Treatment of In-Stent restenosis using a stent with non-polymer-based paclitaxel elution

Current understanding of coronary in-stent restenosis. Pathophysiology, clinical presentation, diagnostic work-up, and management

In-stent restenosis is the limiting entity following coronary stent implantation. It is associated with significant morbidity and cost and thus represents a major clinical and economical problem. Worldwide, approximately 250 000 in-stent restenotic lesions per year have to be dealt with. The pathophysiology of instent restenosis is multifactorial and comprises inflammation, smooth muscle cell migration and proliferation and extracellular matrix formation, all mediated by distinct molecular pathways. Instent restenosis has been recognised as very difficult to manage, with a repeat restenosis rate of 50% regardless of the mechanical angioplasty device used. Much more favourable results were reported for the adjunctive irradiation of the in-stent restenotic lesion, with a consistent reduction of the incidence of repeat in-stent restenosis by 50%. Data from the first clinical trials on drug-eluting stents for the treatment of in-stent restenosis have shown very much promise yielding this strategy likely to become the treatment of choice. This review outlines the histological and molecular findings of the pathophysiology, the epidemiology, the predictors and the diagnostic work-up of in-stent restenosis and puts emphasis on the various treatment options for its prevention and therapy.

Use of Taxus polymer-coated paclitaxel-eluting stents for treatment of in-stent restenosis in real world patients: Results of clinical and angiographic follow-up at six months in a single-center registry

OBJECTIVE

To evaluate the safety and efficacy of Taxus paclitaxel-eluting stents in a real world group of unselected patients with coronary in-stent restenosis (ISR) lesions.

METHODS

This is a prospective single-center registry of a consecutive series of 94 patients with 104 ISR lesions, without previous brachytherapy, over a period of 1 year. Quantitative coronary angiographic analyses were performed at baseline and at 6-month angiographic follow-up. Clinical follow-up were obtained at 6 months.

RESULTS

Pre-intervention mean reference vessel diameter was 2.62 +/- 0.50 mm and mean lesion length was 13.95 +/- 6.78 mm. Baseline ISR patterns were mostly either Type I focal (32.7%) or Type II diffuse intrastent (48.1%). At 6-month angiographic follow-up, the in-stent and in-segment binary restenosis was 3.8% (4/105) and 7.6% (8/105) respectively, and the in-stent and in-segment late loss was 0.30 +/- 0.50 mm and 0.57 +/- 0.54 mm, respectively. Seven of these eight restenosed lesions had a diffuse or proliferative ISR pattern prior to intervention. Lesions that restenosed had longer mean stent length per lesion (37.3 mm vs. 22.5 mm in nonrestenosed group; P = 0.001) and more likely to have had a pattern of total occlusion pre-intervention (25.0% vs. 3.1% in nonrestenosed group; P = 0.046). At 6-month clinical follow-up, the MACE rate was 8.5% and target lesion revascularization rate was 7.4%. There was no death but subacute stent thrombosis occurred in 1 patient (1.1%) at 3 days after intervention.

CONCLUSIONS

Paclitaxel-eluting Taxus stent for the treatment of ISR effectively suppresses recurrent neointimal proliferation, and was safe and efficacious at 6-month follow-up.

Contemporary use of drug-eluting stents

Since the era of balloon angioplasty, stents have been a revolutionary advance in the treatment of severe coronary artery disease. However, one of the major limitations is in-stent restenosis. Although brachytherapy was found to be an effective treatment, the goal remains to develop a kind of stent that will not restenose. The emergence of drug-eluting stents provided a novel solution for the reduction of restenosis. The currently approved indication for drug-eluting stents by the US Food and Drug Administration is for discrete, de novo lesions in native vessels with reference vessel diameters of 2.5 to 3.5 mm. However, in the worldwide daily practice, there have been numerous off-label uses of drug-eluting stents, and their long-term follow-up and experience in more complex lesions are accumulating. This article reviews the current off-label uses of drug-eluting stents. The majority of the supporting data are from registry and observational studies, yet many studies are limited by small sample sizes. Therefore, large, prospective, randomized, double-blind, and controlled trials are definitely warranted to further support current practice. Nevertheless, the "real world" unrestricted uses of drug-eluting stents seem to be the current trend in the interventional field.

Drug-coated Stents

Since its introduction in 1977, the success of percutaneous interventional cardiology has been limited by the occurrence of restenosis. Drug-eluting stents, particularly sirolimus- and paclitaxel-coated stents, have been shown in randomized controlled trials to dramatically reduce restenosis in single, de novo, native coronary arteries. Over the last 2 years, investigators have reported that these stents can also reduce restenosis in more complex patient situations such as in diabetics, during acute coronary syndromes, in long atherosclerotic lesions and small arteries, and even after in-stent restenosis. These outcomes increase the clinical value of this technology to "real world" practice. This article reviews the current state of our knowledge regarding drug-eluting stents and identifies areas for further research.