In-stent Lumen Research Articles

Primary Stenting of Totally Occluded Native Coronary Arteries II (PRISON II)

Sirolimus-eluting stents markedly reduce the risk of restenosis compared with bare metal stents. However, it is not known whether there are differences in effectiveness between bare metal and sirolimus-eluting stents in patients with total coronary occlusions. In a prospective, randomized, single-blind, 2-center trial, we enrolled 200 patients with total coronary occlusions: Half (n = 100) were randomly assigned to receive bare metal BxVelocity stents and half (n = 100) to receive sirolimus-eluting Cypher stents. The primary end point was angiographic binary in-segment restenosis rate at 6-month follow-up. Secondary end points were a composite of major adverse cardiac events, target vessel failure, binary in-stent restenosis rate, in-stent and in-segment minimal lumen diameter, percent diameter stenosis, and late luminal loss at 6-month follow-up. The sirolimus stent group showed a significantly lower in-stent binary restenosis rate of 7% compared with 36% in the bare metal stent group (P < 0.001). The in-segment binary restenosis rate was 11% in the group receiving a sirolimus stent versus 41% in the bare metal stent group (P < 0.0001), resulting in a target lesion revascularization rate of 4% in the sirolimus group versus 19% in the bare metal group (P < 0.001). Patients who received the drug-eluting stent also had significantly lower rates of target vessel revascularization, target vessel failure, and all major adverse cardiac events. In patients with total coronary occlusions, use of the sirolimus-eluting stents are superior to the bare metal stents with significant reduction in angiographic binary restenosis, resulting in significantly less need for target lesion and target vessel revascularization.

Comparison of drug eluting stents with bare metal stents in daily practice for bifurcation lesions in Chinese patients

Recently, numerous randomized and controlled trials have demonstrated great advantages of drug eluting stents (DES) with respect to significant reduction of restenosis and recurrence of symptoms and improvement of clinical outcomes after percutaneous coronary intervention (PCI). Little is known about the comparative effects between DES and bare metal stents (BMS) for bifurcation angioplasty in the Chinese population. We compared the inpatient and 7-month follow-up outcomes between DES and BMS for the treatment of bifurcation lesions. From April 2004 to October 2005, 291 Chinese patients [85.9% male, mean age (57.8 +/- 10.4) years] underwent DES (387 lesions) and/or BMS (297 lesions) implantation for bifurcation lesions. Clinical and angiographic follow-up was performed at 7 months. Compared with BMS group, patients in DES group had significantly lower rates of restenosis at main branch (9.5% vs 28.7%, P < 0.001) or side branch (14.5% vs 37.0%, P < 0.001) and major adverse cardiac events (MACE) (14.0% vs 26.3%, P = 0.000). The occurrence rate of late in-stent thrombosis did not differ between the two groups in both main (0.8% vs 0, P = 0.224) and side branches (1.4% vs 0, P = 0.198). Target lesion revascularization (TLR) was less frequent in DES group for main branch (8.3% vs 21.3%, P < 0.001) and for side branch (7.6% vs 23.5%, P < 0.001). Multivariate regression analysis revealed that total stent length (OR = 1.029, P = 0.01), postprocedural in-stent minimum lumen diameter (OR = 0.476, P = 0.03) and stent type (OR = 3.988, P = 0.0001) were independent predictors of TLR for main branch. Prior history of coronary intervention (OR = 2.424, P = 0.041), angulated lesion (OR = 2.337, P = 0.033), postdilation (OR = 0.267, P = 0.035) and stent type (DES vs BMS, OR = 5.459, P = 0.000) were independent predictors of TLR for side branch. The implantation of DES may be associated with greater reduction of restenosis and TLR than BMS in bifurcations angioplasty.

