The influence of strut thickness and cell design on immediate apposition of drug-eluting stents assessed by optical coherence tomography

In-stent restenosis associated with stent malapposition: seven year optical coherence tomography findings

Stent thrombosis and in-stent restenosis remain significant issues in post-coronary angioplasty care despite advances in anti-platelet therapy and stent technology. Angiographic predictors of stent failure have been proposed, but its precise mechanism has been difficult to elucidate on conventional coronary angiography and intravascular ultrasound due to the low resolution of either approach. Optical coherence tomography (OCT) as a high-resolution intracoronary imaging modality has enabled more detailed insight into the interaction between implanted stent and underlying endothelium, the evolution of unstable plaque, and the pathogenesis of late lumen loss, affirming its place as an essential tool in the modern-day cardiac catheterisation laboratory. We present a case of in-stent restenosis seven years after bare-metal stent insertion, the mechanism of which was gross stent malapposition as clearly demonstrated on OCT examination.

Intracoronary thrombus formation after drug-eluting stents implantation: optical coherence tomographic study

BACKGROUND

Intracoronary thrombus formation after drug-eluting stent (DES) implantation is not sufficiently evaluated.

METHODS

Optical coherence tomography (OCT) was performed in 226 patients (total DES n = 244, sirolimus-eluting stent [SES] n = 95, paclitaxel-eluting stent [PES] n = 62, zotarolimus-eluting stent [ZES] n = 87) after implantation (mean 11 months, range 3-66 months). Using OCT, we investigated the incidence and determinants of intracoronary thrombus.

RESULTS

Intracoronary thrombus was detected in 35 (14%) cases (27 SES [28%], 7 PES [11%], and 1 ZES [1%], P < .001) and was associated with longer stent, smaller stent diameter, and stents at bifurcation lesions. More uncovered stent struts (26 +/- 23 vs 8 +/- 17, P < .001) and malapposed stent struts (6 +/- 14 vs 2 +/- 6, P < .001) were also associated with intracoronary thrombus. Multiple logistic regression analysis found the following determinants of intracoronary thrombus: stent length > or =28 mm (odds ratio [OR] 7.31, 95% CI 1.79-29.86, P = .01), stent diameter <3.0 mm (OR 4.38, 95% CI 1.38-13.97, P = .01), and > or =8 uncovered struts in each stent (OR 3.29, 95% CI 1.07-10.17, P = .04).

CONCLUSIONS

Length, size, and types of DES may be more important than clinical factors in intracoronary thrombus formation after DES implantations.

An optical coherence tomography study of a biodegradable vs. durable polymer-coated limus-eluting stent: a LEADERS trial sub-study

AIMS

Incomplete endothelialization has been found to be associated with late stent thrombosis, a rare but devastating phenomenon, more frequent after drug-eluting stent implantation. Optical coherence tomography (OCT) has 10 times greater resolution than intravascular ultrasound and thus appears to be a valuable modality for the assessment of stent strut coverage. The LEADERS trial was a multi-centre, randomized comparison of a biolimus-eluting stent (BES) with biodegradable polymer with a sirolimus-eluting stent (SES) using a durable polymer. This study sought to evaluate tissue coverage and apposition of stents using OCT in a group of patients from the randomized LEADERS trial.

METHODS AND RESULTS

Fifty-six consecutive patients underwent OCT during angiographic follow-up at 9 months. OCT images were acquired using a non-occlusive technique at a pullback speed of 3 mm/s. Data were analysed using a Bayesian hierarchical random-effects model, which accounted for the correlation of lesion characteristics within patients and implicitly assigned analytical weights to each lesion depending on the number of struts observed per lesion. Primary outcome was the difference in percentage of uncovered struts between BESs and SESs. Twenty patients were included in the analysis in the BES group (29 lesions with 4592 struts) and 26 patients in the SES group (35 lesions with 6476 struts). A total of 83 struts were uncovered in the BES group and 407 out of 6476 struts were uncovered in the SES group [weighted difference -1.4%, 95% confidence interval (CI) -3.7 to 0.0, P = 0.04]. Results were similar after adjustment for pre-procedure lesion length, reference vessel diameter, number of implanted study stents, and presence of stent overlap. There were three lesions in the BES group and 15 lesions in the SES group that had > or =5% of all struts uncovered (difference -33.1%, 95% CI -61.7 to -10.3, P < 0.01).

CONCLUSION

Strut coverage at an average follow-up of 9 months appears to be more complete in patients allocated to BESs when compared with SESs. The impact of this difference on clinical outcome and, in particular, on the risk of late stent thrombosis is yet to be determined.