

Background Step-down oral antibiotic therapy is associated with a non-inferior long-term outcome compared to continued intravenous antibiotic therapy in the treatment of left-sided infective endocarditis (IE). We aimed to analyze whether step-down oral therapy compared to continued intravenous antibiotic therapy is also associated with a non-inferior outcome in patients with large vegetations (vegetation length ≥ 10 mm) or among patients undergoing surgery before step-down oral therapy. Methods We included patients without presence of aortic root abscess at diagnosis from the POET study. Multivariable Cox regression analyses were used to find associations between large vegetation, cardiac surgery, step-down oral therapy and the primary endpoint (composite of all-cause mortality, unplanned cardiac surgery, embolic event or relapse of positive blood cultures during follow-up). Results A total of 368 patients (age 68±12, 77% men) were included. Patients with large vegetations (n = 124) were more likely to undergo surgery compared to patients with small vegetations (n=244) (65% vs 20%, p<0.001). During a median 1406 days of follow-up, 146 patients reached the primary endpoint. Large vegetations were not associated with the primary endpoint (HR 0.74 [95% CI 0.47-1.18], p=0.21). Step-down oral therapy was non-inferior to continued intravenous antibiotic in all subgroups when stratified by the presence of a large vegetation at baseline and early cardiac surgery. Conclusion Step-down oral therapy safe in the presence of a large vegetation at diagnosis and among patients undergoing early cardiac surgery.