Heart Question Need Answer Swiftly?

I have had a cardiac cath and stress test which show I have a blockage of 50%. I recently had a MUGA (Multiple gated Access scan) in which my ejection fraction is 32% making me a new candidate for SCD Syndrome. How Long after my new ace inhibitor and water pills started Friday night June 10 2011. Lisinopril/Hydroclorothiazide and Coreg will it be usually until my DR implants my Automatic Implantable Cardiac Defibrillator? Will I have to wait long or is this done pretty swiftly? Thanks.