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Nonsurgical septal reduction therapy for hypertrophic obstructive cardiomyopathy: short-term results in 50

Christopher D Nielsen1, Donna Killip, William H Spencer

  • 1Division of Cardiology, Medical University of South Carolina, Charleston, South Carolina 29425, USA. nielsenc@musc.edu

Clinical Cardiology
|July 4, 2003
PubMed

Insights

Refined nonsurgical septal reduction therapy (NSRT) significantly reduces left ventricular outflow tract gradients and improves symptoms in hypertrophic obstructive cardiomyopathy (HOCM) patients. This technique also lowers the incidence of complete heart block (CHB), a major complication of the procedure.

Area of Science:

  • Cardiology
  • Interventional Cardiology
  • Cardiac Imaging

Background:

  • Nonsurgical septal reduction therapy (NSRT) is an effective treatment for hypertrophic obstructive cardiomyopathy (HOCM), improving left ventricular outflow tract (LVOT) gradients, septal thickness, and symptoms.
  • A significant complication of NSRT is complete heart block (CHB), historically reported in up to 33% of patients, necessitating permanent pacemaker implantation.
  • Technological and procedural refinements, including echocardiographic contrast use, slower alcohol injection, and improved balloon technology, aim to mitigate this risk.

Purpose of the Study:

  • To evaluate the efficacy and safety of NSRT using refined techniques: echocardiographic contrast localization, slow alcohol injection, and short balloon length.
  • To determine if these refinements reduce the incidence of complete heart block (CHB) compared to earlier studies.
  • To assess the impact of NSRT on LVOT gradients, septal thickness, symptoms, and exercise capacity.

Main Methods:

  • Fifty NSRT procedures were performed on 46 HOCM patients utilizing echocardiographic contrast for localization, slow alcohol injection, and short balloon catheters.
  • Echocardiography was conducted pre-procedure, immediately post-procedure, and at 3-month follow-up.
  • Treadmill testing, creatine kinase (CK) measurements for infarct size, and monitoring for CHB and other complications were performed.

Main Results:

  • A significant reduction in LVOT gradient was observed, from 84.2 mmHg at baseline to 18.5 mmHg immediately after NSRT (p < 0.001), with sustained reduction at 3 months.
  • Septal thickness decreased from 2.21 cm to 1.67 cm at 3 months (p < 0.001), and New York Heart Association symptom class improved from 3.2 to 1.1 (p < 0.001).
  • The incidence of CHB requiring permanent pacing was 6.7% (3 out of 45 patients without prior pacing devices), significantly lower than historical rates. Pre-existing left bundle-branch block (LBBB) was identified as a predictor for CHB.

Conclusions:

  • The refined NSRT technique, incorporating contrast echocardiography, slow alcohol injection, and short balloons, effectively improves hemodynamic parameters, reduces septal thickness, and alleviates symptoms in HOCM patients.
  • This refined approach significantly lowers the incidence of CHB requiring permanent pacemaker implantation.
  • Left bundle-branch block (LBBB) is a significant risk factor for developing CHB post-NSRT.
Abstract

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