Comparison Between Theoretical and Actual Intracoronary Stent Dimensions in Non-Complex Lesions

The minimum in-stent lumen diameter is a predictor of restenosis. Stent dimensions provided by manufacturers are derived from in vitro tests. The aim of this study was to compare actual stent dimensions obtained by angiography and intracoronary ultrasound with dimensions that would be expected theoretically for a given inflation pressure in a cohort of 100 non-complex lesions suitable for direct stenting. Significant differences were found between the theoretical diameters and those observed by angiography and ultrasound. The actual-to-theoretical diameter ratio was 0.83 (0.09) when measured using angiography and 0.78 (0.10), using intravascular ultrasound. In lesions without severe calcification, stent dimensions were significantly smaller than indicated by the manufacturer. Nominal figures should not be used as reference values for stent implantation.

Evaluation of various image reconstruction parameters in lower extremity stents using multidetector-row CT angiography: initial findings

Image quality, visible lumen and patency of lower limb stents was assessed by multidetector-row computed tomography (MDCT) angiography using various reconstruction parameters and the results compared with conventional angiography. Fourteen patients (25 stents) were evaluated. From MDCT datasets, axial and coronal oblique reformations were reconstructed using differing reconstruction parameters (slice thickness, kernel, views). Artifacts and image quality were assessed using a five-degree scale (1=excellent, 5=poor). Visible stent diameter was measured. Stenosis severity was compared with calibrated catheter angiography. The image quality of medium and sharp image kernels were good/fair (1.9-2.4), while smooth kernel provided only acceptable/poor image quality (3.9-4.4). Coronal oblique images were rated superior to assess in-stent lumen rather than axial. Using medium and sharp kernels, the visible stent lumen was significantly greater than using smooth kernel (P<0.001). thirteen out of fourteen patients (24/25 stents) were correctly classified as patent. In one patient, in-stent stenosis (> or =50%) was falsely diagnosed using CT angiography (CTA) with smooth kernel and was, therefore, rated as false positive. Coronal oblique views, as well as medium and sharp kernels, have shown the best results regarding image quality to assess stent patency in the lower limb. Therefore, MDCT could be a valuable non-invasive modality for stent imaging in the peripheral vasculature.

Direct stenting of de novo coronary stenoses with tacrolimus-eluting versus carbon-coated carbostents. The randomized JUPITER II trial.

Drug-eluting stents are being increasingly used for the treatment of de novo coronary lesions. This trial compared the performance of tacrolimus-eluting stents (TES) with that of equivalent carbon-coated stents (CCS). The JUPITER II trial enrolled 332 patients (mean age = 64 years, 75% men) with de novo coronary stenoses. Patients were randomly assigned to TES versus CCS and underwent repeat coronary angiography at 6 months. The primary study endpoint was in-stent and in-segment late lumen loss (LLL). The main secondary endpoints included binary restenosis, and rates of major adverse clinical events (MACE), including death, myocardial infarction, target lesion revascularisation and stent thrombosis at 1, 6, and 12 months of follow-up. The procedure was successful in 99.4% of patients in both groups. There was no procedural death, 1 cardiac death at 2 months, and 1 acute and 2 subacute CCS thromboses. Angiographic follow-ups were available in 94.4% and 95.1% of patients assigned to TES and CCS, respectively. The mean in-segment and in-stent LLL was 0.42+/-0.46 mm and 0.65+/-0.47 mm, respectively, in the TES, versus 0.48+/-0.52 mm and 0.66+/-0.53 mm, respectively, in the CCS group (ns). The 12-month cumulative MACE rate was 19.5% in the CCS versus 16.1% in the TES group (ns). Both stents showed high safety, with no stent thrombosis in the TES group. No difference was observed in 6-month angiographic results and 12-month MACE rates between TES and CCS.

Multidetector CT for Visualization of Coronary Stents

Whereas the clinical diagnosis of in-stent thrombosis is straightforward, that of in-stent restenosis remains a problem, because although many patients experience chest pain after coronary stent placement, that symptom is secondary to ischemia in only a few. The use of a noninvasive technique to identify such patients for early invasive intervention versus more conservative management is thus highly desirable. Multidetector computed tomography (CT) performed with 16-section scanners recently emerged as such a technique and has overtaken modalities such as electron-beam CT and magnetic resonance imaging as an alternative to conventional angiography for the assessment of in-stent restenosis. The improved hardware design of the current 64-section CT scanners allows even better delineation of stent struts and lumen. The more reliable criterion of direct lumen visualization thus may be substituted for the presence of distal runoff, which lacks specificity for a determination of in-stent patency because of the possibility of collateral pathways. However, the capability to accurately visualize the in-stent lumen depends partly on knowledge of the causes of artifacts and how they can be compensated for with postprocessing and proper image display settings. In addition, an understanding of the major stent placement techniques used in the treatment of lesions at arterial bifurcations is helpful.

