This study will compare two treatments: pacemaker implantation and percutaneous
transluminal septal ablation (PTSA) for patients with hypertrophic cardiomyopathy (HCM), a
condition in which the heart muscle thickens and obstructs the flow of blood out of the
heart. The reduced blood flow can cause chest pain, shortness of breath, palpitations,
tiredness, lightheadedness and fainting.
Patients with HCM who cannot be helped by drug therapy may participate in the study. The
standard treatment for such patients is septal myectomy, an operation in which the surgeon
shaves the muscle obstructing the blood flow. Another treatment option is implantation of a
type of pacemaker that causes the heart to contract in a certain way that reduces blood flow
obstruction and improves symptoms. The pacemaker is implanted under local anesthesia and
usually takes less than an hour. PTSA is an experimental treatment that may provide a third
option. In PTSA, a thin tube (catheter) is inserted into the blood vessel that feeds the
heart muscle causing the blood flow obstruction. A small amount of alcohol is injected
through the catheter to destroy some of the muscle and relieve the obstruction.
Candidates will have the following screening tests: chest X-ray, electrocardiogram,
echocardiogram, exercise tests, exercise radionuclide angiography, exercise thallium
scintigraphy, Holter monitoring, cardiac catheterization, electrophysiology study, and
coronary angiography. Participants will be assigned to one of the two treatments groups:
pacemaker implantation or PTSA. Patients in the PTSA group will also have magnetic
resonance imaging scans at the start of the study, 3 to 7 days after PTSA, and at the end of
the study, in order to observe changes in the heart's shape. All patients will fill out a
questionnaire answering questions about their quality of life.
Patients' progress will be followed with monthly phone calls. In addition, various tests,
such as exercise tests and echocardiography, will be done during repeat visits at three and
six months to measure treatment results. Patients will again complete quality-of-life
questionnaires at both of those visits.
Patients with obstructive HCM and drug-refractory symptoms are referred for left ventricular
myotomy and myectomy (LVMM) or mitral valve replacement. As alternative therapies to
cardiac surgery, we propose to compare the abilities of dual chamber (DDD) pacing and
percutaneous transluminal septal ablation (PTSA) to reduce left ventricular (LV) outflow
pressure gradients and to improve exercise performance in patients with obstructive HCM and
severe symptoms who have failed to benefit from pharmacotherapy.
Patients of either gender, aged 18-80 years.
NYHA functional class III/IV, or syncope, or greater than or equal to 2 presyncope despite
verapamil and/or Beta-blocker therapy.
LV outflow tract gradient greater than or equal to 30 mm Hg at rest or greater than or
equal to 50 mm Hg following isoproterenol infusion to a heart rate of greater than 100
No patients with mid-cavity obstructive HCM.
No patients with LV septal wall thickness less than 15 mm estimated by echocardiography.
No patients with greater than 50 percent luminal narrowing in a major coronary artery
No patients with chronic atrial fibrillation.
No patients with a positive pregnancy test.