SMS: Substrate Modification Study in Patients Getting an Implantable Cardioverter Defibrillator (ICD)

Inclusion Criteria: * Coronary artery disease documented by coronary angiography. For the purpose of this study, coronary artery disease will be defined as the presence of a 50% or more diameter stenosis of the left main or of a 75% or more diameter stenosis of the left anterior descending, circumflex or right coronary arteries, or the history of a surgical or percutaneous revascularization procedure. * Left ventricular ejection fraction \< 40% as estimated by echocardiography or contrast ventriculography within the previous 30 days. * Clinical unstable VT without reversible factors (acute ischemia or antiarrhythmic medications as defined below). Unstable VT can have one of the following clinical presentations: * Hypotensive VT without major neurologic dysfunction; * Syncope; or * Cardiac arrest. Exclusion Criteria: * Age \< 18 years or \> 80 years * Protruding left ventricular (LV) thrombus on pre-ablation echocardiogram * Acute myocardial infarction within the preceding 2 months * Class IV New York Heart Association (NYHA) heart failure * Valvular heart disease or mechanical heart valve precluding access to the left ventricle * Unstable angina * Cardiac surgery within the past 2 months * Serum creatinine \> 220 mmol/L (2.5 mg/dL) * Thrombocytopenia or coagulopathy * Contraindication to heparin * Pregnancy * Acute illness or active systemic infection * Other disease process likely to limit survival to less than 12 months * Significant medical problem that, in the opinion of the principal investigator, would preclude enrollment into the study * Participation in another investigational study * Unwillingness to participate or lack of availability for follow-up