ABSTRACT
Haemophilus parainfluenzae, one of the member of the HACEK group of gram-negative oropharyngeal species, is a rare cause of subacute native valve endocarditis. Infective endocarditis caused by H. parainfluenzae appears to carry a high incidence rate of cerebral embolism, often making the timing of surgical intervention difficult. A 52-year-old male was diagnosed with acute endocarditis caused by H. parainfluenzae complicated with acute cerebral infarctions. After institution of antibiotic therapy, this patient was mechanically ventilated because of the sudden onset of dyspnea. Repeated two-dimensional echocardiography demonstrated rate-dependent mitral stenosis without interval change of vegetations on the mitral valve. Making a decision regarding the timing of surgical intervention was difficult because of a fear of clinical deterioration after early valve replacement.