A 36-year-old male patient was hospitalized due to persistent chest tightness and dyspnea last-ing over 10 days.An echocardiogram revealed significant aortic valve regurgitation,the presence of vegetation on the aortic valve,severe mitral valve regurgitation,and enlargement of both the left atrium and left ventricle.Follow-ing a comprehensive multidisciplinary consultation,the focus was directed towards the aortic valve vegetation as the primary concern,with particular attention given to the potential diagnosis of blood culture-negative infective endocarditis(IE)and non-bacterial thrombotic endocarditis,while differentiating it from rheumatic heart disease.Ultimately,the vegetation was excised during a surgical aortic valve replacement procedure,which facilitated histopathological examination,biological culture,and high-throughput metagenomic sequencing of pathogenic mi-croorganisms.The definitive diagnosis was established as aortic valve infective endocarditis(Q fever IE)leading by infection of Coxiella burnetii.