Noninvasive evaluation of coronary artery stents patency after PTCA: role of Multislice Computed Tomography.

Purpose: Restenosis of a coronary artery treated with stent implantation is a well-known process that can compromise over time the success of a coronary angioplasty and, accordingly, treated patients must undergo periodic controls. We have recently witnessed a shift towards a greater use of Multi-slice CT (msCT) in the study of coronary disease without its precise indications and limits having yet been underlined. The purpose of our study is to assess the role of msCT in the follow-up of patients treated with coronary angioplasty.
Materials and Methods: Forty-eight patients, for a total of 72 lesions, who underwent treatment with a slotted tube stent implant, had an msCT examination 1 week before scheduled coronary angiography, and the results were compared. 34 stents/72 (47.2%) were inserted on the left anterior descending; 21/72 (29.2%) on the right coronary; 17/72 (23.6%) on the circumflex artery or obtuse marginal branches.
Results: The observation of the opacification of the vessel located distally to treated segments allowed us to assess the patency of all stents. Coronary angiography identified a significant intrastent restenosis or a stent occlusion in 12 of the 72 stents analysed (16.7%). msCT enabled easier visualization of the lumen of the treated artery and its differentiation from the stent struts in the ones located on the left anterior descending artery than those on the circumflex (28 stents out of 34 [82.4%] vs 13/17 [76.5%]; p<0.05), and on the right coronary artery, which were difficult to evaluate (11/21 [52.4%]). We were also able to visualize the lumen of 14/15 stents with a calibre over 3.5 mm [93.3%] vs 35/45 stent with dimensions between 3.1 e 3.4 mm [77.8%], and only 4 stents <3 mm/12 [33.3%]. On multivariate analysis, the characteristics that were significantly and independently associated with accurate visualization of the lumen of a stented vessel were location on the proximal anterior descending artery (OR 4.03 [IC 95%: from 2.34 to 8.05]; p<0.0001) and stent size of >3.5 mm (OR 2.97 [IC 95%: from 1.67 to 4.86]; p<0.01).
Conclusions: The msCT technology available at present makes the study of smaller stents and those positioned on the right coronary artery and circumflex rather complex; on the other hand msCT appears a promising study method for stents greater then 3.5 mm and for those positioned on the proximal segment of the left anterior descending artery.