Ecg suggests mid and apical septum and anteroseptum hypokinesia. what are the best test to identify where the artery blockage might be?

Cardiac cath: The standard is still cardiac catheterization. Cardiac ct and cardiac mri/mra are less invasive but not as good as cardiac cath using real time fluoroscopy. Cardiac cath uses a hollow, flexible, "wire" or catheter that is inserted into your groin and then menuvered up into the heart. The tip of the catheter releases a liquid that can be seen by x-ray. It is great at seeing/fixing narrowed artery.

Coronary angiogram: Its a invasive test but this will identify the blockage in left anterior descending artery.

CAD: What you are calling ECG has to be echocardiogram, ECG doesn't read hypokinesis. The artery involved would have to be the left anterior descending and some septal perforators from the location. Depending on clinical situation, you might need a coronary angiogram if interventional therapy is appropriate. You should be already on CAD treatment.