Randomised comparison of Micro Stent I with Palmaz-Schatz stent placement for the elective treatment of short coronary stenoses

Impact of stent design on clinical outcome after coronary stent implantation

Coronary stents have considerably improved both immediate and late results after coronary angioplasty, by limiting elastic recoil and vascular remodeling, but their use does not eliminate restenosis, caused mainly by neointimal hyperplasia. Stents are now implanted in over 70% of percutaneous coronary interventions. More than 50 coronary stents have already been approved in Europe and over 20 stents are commercially available in the USA, raising the question: which device is best suitable for which lesion? Several in vitro experiments revealed significant differences in expansion characteristics of coronary stents, related to the strut design and metallic composition. Animal studies were performed to determine the influence of stent design on the patterns and extent of neointimal hyperplasia. However, the clinical results of randomized trials comparing stent types in humans have not always reflected laboratory findings. This article is a critical overview of experimental and clinical data concerning the impact of stent design on the early and late clinical outcome after coronary stent implantation.

Robustness of late lumen loss in discriminating drug-eluting stents across variable observational and randomized trials

BACKGROUND

Binary angiographic and clinical restenosis rates can vary widely between clinical studies, even for the same stent, influenced heavily by case-mix covariates that differ among observational and randomized trials intended to assess a given stent system. We hypothesized that mean in-stent late loss might be a more stable estimator of restenosis propensity across such studies.

METHODS AND RESULTS

In 46 trials of drug-eluting and bare-metal stenting, increasing mean late loss was associated with higher target lesion revascularization (TLR) rates (P<0.001). When the class of bare-metal stents was compared with the class of effective drug-eluting stents, late loss was more discriminating than TLR as measured by the high intraclass correlation coefficient (rho) (late loss, rho=0.71 versus TLR, rho=0.22; 95% CI of difference=0.33, 0.65). When the individual drug-eluting stents and bare-metal stents were compared, late loss was a better discriminator than TLR (0.68 versus 0.19; 95% CI of difference=0.24, 0.60). Greater adjustments of study covariates are needed to stabilize assessments of TLR compared with late loss because of greater influence of reference vessel diameter on TLR than on in-stent late loss. Optimization of late loss with the use of a novel method of standardization according to diabetes prevalence and mean lesion length resulted in minor adjustments in late loss (<0.08 mm for 90% of reported trials) and an ordered array of mean late loss values for the stent systems studied.

CONCLUSIONS

Late loss is more reliable than restenosis rates for discriminating restenosis propensity between new drug-eluting stent platforms across studies and might be the optimum end point for evaluating drug-eluting stents in early, nonrandomized studies.

Prospective randomized comparison of early and late results of 4 different stent designs

BACKGROUND

Late results of interventional procedures using coronary stents are largely determined by the rate of restenosis. So far, few data are available addressing the effect of stent design on this crucial variable and on early and late adverse events after stent implantation.

METHODS

From 1996 through 1998, a total of 965 lesions in 925 patients with coronary artery disease were randomized to treatment with 1 of 4 different stent designs (Micro stent II [M] AVE, Düsseldorf, Germany; Sito [S] Sitomed, Rangendingen, Germany; Pura Vario [PV], Devon, Hamburg, Germany; Inflow [ID] Inflow Dynamics, München, Germany). The primary end point of the study was the degree of diameter stenosis measured by quantitative coronary angiography 6 months after stent implantation.

RESULTS

Diameter stenosis at 6 months follow-up was not different in the 4 study arms (M 40.3 +/- 24.1, S 42.8 +/- 27.0, PV 42.6 +/- 26.9 and ID 42.3 +/- 26.8, P =.7). No significant differences could be detected in net lumen gain and late lumen loss, resulting in comparable restenosis rates (>or=50% diameter stenosis) at follow-up (M 26.0%, S 30.5%, PV 31.3%, and ID 28.7%, P =.7). Early adverse events like stent loss, stent thrombosis, periinterventional acute myocardial infarctions and emergency coronary artery bypass graft also showed no significant differences. Multivariate regression analyses revealed reference vessel diameter <3.0 mm, overall stented length, a history of bypass grafting, localization of the target lesion in the left anterior descending coronary artery, type C lesions, dissection before stent implantation, and diabetes mellitus to be independent predictors for restenosis.

