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 (r(2)=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.