Propensity and mechanisms of restenosis in different coronary stent designs (original) (raw)
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Late Loss in Lumen Diameter and Binary Restenosis for Drug-Eluting Stent Comparison
Circulation, 2005
Background-Published rates of coronary restenosis have fallen below 10% in drug-eluting stent trials. Early evaluations of new stents have used continuous end points that are presumed surrogates for restenosis, but the generalizability and power of such end points have not been examined systematically. Methods and Results-We examined the relationship between incremental changes in observed late loss in lumen diameter and the probability of restenosis using reported late loss from 22 published trials of various types of stents (bare-metal, drug-eluting, and small-vessel stents). Next, the power of late loss differences was compared with that of corresponding binary restenosis rates. The relationship between mean late loss and its SD was linear and did not vary with stent type (drug-eluting or bare-metal) or vessel diameter. At all levels of late loss examined (0 to 1 mm), incremental changes were associated with increasing restenosis risk (with an increasing magnitude of effect at higher levels of late loss). The power to detect a treatment effect was greater for late loss than for binary angiographic restenosis (Ն32% relative increase in power, Ն24% absolute increase for late loss between 0.2 and 0.6 mm).
Relationship of Late Loss in Lumen Diameter to Coronary Restenosis in Sirolimus-Eluting Stents
Circulation, 2005
Background-Observed rates of restenosis after drug-eluting stenting are low (Ͻ10%). Identification of a reliable and powerful angiographic end point will be useful in future trials. Methods and Results-Late loss (postprocedural minimum lumen diameter minus 8-month minimum lumen diameter) was measured in the angiographic cohorts of the SIRIUS (nϭ703) and E-SIRIUS (nϭ308) trials. Two techniques, the standard normal approximation and an optimized power transformation, were used to predict binary angiographic restenosis rates and compare them with observed restenosis rates. The mean in-stent late loss observed in the SIRIUS trial was 0.17Ϯ0.45 mm (sirolimus) versus 1.00Ϯ0.70 mm (control). If a normal distribution was assumed, late loss accurately estimated in-stent binary angiographic restenosis for the control arm (predicted 35.4% versus observed 35.4%) but underestimated it in the sirolimus arm (predicted 0.6% versus observed 3.2%). Power transformation improved the reliability of the estimate in the sirolimus arm (predicted 3.2% [CI 1.0% to 6.7%]) with similar improvements in the E-SIRIUS trial (predicted 4.0% [CI 1.2% to 7.0%] versus observed 3.9%). In the sirolimus-eluting stent arm, in-stent late loss correlated better with target-lesion revascularization than in-segment late loss (c-statisticϭ0.915 versus 0.665). Conclusions-Because distributions of late loss with a low mean are right-skewed, the use of a transformation improves the accuracy of predicting low binary restenosis rates. Late loss is monotonically correlated with the probability of restenosis and yields a more efficient estimate of the restenosis process in the era of lower binary restenosis rates. (Circulation. 2005;111:321-327.)
Effects of stent length and lesion length on coronary restenosis
The American Journal of Cardiology, 2004
The choice of drug-eluting versus bare metal stents is based on costs and expectations of restenosis and thrombosis risk. Approaches to stent placement vary from covering just the zone of maximal obstruction to stenting well beyond the lesion boundaries (normal-tonormal vessel). The independent effects of stented lesion length, nonstented lesion length, and excess stent length, on coronary restenosis have not been evaluated for bare metal or drug-eluting stents. We analyzed the angiographic follow-up cohort (1,181 patients) from 6 recent bare metal stent trials of de novo lesions in native coronary arteries. Stent length exceeded lesion length in 87% of lesions (mean lesion length 12.4 ؎ 6.3 mm, mean stent length 20.0 ؎ 7.9 mm, mean difference 7.6 ؎ 7.9 mm). At 6-to 9-month follow-up, the mean percent diameter stenosis was 39.1 ؎ 20.1%. In an adjusted multivariable model of percent diameter stenosis, each 10 mm of stented lesion length was associated with an absolute increase in percent diameter stenosis of 7.7% (p <0.0001), whereas each 10 mm of excess stent length independently increased percent diameter stenosis by 4.0% (p <0.0001) and increased target lesion revascularization at 9 months (odds ratio 1.12, 95% confidence interval 1.02 to 1.24). Significant nonstented lesion length was uncommon (12.5% of cases). In summary, stent length exceeded lesion length in most stented lesions, and the amount of excess stent length increased the risk of restenosis independent of the stented lesion length. This analysis supports a conservative approach of matching stent length to lesion length to reduce the risk of restenosis with bare metal stents. ᮊ2004 by
A stent is not just a stent: Stent construction and design do matter in its clinical performance
Singapore medical journal, 2004
The undisputed superiority of stents over conventional balloon angioplasty has resulted in a plethora of stents in clinical use. Recent data, however, have indicated not all stent models are the same. Nuances in stent design and construction have impacted significantly on the immediate and long-term clinical outcome. Among the stainless steel stents, those with multicellular or tubular designs have proven to be superior to coiled or hybrid stent models, and thin-strut stents perform better than thicker-strut stents. Coating stainless steel stents with gold, carbide, phosphorylcholine or heparin do not appear to confer any additional benefit, compared with bare metal stents. In contrast, randomised trials have demonstrated that drug-eluting stents coated with various anti-proliferative drugs, with or without a carrier polymer, afford unparalleled restenosis rates compared with non-drug-eluting stents. Drug-eluting stents, however, are expensive, and their long-term durability and saf...
