What is the significance of anterolateral ischemia?

Location. Anterolateral is just the description of the location - in front and to the side - where ischemia is seen in a myocardial perfusion scan. The ischemia - lack of blood flow and therefore oxygen to part of the heart is what is significant! anytime there is insufficient or no blood flow to part of the heart it is critical to restore this flow as soon as possible.
See a cardiologist. Anteriorlateral ischemia stronly suggests that you have more demand for oxgenated blood to the front and side of your heart than you coronary arteries can supply. An ecg, possible stress test and maybe a cardiac catheterization would likely be recommended. I recommend you see your primary care provider and then a cardiologist.