Impact of calcified lesion on the intimal hyperplasia after implantation of drug eluting stent: an intravascular ultrasound study

To investigate the impact of calcified lesion on the intimal hyperplasia after implantation of drug eluting stent. Ninety-nine rapamycin-eluting stents were implanted into the left anterior descending branches of coronary artery of 97 patients with 99 lesions. Eight months later intravascular ultrasound (IVUS) was used to examine the cross section area (CSA) of the external elastic membrane (EEM) at the stent inlet and at the stent outlet, in-stent CSA, CSA of the lumen, area of neo-intima (in-stent area minus lumen CSA), the maximum and minimum diameters of stent, and symmetry index of stent (minimal diameter of stent/maximum diameter of stent). Forty-one lesions were calcified and 58 non-calcified. Fourteen of the 99 lesions in the 97 patients developed intimal hyperplasia. The inlet stent CSA of the calcified group was (7.30 +/- 1.94) mm(2), similar to that of the non-calcified group (6.58 +/- 1.96) mm(2); the outlet CSA of the calcified group was (6.74 +/- 2.02) mm(2), similar to that of the non-calcified group (6.14 +/- 1.82) mm(2). The minimum stent CSA of the calcified group was (4.97 +/- 1.51) mm(2), significantly smaller than that of the non-calcified group (6.10 +/- 1.87) mm(2) (P < 0.05), the symmetry index of the calcified group was 0.92 +/- 0.07, significantly lower than that of the non-calcified group (0.92 +/- 0.07, P < 0.05), and the intimal area of the calcified group was (0.02 +/- 0.20) mm(2), significantly smaller than that of the non-calcified group (0.53 +/- 1.50) mm(2) (P < 0.05). Drug eluting stent implantation in the patients with calcified lesions has a less stent CSA and poor symmetry, and less intimal hyperplasia compared with those in the non-calcified lesions.

A Prospective Registry to Evaluate Sirolimus-Eluting Stents Implanted at Coronary Bifurcation Lesions Using the “Crush Technique”

The "crush technique" has been proposed as an alternative approach to treat bifurcation lesions because of its predictability and high procedural success rate. However, few data are available regarding its safety and long-term efficacy. We report the long-term clinical outcomes of patients with coronary bifurcation lesions treated with sirolimus-eluting stents using the crush technique. From April 2003 to May 2004, 120 patients with coronary bifurcation lesions were treated with sirolimus-eluting stents using the crush technique. Six months of clinical follow-up was completed in 95.8% of patients. Mean patient age was 64 years; 36% had diabetes mellitus, and the left anterior descending artery/diagonal was the most frequent bifurcation location (69%). Final kissing balloon inflation was performed in 87.5% of patients. Compared with the main vessel, side branch lesions were shorter, with a smaller reference diameter and final in-stent minimum lumen diameter. Procedural success was achieved in 97.5%. At 30 days of follow-up, 1 patient had died of noncardiac causes and 2 patients (1.7%) had subacute stent thrombosis. At 6 months of follow-up, target lesion revascularization was required in 13 patients (11.3%), all of whom had focal restenosis predominantly at the side branch ostium. In conclusion, the crush technique with final kissing balloon inflation can be safely used by experienced operators to treat highly complex bifurcation lesions with sirolimus-eluting stents. The safety profile of this technique is similar to that of other bifurcation stenting techniques reported thus far. Nonetheless, despite the excellent patency rates of the main vessel, the need for revascularization at the ostium of the side branch was not fully eliminated.