Restenosis after coronary placement of various stent types
The American Journal of Cardiology, 2001
Coronary stent implantation is being performed in an increasing number of patients with a wide spectrum of clinical and lesion characteristics. A variety of stent designs are now available and continuous efforts are being made to improve the stent placement procedure. The objective of this study was to perform a comprehensive analysis of the relation between clinical, lesion, and procedural factors, and restenosis after intracoronary stenting in a large and unselected population of patients. A consecutive series of 4,510 patients with coronary stent placement was analyzed. Exclusion criteria were only a failed procedure and an adverse outcome within the first month after the intervention. Follow-up angiography was performed in 80% of patients at 6 months. Clinical, lesion, and procedural data from all 3,370 patients (4,229 stented lesions) with follow-up angiography were analyzed in a logistic regression model for restenosis (>50% diameter stenosis). Clinical factors contributed to the predictive power of the model much less than lesion and procedural factors. The strongest risk factor for restenosis was a small vessel size, with a 79% increase in the risk for a vessel of 2.7 mm versus a vessel of 3.4 mm in diameter. Stent design was the second strongest factor; the incidence of restenosis ranged from 20.0% to 50.3% depending on the stent type implanted. In conclusion, this study demonstrates the predominant role of lesion and procedural factors in determining the occurrence of restenosis after coronary stent placement. Among these factors, stent design appears to play a particularly important role in the hyperplastic response of the vessel wall.
Journal of the American …, 2003
Background-Increased thrombogenicity and smooth muscle cell proliferative response induced by the metal struts compromise the advantages of coronary stenting. The objective of this randomized, multicenter study was to assess whether a reduced strut thickness of coronary stents is associated with improved follow-up angiographic and clinical results. Methods and Results-A total of 651 patients with coronary lesions situated in native vessels Ͼ2.8 mm in diameter were randomly assigned to receive 1 of 2 commercially available stents of comparable design but different thickness: 326 patients to the thin-strut stent (strut thickness of 50 m) and 325 patients to the thick-strut stent (strut thickness of 140 m). The primary end point was the angiographic restenosis (Ն50% diameter stenosis at follow-up angiography). Secondary end points were the incidence of reinterventions due to restenosis-induced ischemia and the combined rate of death and myocardial infarctions at 1 year. The incidence of angiographic restenosis was 15.0% in the thin-strut group and 25.8% in the thick-strut group (relative risk, 0.58; 95% CI, 0.39 to 0.87; Pϭ0.003). Clinical restenosis was also significantly reduced, with a reintervention rate of 8.6% among thin-strut patients and 13.8% among thick-strut patients (relative risk, 0.62; 95% CI, 0.39 to 0.99; Pϭ0.03). No difference was observed in the combined 1-year rate of death and myocardial infarction. Conclusions-The use of a thinner-strut device is associated with a significant reduction of angiographic and clinical restenosis after coronary artery stenting. These findings may have relevant implications for the currently most widely used percutaneous coronary intervention. (Circulation. 2001;103:2816-2821.) Key Words: coronary disease Ⅲ restenosis Ⅲ stents Ⅲ trials C oronary stenting is an established form of treatment for the majority of patients with symptomatic coronary artery disease. 1-4 The main benefit of stenting compared with conventional percutaneous transluminal coronary angioplasty (PTCA) consists of the reduction of restenosis. In fact, the reduction of restenosis is exclusively the result of a bigger initial lumen achieved with stenting. This initial gain is more than sufficient to compensate for the greater neointima formation induced by the metal endoprosthesis. 5 Recent advances in stent design have generally improved the procedural success rate and short-term lumen gain. They may have a different impact on restenosis, however, as demonstrated by a series of recent studies on the relative efficacies of various stent designs. 6-9 Although it has been possible to differentiate between stents in terms of their long-term efficacy, the mechanisms underlying these differences have not yet been elucidated. Major efforts and resources are concentrated on strategies aiming at the preven
Journal of the American College of Cardiology, 2001
We sought to investigate the in vivo mechanical properties of a new self-expanding coronary stent (RADIUS) and, particularly, the subsequent vessel response over time. BACKGROUND Preclinical studies have suggested that self-expanding stents may produce less vessel wall injury at initial deployment, leading to larger follow-up lumens than with balloon-expandable stents. However, the influence of the chronic stimulus from self-expanding stents on the vessel wall remains unknown. METHODS Sixty-two patients were randomly assigned to either the RADIUS self-expanding stent group (n ϭ 32) or the Palmaz-Schatz balloon-expandable stent group (n ϭ 30). Intravascular ultrasound was performed after stent deployment and at six-month follow-up. RESULTS At follow-up, the RADIUS stents had increased 23.6% in overall volume, while the Palmaz-Schatz stents had remained unchanged. Due to the greater mean neointimal area (3.0 Ϯ 1.7 mm 2 vs. 1.9 Ϯ 1.2 mm 2 , p ϭ 0.02) in the RADIUS group, no significant difference in net late lumen loss was observed between the two groups. On the other hand, analysis at the peristent margins demonstrated that mean late loss was significantly smaller in the RADIUS group than it was in the Palmaz-Schatz group (0.1 Ϯ 2.1 mm 2 vs. 1.9 Ϯ 2.4 mm 2 , p ϭ 0.02). CONCLUSIONS Serial volumetric IVUS revealed that the RADIUS stents continued to enlarge during the follow-up period. In this stent implantation protocol, this expansion was accompanied by a greater amount of neointima than the Palmaz-Schatz stents, resulting in similar late lumen loss in both configurations. In the peristent margins, however, late lumen loss was minimized with the RADIUS stents.