Can chronic anti-tumour necrosing factor therapy and colic polyps overwhelm a normal functioning mitral valve? A case report of an endocarditis complicated by a ruptured intracranial mycotic aneurysm

BACKGROUND: Rapid identification of endocarditis is challenging but also an important opportunity to change disease course. This is especially true when immunosuppression undermines diagnosis by mitigating symptoms that commonly accompany infectious disease, sometimes in the absence of predisposing heart valve disease as in this case presented here. CASE SUMMARY: A middle-aged man with chronic etanercept treatment for ankylosing spondylitis, with previously well-documented normal cardiac valves, presented with afebrile chills, night sweating, weight loss, and a new mitral regurgitation at auscultation. This Streptococcus bovis-related endocarditis, in the presence of benign colic polyps, rapidly became complicated by a ruptured infectious intracranial mycotic aneurysm. The patient was successfully cured by endovascular embolization. Severe mitral regurgitation required an uneventful mitral annuloplasty 1 month thereafter. DISCUSSION: Immunosuppression from etanercept treatment was likely responsible for this unspecific clinical presentation and potentially devastating intracranial mycotic aneurysm. This complication is infrequently reported within 6 months of anti-tumour necrosing factor therapy initiation but occurred after more than 11 years of therapy in our patient. This case is a timely reminder of the clinical challenges of endocarditis in immunosuppressed patients and highlights a potential long-term complication of etanercept.