Comparisons of the Short-Term Angiographic Outcomes of Cypher and Taxus Stents Implanted in the Same Patient

Background and Objectives:Drug-eluting stents (DES) have been shown to substantially reduce both angiographic and clinical restenosis. Cypher (sirolimus-eluting stent, Cordis, Johnson and Johnson, Florida, USA) and Taxus (paclitaxel-eluting stent, Boston Scientific, Boston, USA) are the two most widely used DESs, and they both have distinct pharmacological properties and release kinetics. It has been not studied whether these two DESs show different angiographic outcomes when they are simultaneously implanted in the same patient. Subjects and Methods:We retrospectively analyzed the angiographic findings of the short-term follow-up in 34 patients (average age: 63 year old, 9 women) in whom both Cypher and Taxus stents were implanted at the same time for the treatment of obstructive coronary lesion. Results:There was no significant difference in the basal angiographic characteristics of the lesions that had two stents deployed in terms of the AHA/ACC classification, reference diameter, the percent diameter stenosis and minimal luminal diameter. The post-procedure results were similar between the two stents. At 6 months follow-up, the Cypher stent displayed significantly less in-stent lumen loss compared with the Taxus stent (0.16±0.04 mm vs 0.27±0.04 mm; respectively, p=0.040) and a smaller percent diameter stenosis (15.9±1.3% vs 19.9±2.2%, respectively, p=0.049). Conclusion:The Cypher stent showed significantly less luminal loss during short term follow-up compared with the Taxus stent when implanted in the same patient. This result suggests that in a given individual patient, the Cypher stent induces less neointimal proliferation than does the Taxus stent. (Korean Circulation J 2006;36:600-604)

Effect of Stent Oversizing on In-Stent Stenosis and Lumen Size in Normal Porcine Veins

To present an in vivo evaluation of the effects of stent oversizing on in-stent stenosis and on actual lumen size in normal veins. Twelve self-expanding stents were implanted in the common iliac veins of 6 minipigs, which were divided in 2 groups for follow-up at 1 and 3 months, respectively. Oversizing ranged from 119.5% to 216% of the original vessel diameter. Intravascular ultrasound (IVUS) was used to measure vessel areas at the stent edges and midpoint. In-stent stenosis and decrease in actual lumen size were evaluated with IVUS immediately after implantation and during follow-up. There was a very strong positive linear regression between stent oversizing and in-stent stenosis in the 1-month model (r=0.947, p=0.004), in the 3-month model (r=0.931, p=0.007), and in the sum of these 2 groups (r=0.83, p<0.001). Regarding the change in actual lumen size, we found a strong negative linear regression with stent oversizing in the 1-month (r=-0.754, p=0.083) and the 3-month (r=-0.562, p=0.246) groups, but these did not attain statistical significance. However, a strong correlation between stent oversizing and a decrease in lumen size in all samples proved to be statistically significant (r=0.619, p=0.032). Stent oversizing was strongly correlated with increased in-stent stenosis and decreased actual lumen size at follow-up in normal non-stenotic porcine veins.

Noninvasive assessment of coronary stents in patients by 16-slice computed tomography

Background The usefulness of thin-slice multi-detector computed tomography (MDCT) has been highly expected to assess the lumens of coronary artery stents. We evaluated the usefulness of 16-slice MDCT to assess the in-stent lumen after coronary artery stenting. Methods In 42 consecutive patients after coronary artery stenting, retrospective ECG-gated CT-angiography using 16-slice MDCT (0.5-s rotation time, 16 × 0.625-mm detector collimation) was performed. The qualitative assessability of the lumens of 61 coronary stents (14 different types) by MDCT and the reasons for non-assessability were investigated. Furthermore, the evaluation of in-stent restenosis in 21 assessable stents of 16 patients, inluding quantitative density analysis by MDCT, was performed and the results were compared with those of conventional coronary angiography (CAG). Results Of 61 stents, 42 (68.9%) were assessable. The assessability of diameter ≥ 3.5-mm stents made of stainless steel or cobalt was high (88.6%, 31/35), that of 3.0-mm stents was low (57.9%, 11/19) and all 2.5-mm stents were non-assessable due to partial volume effects and metal artifacts of stents. The lumens of stents made of tantalum were totally obscured and the metal artifacts of Bestent2 (gold markers) and S670 were severer than others. All non-assessable stents due to banding artifact and calcification were implanted in segment #1–3 and #6, respectively. In comparison to CAG, MDCT correctly detected the 5 in-stent restenoses and identified absence of restenoses was influenced strongly by the stent strut. Conclusion Despite some limitations, 16-slice MSCT is sufficiently useful for assessment of various coronary stents in patients and can detect in-stent restenoses of assessable stents with high accuracy in comparison to CAG.

