The risk of failed coronary artery bypass grafts

Hi Dr T, 76 yr old male. undergone CABG for 3 vessel injury in April 2005. From past 1 year, having breathing, perspiration and uneasiness in heart region, after mild exertion.  Like walking for 10 minutes or more and occasional fits of internal burning heat and excessive perspiration.
A recent checkup shows1) Good lipid profile – Total cholestral 128, non diabetic, 65 KG , 165 cm ht , 76 age with parkinson in mild form for 20 years and lumbar issues2) normal XRAY CHEST PA view i.e. both lung fileds are normal. Cardiac shadow is within normal limits.3)Ultrasonography of abdominal & Pelvi organs are normal4)uric acid 8.7, T3 – 72.41, T4- 7.70 & TSH 6.05, Sodium 141, Potassium 5.6  and Chlordie 104; blood urea nitrogen 39.0;  creatinine – 1.9, Fasting glucose 83,  ALT /SGPT  – 24.0, hemoglobin 13.1, hemotocrit 40.1 urin analysis normal5)  2 D echo shows LVEF 40 %, grade I DD +Medicine taken are
tab REL PLUS 1 od
cap COUR 60  1 od
Tab lasix 40  1 od
Carbdiolol 6.25  1/2 BD
Nicorandial 20 mg BD
Losarton 50 mg 1 HS
Atorvastan 20 mg 1 HS
Question:  can I be cured by medicines alone? If so pls suggest the present prescription is oK or suggest changes,or is  angiography/2nd by pass surgery must at this stage/age? Tthanks