OBJECTIVETo evaluate the diagnostic accuracy of 320-slice CT coronary angiography (CTA) in the evaluation of in-stent restenosis (ISR, ≥50% luminal narrowing) in comparison with quantitative coronary angiography (CAG).

METHODSA total of 69 patients with previous stent implantation who underwent both CTA and CAG were prospectively included. We assessed diagnostic valve for ISR with CTA in comparison with CAG.

RESULTSA total of 110 stents were implanted in these patients.CAG identified 14 ISR. CTA correctly identified 13 ISR and misdiagnosed 5 ISR in stents without ISR. Besides, 6 stents could not be evaluated by CTA due to unsatisfied image quality. Accordingly, sensitivity, specificity, positive and negative predictive value of CTA for diagnosing ISR were 93%, 89%, 54% and 99%, respectively. The image quality of CTA was significantly better in larger stents (percentages of good and moderate stent image of ≥3.0 mm and <3.0 mm: 56% vs. 27%, 25% vs. 49%) and which was linked with better diagnostic coincidence rate (95% vs. 78%) for larger stents. The image quality of CTA was significantly better in stents with thinner stent strut thickness (percentages of poor CTA stent image quality of stent strut thickness<140 µm and ≥140 µm: 12% vs. 45%, P<0.01) and which was associated with better diagnostic coincidence rate for stents with thinner stent strut thickness (94% vs. 76%, P<0.05). The image quality of CTA was also significantly better in single stent (percentages of poor CTA stent image quality of single stent vs. overlap and dedicated stent: 17% vs. 36%, P<0.05). However, heart rate (≥65 beats/min vs. <65 beats/min) during CTA acquisition was not associated with image quality and the diagnostic coincidence rate (all P>0.05).

CONCLUSIONSOur results indicate that 320-slice CTA allows accurate noninvasive assessment of significant in-stent restenosis in selected patients. Stents with a large diameter and thin struts are associated with better image quality and higher diagnostic accuracy.