Effect of Lumen Narrowing Within Coronary Stents on Proximal and Distal Vessel Segments Following Bare Metal Stent Implantation

Adjacent reference vessel response to smaller lumens at stented segments was examined with 3-dimensional intravascular ultrasound analysis. In 128 patients after bare metal stent implantation, minimal lumen area (MLA) within the stent and average lumen area at distal/proximal adjacent reference segments (5 mm) were obtained at baseline and follow-up. In the smaller in-stent MLA group (MLA <3 mm2), lumen area decreased significantly at the distal edge compared with the larger in-stent MLA group (MLA > or =3 mm2), although no significant difference was seen at the proximal edge. In-stent lumen patency may influence vascular responses at adjacent reference segments after bare metal stent implantation.

Four-Year Angiographic and Intravascular Ultrasound Follow-Up of Patients Treated With Sirolimus-Eluting Stents

Despite the proven superiority of sirolimus-eluting stents (SESs) compared with bare stents in the first year after implantation, long-term outcomes of patients treated with these novel devices remain unknown. Our goal was to evaluate the clinical, angiographic, and intravascular ultrasound (IVUS) outcomes of patients treated with SESs 4 years after implantation. The study included 30 patients treated with sirolimus-eluting Bx Velocity stenting (slow release [SR; n=15] and fast release [FR; n=15]). Twenty-six patients underwent 4-year angiographic and IVUS follow-up and had matched assessments at all time points (index and 4-, 12-, 24-, and 48-month follow-up). One death occurred during the study period in a patient with a patent SES. There were no target-vessel revascularizations or thromboses between 2- and 4-year follow-up examinations. There was no stent thrombosis, target-lesion revascularization, death, or myocardial infarction in the SR group up to 4 years. Cumulative event-free survival rate was 87% for the total population (80% in the FR group and 93% in the SR group). In-stent late loss was slightly greater in the FR group (0.41+/-0.49 mm) than the SR group (0.09+/-0.23) after 4 years. One patient in the FR group had a 52% in-stent restenosis lesion. Percent neointimal hyperplasia volume, as detected by IVUS, remained minimal after 4 years (FR=9.1% and SR=5.7%). This study confirms the longevity of the optimal outcomes observed in patients treated with sirolimus-eluting Bx Velocity stents 4 years after implantation. In-stent lumen dimensions remained essentially unchanged at 4-year follow-up, particularly in the population treated with the currently available SES (SR formulation).

Sirolimus-Eluting versus Bare Nitinol Stent for Obstructive Superficial Femoral Artery Disease: The SIROCCO II Trial

To investigate further the safety and efficacy of the sirolimus-eluting S. M.A.R.T. Nitinol Self-expanding Stent by comparison with a bare stent in superficial femoral artery (SFA) obstructions. This randomized, double-blind study involved 57 patients (29 in the sirolimus-eluting stent group and 28 in the bare stent group) with chronic limb ischemia and SFA occlusions (66.7%) or stenoses (average lesion length, 81.5 mm +/- 41.2). Stent implantation followed standard interventional techniques and a maximum of two stents could be implanted. The primary endpoint was the in-stent mean lumen diameter at 6 months as determined by quantitative angiography. Both stent types were effective in revascularizing the diseased SFA and allowing sustained patency for at least 6 months. There was no statistically significant difference between treatment groups in the in-stent mean lumen diameter at 6 months (4.94 mm +/- 0.69 and 4.76 mm +/- 0.54 mm for sirolimus-eluting and bare stent groups, respectively; P = .31). Although the diameter of the target lesion tended to be larger and percent stenosis tended to be lower with the sirolimus-eluting stent, there were no statistically significant differences between treatments in terms of any of the variables. The mean late loss values were 0.38 mm +/- 0.64 and 0.68 mm +/- 0.97 for the sirolimus-eluting stent group and the bare stent group, respectively (P = .20). The binary restenosis rates, with a cutoff of 50% at 6 months, were zero in the sirolimus-eluting stent group and 7.7% in the bare stent group (P = .49). Clinical outcomes matched angiographic outcomes with improvements in ankle-brachial index and symptoms of claudication. There was no significant difference between treatments in terms of adverse events. Although there is a trend for greater efficacy in the sirolimus-eluting stent group, there were no statistically significant differences in any of the variables.

