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.