Cardiology Letters 2025, 34(5):283-287

Atypical presentation of infective endocarditis complicated by dietary-induced warfarin resistance

Adrianna Perzanowska, Zuzanna Tomaszewska, Agata Antoniak, Klaudia Cierlicka

Praski Hospital of the Transfiguration of the Lord, Warsaw, Poland

Infective endocarditis (IE) is a life-threatening disease that often presents with nonspecific symptoms, leading to delayed diagnosis. We present the case of a 39-year-old male without significant comorbidities who presented with lower-limb pain, swelling, and systemic symptoms, initially misdiagnosed as pneumonia. Computed tomography (CT) angiography revealed a thrombus in the distal posterior tibial artery, but IE was suspected only after a new heart murmur was detected. Echocardiography showed vegetations on the aortic valve, mitral valve perforation, and severe aortic regurgitation. Blood cultures remained negative, likely due to prolonged prior antibiotic therapy. However, molecular analysis of excised valve tissue confirmed the presence of Streptococcus species. The patient underwent successful surgery with mechanical valve implantation and completed a six-week course of antibiotics. Postoperatively, International Normalized Ratio (INR) values remained subtherapeutic despite warfarin therapy. A detailed dietary assessment revealed excessive matcha intake (6 g/day), a source of vitamin K, which reduced warfarin efficacy. After limiting matcha to 2 g/day, the INR stabilized, and the patient was safely discharged on continued outpatient warfarin therapy. This case highlights the diagnostic complexity of IE, especially in atypical presentations and blood culture-negative cases. It also underscores the importance of monitoring vitamin K intake in patients who have undergone mechanical valve implantation and are on warfarin anticoagulation. A multidisciplinary approach, including thorough dietary assessment, is crucial for optimal management of IE cases.

Kľúčové slová: infective endocarditis; bacterial embolism and thrombosis; warfarin; dietary supplements; drug interactions

Uverejnené: May 1, 2025  Zobraziť citáciu