Sirolimus-Eluting Stents versus the Superficial Femoral Artery: Second Round

RESTENOSIS remains a major limitation of femoropopliteal interventions, despite technologic advances in numerous endovascular strategies. Percutaneous transluminal angioplasty has been only modestly successful in the treatment of atherosclerotic disease of the superficial femoral artery (SFA), with 1-year patency rates of 41%–85% depending on lesion length, presence of diabetes, and distal runoff (1–6). Vascular stents are effective in rescuing suboptimal angioplasty results. However, the impact of femoropopliteal stent placement is still compromised by neointimal hyperplasia, and multiple studies have shown no improvement in lasting patency after primary stent placement compared with angioplasty alone (1,7–9). Newer generations of nitinol self-expanding stents appear to have a positive impact on femoropopliteal patency, but this has not been confirmed in a randomized setting (10–12). Drug-eluting stents have revolutionized the treatment of coronary artery disease. In the first human application of this breakthrough technology, minimal in-stent angiographic restenosis was observed in 28 patients 2 years after implantation of sirolimus-eluting stents in coronary arteries (13). These results were confirmed in a randomized study that included 238 patients (14). At 6-month angiographic follow-up, none of the patients had in-stent restenosis in the sirolimus-eluting stent group, compared with 26.6% in the bare stent group. With use of the same technology, inhibition of in-stent restenosis was also reproduced in a study that included 850 patients with complex coronary lesions consisting of a high percentage of diabetic patients and patients with longer lesions (15). At 8-month angiographic follow-up, the in-stent restenosis rates were 3.2% versus 35.4% in the sirolimus and bare stent groups, respectively. It was hypothesized that these impressive results could be obtained in the femoropopliteal segment by applying the same technology. The first human evaluation of drugeluting stents for the treatment of obstructive SFA disease (average length of 85 mm 57) included 36 patients randomized to receive treatment with bare versus sirolimus-eluting S.M.A.R.T. stents (Cordis, Warren, NJ) (16). The 6-month angiographic follow-up revealed a larger in-stent mean lumen diameter of 4.95 mm in the sirolimus group, versus 4.31 mm in the bare stent group (P .05). The lower 6-month binary restenosis rate (0 vs 23.5%) and the lower mean in-stent percent diameter stenosis (22.6% vs 30.9%) observed in the sirolimus-eluting stent group were not significant as a result of the small sample size. It was later learned that a subgroup of five patients who had received a slow-release drug coating within the sirolimus-eluting stent group had less restenosis than patients in the fast-eluting sirolimus and bare stent groups at 9 and 18-month duplex follow-ups. The SIROCCO I study showed the feasibility and safety of the use of a drugeluting self-expandable stent platform, but it also suggested that slow-eluting stents could reduce SFA restenosis. Based on these results, the SIROCCO II extension trial, presented in this issue of JVIR, was conducted in 57 additional patients randomized to receive treatment with the slow-release form of sirolimus-eluting and bare S.M.A.R.T. stents (17). Because stent fractures were detected in six patients who had received at least three overlapping stents in the SIROCCO I study (16), a maximum of two stents per patient was allowed in the SIROCCO II study (17) to treat lesions with an average length of 81.5 mm 41.2. Although there was a trend toward better performance of sirolimus-eluting stents, the 6-month angiographic follow-up revealed no significant difference between treatment groups in any of the variables: the in-stent mean lumen diameter values were 4.94 mm 0.69 versus 4.76 mm 0.54, the binary restenosis rates were zero versus 7.7%, and the late loss values were 0.038 0.64 versus 0.68 0.97 in the sirolimus and bare stent groups, respectively. In addition, 18-month duplex follow-up data presented at the 2004 Annual Meeting of the Cardiovascular and Interventional Radiology Society of Europe revealed a 20.7% binary restenosis rate in the sirolimus group (six stenoses and no occlusions in 29 paFrom the Department of Radiology, Centre Hospitalier de l’Universite de Montreal, Notre-Dame Hospital, 1560 Sherbrooke East, Montreal, Quebec, Canada H2L 4M1. Address correspondence to V.L.O.; E-mail: voliva@sympatico.ca

