What does a false positive result pertaining to a heart stress test means:?

Had a heart stress test done which showed a medium sized anteroapical wall perfusion defect, moderate in intensity at the apex, full reversible. The angiagram showed 90 % blockage in the circumflex which the exam looked like I had sufficient detours to reach the destination when the heart is at rest but when the heart pumps harder and when the vessels are tight no blood travels back to the heart and you have angina. Can someone explain all of this as I don't fully understand all of the above. Thanks J.J.