Noninfective Endocarditis (Nonbacterial Thrombotic Endocarditis) By Guy P Armstrong, MD, Waitemata District Health Board and Waitemata Cardiology, Auckland Reviewed / Revised Jul 2022 | Modified Sep 2022 View Patient Education Etiology Symptoms and Signs Diagnosis Prognosis Treatment Key Points Topic Resources Overview of Infective and... Noninfective endocarditis refers to formation of sterile platelet and fibrin thrombi on cardiac valves and adjacent endocardium in response to trauma, circulating immune complexes, vasculitis, or a hypercoagulable state.