Artifact-Free Coronary Magnetic Resonance Angiography and Coronary Vessel Wall Imaging in the Presence of a New, Metallic, Coronary Magnetic Resonance Imaging Stent

Coronary in-stent restenosis cannot be directly assessed by magnetic resonance angiography (MRA) because of the local signal void of currently used stainless steel stents. The aim of this study was to investigate the potential of a new, dedicated, coronary MR imaging (MRI) stent for artifact-free, coronary MRA and in-stent lumen and vessel wall visualization. Fifteen prototype stents were deployed in coronary arteries of 15 healthy swine and investigated with a double-oblique, navigator-gated, free-breathing, T2-prepared, 3D cartesian gradient-echo sequence; a T2-prepared, 3D spiral gradient-echo sequence; and a T2-prepared, 3D steady-state, free-precession coronary MRA sequence. Furthermore, black-blood vessel wall imaging by a dual-inversion-recovery, turbo spin-echo sequence was performed. Artifacts of the stented vessel segment and signal intensities of the coronary vessel lumen inside and outside the stent were assessed. With all investigated sequences, the vessel lumen and wall could be visualized without artifacts, including the stented vessel segment. No signal intensity alterations inside the stent when compared with the vessel lumen outside the stent were found. The new, coronary MRI stent allows for completely artifact-free coronary MRA and vessel wall imaging.

ISR II study: A long-term evaluation of sirolimus-eluting stent in the treatment of patients with in-stent restenotic native coronary artery lesions

The aim of this pilot study was to determine the safety and long-term efficacy of treating intrastent restenosis (ISR) with the slow-release sirolimus-eluting stent Bx Velocity (Cypher stent) without intravascular ultrasound (IVUS) guidance. Of patients who received a bare metal stent implantation and presented an ISR, 30-80% of the patients will develop a second restenosis within the stent, at the stent edges or both. To date, intravascular brachytherapy using beta- and gamma-radiation has been the only effective treatment for ISR. Twenty-three patients with ISR and evidence of ischemia were treated with Cypher stent. Clinical information was collected 1, 8, 12, and 24 months after stent implantation. During the first 8 months of the study, in-stent lumen diameter remained essentially unchanged from postprocedure in 80% of the case. The target lesion repeat revascularization (TLR) was 17%, of which 50% were oculostenotic reflexes. Only one patient presented a restenosis greater than 70%. During the 2-year study period, the TLR rate was 17%; the major adverse coronary event rate was 26%, and the non-Q-wave myocardial infarction (MI) rate was 9%. There were no reports of death, coronary artery bypass grafting, or Q-wave MI during the study. This study demonstrates the feasibility of using sirolimus-eluting stents without IVUS guidance for the treatment of ISR, providing long-term stability of immediate results.

Coronary artery stent patency assessed with in-stent contrast enhancement measured at multi-detector row CT angiography: initial experience.

The authors investigated the contrast enhancement characteristics of the coronary artery stent lumen to assess patency and then evaluated the accuracy of computed tomographic (CT) measurement of the in-stent luminal diameter. Nineteen patients (16 men and three women; mean age, 58.7 years) with 26 stents underwent cardiac-gated CT angiography with a 16-detector row scanner 1-3 weeks after stent placement. CT images depicted the lumina of 20 stents in 14 patients. CT attenuation measured in the treated lumen was higher than, and correlated highly (r >/= 0.87) with, attenuation in the proximal and distal untreated lumen. Estimated values for in-stent luminal diameter were lower with CT than with conventional angiography (P <.001), and the mean error (16.1%) that resulted from estimation based on sharp-kernel CT images was significantly smaller than that (27.3%) from estimation based on medium-smooth-kernel CT images (P <.001). Visualization of the in-stent lumen at CT angiography with a 16-detector row scanner allows assessment of coronary artery stent patency on the basis of measured contrast enhancement.

