B-type natriuretic peptide after percutaneous transluminal septal myocardial ablation

Background: 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. Methods: 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. Results: 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 (r2=0.817, P=0.0053). Changes in atrial natriuretic peptide were not significant in contrast to those of B-type natriuretic peptide. Conclusions: 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.