The study included 51 patients who were referred for coronary catheter angiography after coronary CTA. The following patients were excluded: patients with irregular heart rates, patients with previous coronary bypass grafts and those with coronary stents. Patients with a resting heart rate above 75 bpm and a medical contraindication for beta blockers administration are excluded. History of contrast allergy, renal impairment and severe chest conditions are exclusion criteria. The coronary angiographic CT studies were performed using a Somatom Definition 鈥渄ual source鈥?64 CT scanner (Siemens, medical scientific Germany). The catheter coronary angiographic studies were performed via femoral arterial puncture. The standard 15-segment model of the coronary tree was employed. Segments were classified as being normal, atherosclerotic (with no significant stenosis), stenotic (>50%luminal narrowing), occlusive or non evaluable. The results of CT angiography are compared with the gold standard catheter angiography.
Results: Overall sensitivity, specificity, PPV and NPV were 93%, 92%, 92%and 93%, respectively with an overall diagnostic accuracy of 93%. The sensitivity is 84%to detect stenoses 60-70%in, 85%sensitivity with 70-80%stenoses, 96%with 80-90%stenoses and 96%with stenoses more than 90%.