Marked expression of plasma brain natriuretic peptide is a special feature of hypertrophic obstructive cardiomyopathy

We examined whether plasma brain natriuretic peptide levels are abnormally elevated in hypertrophic obstructive cardiomyopathy compared with other cardiac diseases. We previously reported that plasma brain and atrial natriuretic peptide levels were elevated in hypertrophic cardiomyopathy. We compared plasma concentrations of brain and atrial natriuretic peptide and hemodynamic and echocardiographic data in 50 patients with hypertrophic obstructive cardiomyopathy (n = 15, mean [±SD] intraventricular pressure gradient 37 ± 16 mm Hg), hypertrophic nonobstructive cardiomyopathy (n = 15), aortic stenosis (n = 10, mean pressure gradient 41 ± 18 mm Hg) and hypertensive heart disease (n = 10, mean systolic/diastolic blood pressure 203 ± 16/108 ± 11 mm Hg, respectively) and 10 normal subjects. Plasma brain natriuretic peptide levels were higher in the hypertrophic obstructive cardiomyopathy group (397.1 ± 167.8 pg/ml*) than in the hypertrophic nonobstructive cardiomyopathy (60.0 ± 48.1 pg/ml*†), hypertensive heart disease (53.9 ± 31.4 pg/ml*†), aortic stenosis (75.4 ± 54.3 pg/ml*†) and normal groups (9.8 ± 6.4 pg/ml† [* p < 0.05 vs. normal group, †p < 0.05 vs. hypertrophic obstructive cardiomyopathy group]). Although plasma atrial natriuretic peptide levels were higher in the hypertrophic obstructive cardiomyopathy group than the other patient groups, the brain/atrial natriuretic peptide ratio in the hypertrophic obstructive cardiomyopathy group was higher (4.5 ± 2.3) than those in the other three patient groups (1.1 to 1.4) and the normal group (0.7 ± 0.5). Left ventricular end-diastolic pressure and left ventricular end-diastolic volume index were similar among the four patient groups. The interventricular septal thickness and the ratio of interventricular septal thickness to left ventricular posterior wall thickness were similar between the hypertrophic obstructive and nonobstructive cardiomyopathy groups. Abnormal elevations of plasma brain natriuretic peptide levels are difficult to explain on the basis of hemodynamic and echocardiographic data and are a special feature of hypertrophic obstructive cardiomyopathy.