Tehran University of Medical Sciences The Research in Heart Yield and Translational Medicine (RHYTHM) 3115-7270 20 3 2024 05 03 242 248 Laurentia Fidella Averina Setia Santoso Faculty of Medicine, Universitas Padjadjaran Ribal Hassane Al Mokdad Faculty of Medical Sciences, Lebanese University Mustafa Saleh Faculty of Medical Sciences, Lebanese University Ahmad Mohamad Ezzedine Faculty of Medical Sciences, Lebanese University Mohammed Shawki Dabbous Faculty of Medical Sciences, Lebanese University 2024 07 11 2024 09 03 Background: Right-sided infective endocarditis (IE) is uncommon. Furthermore, Streptococcus agalactiae (S agalactiae) rarely causes IE, with only 2% to 9% of bacteremia cases manifesting as endocarditis. Case Presentation: A 30-year-old Lebanese woman presented to the emergency department with high-grade fever and chills. Blood tests were obtained, urinalysis showed leukocytes, and treatment for urinary tract infection was initiated. The patient was hospitalized 3 days later and transferred to the ICU. Echocardiography revealed severe right-sided cardiomegaly, flail tricuspid leaflets with ruptured chordae, and a large coaptation defect. She was diagnosed with right-sided IE due to S agalactiae and underwent tricuspid valve replacement. Unfortunately, the patient died from acute decompensated heart failure. Conclusion: This case represents an unusual instance of right-sided IE due to S agalactiae in Lebanon, for which definitive treatment guidance remains limited. https://jthc.tums.ac.ir/index.php/jthc/article/view/2126 https://jthc.tums.ac.ir/index.php/jthc/article/download/2126/1227