I have a nuclear stress test coming. if it's negative can i be sure i dont have clogged arteries? also does it show ef better than echo

Test value: The nuclear study gives information about perfusion(blood delivery)to various parts of the heart. You may still have blockages but your body can compensate by growing collateral vessels so that a single blockage may not affect overall blood supply to an area. The study is also helpful in giving ejection fraction information but usually correlates fairly to echo but may be more precise