CONCLUSION

Stent design does not have significant influence on development of restenosis. Adverse event rates were similar with all stent types used in this trial.

Low restenosis rate of the NIR coronary stent: results of the Danish multicenter stent study (DANSTENT)--a randomized trial comparing a first-generation stent with a second-generation stent

BACKGROUND

Larger studies evaluating the angiographic results of second-generation stents are scarce. The objectives of this study were to assess current standards of angiographic and clinical outcomes after implantation of the second-generation stainless steel stent, NIR (Medinol Ltd, Tel Aviv, Israel), and to compare the outcomes with those of the first-generation Palmaz-Schatz (PS) stent (Johnson & Johnson, Warren, NJ).

METHODS

Patients having coronary artery lesions that could be covered by a stent of 15 mm in length were randomly assigned to receive the NIR or the PS. Procedural success, 6-month angiographic findings, and 1-year clinical outcomes were determined.

RESULTS

In 424 patients included in the study, the overall procedural success rate was high (NIR 98%, PS 99%, P =.90). Follow-up angiography was conducted in 91% of the patients. The overall rate of angiographic restenosis was low in both groups (NIR 9.9%, PS 12.6%, P =.35). We found a low restenosis rate in vessels with a minimal lumen diameter >3.1 mm after the procedure, particularly in the NIR group (<6%). The rate of target lesion revascularization after 1 year did not differ (NIR 12%, PS 10%, P =.47).

CONCLUSIONS

The angiographic and clinical outcomes after implantation of the second-generation stainless steel stent were not significantly better than those of the first-generation stent. The low restenosis rates, particularly in patients with the largest minimal lumen diameters after stent implantation, warrants circumspection when planning the evaluation of newer stent technologies that aim to further reduce coronary restenosis.

Restenosis rates with flexible GFX stents (REFLEX): clinical and angiographic results

The objective of this prospective, multicenter, observational trial was to evaluate the procedural results and longterm outcomes of the flexible AVE GFX coronary stent in native coronary lesions. The trial included 137 consecutive patients (111 [81%] men, age 63.1 +/- 9.2 years) with one vessel disease (n = 76 [55.5%]), two vessel disease (n = 31 [22.6%]), and three vessel disease (n = 30 [21.9%]) with ischemia secondary to a significant denovo lesion (diameter > or = 3 mm, length < or = 18 mm) in a native coronary artery. Stent deployment was successful in 97.8% (134/137) of patients. Angiographic follow-up at 6.1 +/- 1.2 months was available in 111 (82.8%) of 134 patients. All angiographic images were analyzed by an independent core lab. The primary end point was the binary restenosis rate. In-hospital major cardiac events occurred in 3.7%. No postdischarge major adverse cardiac events occurred, except for one abrupt closure (0.7%). Angiographic restenosis was documented in 22 (19.8%) of 111 patients. The GFX stent is easy to handle with high success and low restenosis rates in patients with simple lesions in native coronary arteries and, thus, compares favorably with other sophisticated stents.

Feasibility, safety, cost-effectiveness and 1 year follow-up of coronary stenting without predilation: a matched comparison with the standard approach

BACKGROUND

We evaluated the feasibility, safety, procedural cost-effectiveness, radiation dose and time and 1-year target vessel revascularization rate of direct unprotected mounted stenting without previous balloon dilatation (DS) in native coronary artery lesions.

METHODS

DS was attempted in 119 patients; 39 had a recent myocardial infarction, 62 had unstable angina, and 18 had stable angina. The clinical follow-up was obtained at 14+/-5 months (range 6 to 24 months). These results were compared with those for a consecutive group of 160 patients matched for type and length of lesions and who had a stent only if the post-balloon residual stenosis was >30%.

RESULTS

The feasibility of DS was 112/119 (94%). The number of inflations, the length of the stent/length of the lesion ratio, the time and the dose of radiation were dramatically lower in the DS group (P<0.001). DS conferred a slight reduction in procedure-related cost [$820+/-157 for DS vs. 894+/-427 for standard dilatation (SD) per patient]. The 1-year target vessel revascularization rate was similar in both groups [nine (8%) for DS vs. 17 (11%) patients for SD, ns].

CONCLUSIONS

DS is feasible and safe in selected coronary lesions. This method provides a low rate of repeat revascularization and reduces the time and the dose of radiation compared with the standard approach.