Looks like your LAD may have a blockage because the top front of your left ventricle is ischemic (short of blood supply). Keep in mind that this only occurs when the heart is working hard and is mild/moderate.
This logical next step is probably a heart catheterisation. They will guide a catheter from your inner thigh or from your arm to your heart. Then they will feed a contrast agent through the catheter while making X-ray pictures of your coronary arteries. This will show if there are blockages in your arteries, how serious they are and where they are located. Several other measurements can be done to analyse the impact of the blockage to the blood supply of your heart.
It means that your heart is not getting enough oxygen under stress.
This is possibly a dangerous situation so the logical next step is to find out where exactly the problem is located and what to do about it.