I am a smoker. i have low bp and my weight is 50kg. i experience chest discomfort whenever i stand or walk. can a multislice coronary ct angio 256 miss a blockage even if my calcium score is 0?

Absolutely, Yet....: Mscct scanners/operators vary widely in quality, few as good as former imatron e-speed but purchased for ↓ed cost/promotion. Coronary angio far clearer than any of the ct scanners. Soft-plaque is problem; calcification=old stable plaque & not-visible, 0 score, if not enough. Far better option: get&optimize NMR particle test ldl& large hdl, also get hba1c ≤5.0%+stop smok, try ntg spray; ? Not hrt?

2 questions: Coronary calcium screening and ccta angio provide different but related info. A coronary calcium score of 0 means there is no evidence of cholesterol in the heart blood vessels that the body has calcified; it would not determine anything about the presence of noncalcified, possibly obstructive disease. Ccta looks for obstruction. If is good quality study and normal, then no blockage.

Less likely: If your calcium score is 0 and no plaque is seen, the chance of it being missed is minimal, unless the ct was not read properly.