Oral rapamycin to prevent human coronary stent restenosis: A pilot study

Background Recent human trials with rapamycin-eluting stents have shown very low restenosis rates. However, the high costs of these devices preclude their use in routine angioplasty, especially when considering multiple stenting. We evaluated whether orally administered rapamycin inhibits in-stent neointimal growth in patients with unstable angina. Methods We enrolled 15 patients successfully treated with the implantation of a single stent in a single de novo lesion in native coronary arteries. Correct stent expansion and apposition were corroborated with intravascular ultrasound scanning in all patients. Patients received aspirin, clopidogrel, and atorvastatin for 6 months. Rapamycin was administered in a loading dose of 5 mg, followed by 2 mg/day for 4 weeks. Results The reference diameter was 3.4 ± 0.4 mm, lesion length was 11.2 ± 2 mm, lesion type B1 was 36%, and lesion type B2 was 64%. After the procedure, in-stent minimal lumen diameter and diameter stenosis (DS) were 3.3 ± 0.4 mm and 0.3% ± 7.5%, respectively. At 10 days, plasma levels of rapamycin were 7.95 ± 2.6 ng/mL. At 6 months, angiographic determinations demonstrated an in-stent minimal lumen diameter of 2 ± 1 mm, an in-stent DS of 41.3% ± 28.0%, and an in-stent late loss of 1.4 ± 1.1 mm. Binary restenosis (>50% DS) was present in 6 of 15 patients (40%). Target lesion revascularization (coronary artery bypass grafting) was performed in 2 of 15 patients (13.3%). There were no serious adverse events during the 6-month period of follow-up, but 1 patient had severe heartburn caused by esophagitis, and another patient had herpes zoster at the end of the protocol. Conclusions Oral rapamycin was well tolerated, but did not suppress in-stent neointimal growth in this small group of patients.

The Canadian study of the sirolimus-eluting stent in the treatment of patients with long de novo lesions in small native coronary arteries (C-SIRIUS)

ObjectivesWe assessed the safety and effectiveness of the sirolimus-eluting stent (SES) in treating single de novo long lesions in small native coronary arteries compared to an identical bare metal stent (BMS). BackgroundThe SES was previously demonstrated to reduce restenosis significantly. However, patients with long lesions in small vessels have not been well studied and may define a group at very high risk. MethodsThe Canadian Study of the Sirolimus-Eluting Stent in the Treatment of Patients With Long De Novo Lesions in Small Native Coronary Arteries (C-SIRIUS) was a multicenter, randomized, double-blind trial comparing SES versus identical BMS. The primary end point was in-stent minimal lumen diameter (MLD) at eight months. Secondary end points included angiographic restenosis at 8 months, target lesion revascularization (TLR), and major adverse cardiac events (MACE) at 270 days. ResultsA total of 100 patients were enrolled at eight Canadian sites. The in-stent MLD at eight months was 2.46 ± 0.37 mm in the SES compared with 1.49 ± 0.75 mm in the BMS (a 65% increase, p < 0.001). Angiographic restenosis occurred in 1 of 44 SES patients (2.3%, with no in-stent restenosis) and in 23 of 44 BMS patients (52.3%, p < 0.001). At 270 days, there were two clinically driven TLRs in the SES (4%) and nine in the BMS (18%, p = 0.05). The Kaplan-Meier estimate of freedom from MACE at 270 days was 96.0% for SES patients and 81.7% for BMS patients (p = 0.029). ConclusionsPatients with long lesions in small vessels are at very high risk of restenosis. In these patients, the SES dramatically reduces the risk of restenosis at eight months, translating into an excellent clinical outcome at nine months.