[Infective endocarditis in patients with hypertrophic obstructive cardiomyopathy: five cases report]

To analyze the clinical characteristics of infective endocarditis in patients with hypertrophic obstructive cardiomyopathy.

Clinical characteristics from 5 patients with infective endocarditis and hypertrophic obstructive cardiomyopathy hospitalized from January 2000 to December 2010 in our hospital were analyzed.

Four patients were diagnosed with left ventricular outflow tract obstructive cardiomyopathy with outflow pressure gradient from 36 to 140 mm Hg (1 mm Hg = 0.133 kPa) and left atrial size 44 - 68 mm. Another patient was diagnosed as ventricular hypertrophic cardiomyopathy with significant right-ventricular outflow tract hypertrophy (30 mm), high pressure gradient (164 mm Hg) and enlarged right atrial (56 mm × 53 mm), there was a 17 mm × 8 mm vegetation on right-ventricular outflow tract in this patient. Blood cultures were positive for streptococcus viridans in all five patients, and enterococcus faecium was revealed in one aortic valve vegetation culture. Transthoracic echocardiogram was performed 2 - 4 times for each patient, the vegetations of two patients was detected only by transesophageal echocardiography. The mitral valve vegetation was detected in two patients, the aortic and mitral valve vegetations were detected in one patients, mitral and tricuspid vegetations in one patient and right ventricular outflow tract vegetation in one patient. The four hemodynamically stable patients were successfully treated with antibiotic therapy, one patient received urgent surgery (replacement of the aortic and mitral valve as well as septal myectomy). All patients recovered and follow-up (1 - 6 years) was available in 4 patients and no complication was observed.

The risk of infective endocarditis complicating hypertrophic obstructive cardiomyopathy is the highest in patients with both outflow obstruction and marked valve insufficiency, these patients should receive prophylactic antibiotic therapy during procedures that predispose to infective endocarditis.