Maad Rayan Publishing Company Biomedicine Advances 3080-0382 3 2 2026 04 27 MRSA endocarditis with coronary sinus abscess causing transient complete atrioventricular block: A rare case 83 86 10.34172/bma.65 EN Orkun Canbolat https://orcid.org/0009-0004-3530-0094 Şeyma Yeşil https://orcid.org/0000-0002-3494-3985 Yelda Saltan Özateş https://orcid.org/0000-0001-5080-542X Ufuk Yıldız https://orcid.org/0000-0003-3709-4293 Duygu Inan https://orcid.org/0000-0003-3921-6469 Alev Kılıcgedik https://orcid.org/0000-0002-4380-7045 Journal Article 10.34172/bma.65 2026 03 06 2026 04 01 Infective endocarditis complicated by a coronary sinus abscess is extremely rare and can lead to conduction issues. We report a 63-year-old hemodialysis patient with Methicillin-resistant Staphylococcus aureus infective endocarditis who developed complete atrioventricular block. Transesophageal echocardiography and cardiac computed tomography showed vegetations on the posterior mitral annulus, severe mitral regurgitation, and a coronary sinus abscess. Atrioventricular conduction recovered spontaneously, probably due to abscess drainage into the left atrium. Despite surgery, the patient died from cardiogenic shock. This case highlights the diagnostic and therapeutic challenges of periannular complications.