Objective: To 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).
Methods: A 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.
Results: A 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).
Conclusions: Our 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.