What long endurance exercise will do, is help your heart to produce new circulation, called collaterals. They can be big ones in a web that go around a blockage, or dozens and dozens of little ones that provide circulation at the capillary level.
I have the capillary type. A co-worker's husban has the big web type around a 100% blockage. But some people don't get them at all.
Do NOT ignore any chest discomfort
or shortness of breath
. Ask your doctor to prescribe a nitroglycerin
Eat more high antioxidant fruit, adopt a heart healthy diet, very low fat diet.