Beemer,
Sorry to hear about your heart attack. Let me answer the question I think you are asking.....how can I have a negative stress test and still have a heart attack. Stress tests are good at determining long term prognosis and evaluating the progression of coronary disease. It is not good at determining who is at greatest risk for a heart attack. Heart attacks usual result from a crack or fissure in one your heart arteries that leads to the formation of a clot or thrombus. Stress tests are not good at or intended to diagnose valnerable plaque. We still don't have a test that can do that very well. high sensitivity CRP is a marker of systemic inflammation and can hint toward patients at great risk, but we are still looking for the magic bullet.
To answer your question directly,
1. Breast tissue or surface tissue can sometimes interfere with interpretation of a nuclear scan and shows up as a fixed region that appears to have decreased blood flow. The key is that this region is the same in both resting and stress images. Ischemia (not enough blood flow) is determined by a new defect on the stress image that isn't present for the rest image.
2. This is the same as above, except now it is the diaphragm or breathing muscle that is interfering with test interpretation.
I hope this helps answer your question and thanks for posting.