Reversible? It depends. Is the ischemia reverisble or irreversible? Was it detected on a nuclear stress test? Assume it's reversible as seen in a nuclear stress test. Such things seen on a perfusion scan are often referred to as apical defects. That said, along with other indications, I might suggest a clinical correlation via an angiogram or ccta. The consequences could not be determined without a cath or ccta.
Variable. If the left anterior discerning artery was small and blocked, a person may do fine. If the artery is large this may be a warning to get it fixed. There are other variations, but that is one of the medical surgical decision trees.
Old or new. If old, may be result of prior limited heart attack and collaterals if new, may be preliminary to heart attack and should be investigated and the "culprit" lesion treated by pci or surgery, .
Depends. I suppose that was a conclusion from a nuclear stress test? 1) it maybe an artifact, so called false positive test. 2) if its real, a lot depends on presence and severely of your symptoms.
Depends. Small ischemia at the apex could be caused by a variety of different lesions in the blood vessels of the heart. The next step in defining your consequences is to define the anatomy of your heart vessels with dye and determine if and where there is blockage. The specific location and length of blockage (s) will define your consequences.