B-type natriuretic peptide after percutaneous transluminal septal myocardial ablation

Plasma level of B-type natriuretic peptide is a sensitive marker of left ventricular dysfunction and the level is markedly elevated in patients with hypertrophic obstructive cardiomyopathy. Percutaneous transluminal septal myocardial ablation, a catheter-based treatment of hypertrophic obstructive cardiomyopathy, has been widely used as a new therapeutic option for the disease. This study was designed to evaluate clinical implications of natriuretic peptides after the new treatment.

Seven consecutive patients with hypertrophic obstructive cardiomyopathy unresponsive to usual medical treatments (age: 57.9+/-22.0 years) were enrolled in the study. Serial changes in atrial and B-type natriuretic peptide in plasma were examined after percutaneous transluminal septal myocardial ablation.

Atrial and B-type natriuretic peptides levels (pg/ml, mean+/-S.D.) at baseline were higher in hypertrophic obstructive cardiomyopathy than in control (80.0+/-43.0 vs. 12.8+/-5.2, P<0.0001; 858.0+/-458.4 vs. 12.4+/-7.0, P<0.0001; respectively). Left ventricular outflow-tract pressure gradient (mmHg) immediately decreased from 115.3+/-23.3 to 30.6+/-12.4 (P<0.0001) after the treatment and concomitantly B-type natriuretic peptide level decreased (858.0+/-458.4 to 264.1+/-137.7, P=0.0084). The level re-increased and peaked at the 2nd day (634.4+/-429.6) and gradually decreased again until 4 weeks. Reduction rate of left ventricular outflow-tract pressure gradient between before and 4 weeks after percutaneous transluminal septal myocardial ablation positively correlated with that of B-type natriuretic peptide (r(2)=0.817, P=0.0053). Changes in atrial natriuretic peptide were not significant in contrast to those of B-type natriuretic peptide.

Plasma B-type natriuretic peptide level could be useful to predict the effects of percutaneous transluminal septal myocardial ablation in patients with hypertrophic obstructive cardiomyopathy.