Plaque Shift Research Articles

Edge Effect From Drug-Eluting Stents as Assessed With Serial Intravascular Ultrasound

Several studies have demonstrated effective reduction of intimal hyperplasia within a drug-eluting stent (DES) when compared with a bare metal stent (BMS), thereby resulting in a lower incidence of target lesion revascularization.1–3 Restenosis at the stent edges, however, is not appreciably reduced by DES. Thus, to understand stent edge effect in DES, it is important to improve the efficacy of this technology. The concern that stent edge effects alter intimal hyperplasia in the stent but not at the edges has existed for many years, and often is described as the “candy wrapper phenomenon.” This phenomenon was first described in radioactive stents4,5 and is due to local inhibition of intimal growth and endothelial healing6 only within the stent. Many DES trials, therefore, sought to better understand the edge effect using intravascular ultrasound (IVUS) to assess the vessel response post stent implantation. Many studies have documented DES edge effect in older- and newer-generation DES. One challenge facing IVUS studies that assess DES edge effect is a high degree of patient-to-patient variability, along with potential variability among the different DES types. Because of these variables and the relatively small size of most sequential IVUS studies, there is no general consensus regarding stent edge effect in DES. We therefore reviewed the literature to find common findings and tendency. This review focused on 4 DES types approved by the United States Food and Drug Administration: the Cypher sirolimus-eluting stent (SES) (Cordis), the Taxus paclitaxel-eluting stent (PES) (Boston Scientific), the Endeavor zotarolimus-eluting stent (ZES) (Medtronic CardioVascular Inc.), and the XIENCE V everolimus-eluting stent (EES) (Abbott Vascular). ### Mechanical Edge Effect Post Stent Implantation Edge stenosis can occur from several different mechanisms: a vascular response from peri-stent vascular injury, plaque shift, and thrombus or hematoma formation post stent implantation. Before discussing DES and the impact of adding …

Anatomic and Functional Evaluation of Bifurcation Lesions Undergoing Percutaneous Coronary Intervention

We sought to investigate the mechanism of geometric changes after main branch (MB) stent implantation and to identify the predictors of functionally significant "jailed" side branch (SB) lesions. Seventy-seven patients with bifurcation lesions were prospectively enrolled from 8 centers. MB intravascular ultrasound was performed before and after MB stent implantation, and fractional flow reserve was measured in the jailed SB. The vessel volume index of both the proximal and distal MB was increased after stent implantation. The plaque volume index decreased in the proximal MB (9.1+/-3.0 to 8.4+/-2.4 mm(3)/mm, P=0.001), implicating plaque shift, but not in the distal MB (5.4+/-1.8 to 5.3+/-1.7 mm(3)/mm, P=0.227), implicating carina shifting to account for the change in vessel size (N=56). The mean SB fractional flow reserve was 0.71+/-0.20 (N=68) and 43% of the lesions were functionally significant. Binary logistic-regression analysis revealed that preintervention % diameter stenosis of the SB (odds ratio=1.05; 95% CI, 1.01 to 1.09) and the MB minimum lumen diameter located distal to the SB ostium (odds ratio=3.86; 95% CI, 1.03 to 14.43) were independent predictors of functionally significant SB jailing. In patients with > or =75% stenosis and Thrombolysis In Myocardial Infarction grade 3 flow in the SB, no difference in post-stent angiographic and intravascular ultrasound parameters was found between SB lesions with and without functional significance. Both plaque shift from the MB and carina shift contribute to the creation/aggravation of an SB ostial lesion after MB stent implantation. Anatomic evaluation does not reliably predict the functional significance of a jailed SB stenosis.

Percutaneous Revascularization Is the Preferred Strategy for Patients With Significant Left Main Coronary Stenosis

In the early 1970s, coronary artery bypass graft (CABG) was found to improve late survival in comparison to medical therapy in patients with significant left main stenosis.1–3 Once CABG became the standard of care for left main disease, a distinction between “protected”—by at least 1 patent bypass graft to the left coronary artery—and “unprotected left main (UPLM)”— no patent bypass graft to the left coronary artery—was made. In the 1980s, early attempts at balloon angioplasty of UPLM stenoses were associated with poor early outcomes because of coronary dissection, abrupt closure, and restenosis. Mortality rates as high as 30% at 1 year were reported.4–6 In the 1990s, bare metal stents were introduced and soon used to treat UPLM disease. Several small registries found a low rate of procedural complications, but repeat revascularization rates of 20% to 30% because of restenosis were considered unacceptable.7–12 Early bare metal stent registries for UPLM also found high mortality rates, particularly in high-risk patients, such as patients with acute coronary syndromes and poor left ventricular function. Importantly, high-risk subgroups often presented with late sudden death after stenting.11,13 In the early 2000s, the introduction of drug-eluting stents (DES), with the promise of vastly reduced rates of restenosis,14–17 raised the possibility of improved late outcomes in this challenging patient group. Response by Smith p 1033 Clinical outcomes after treatment of UPLM disease with either the sirolimus-eluting stent or the paclitaxel-eluting stent from >20 small registries have been published. Results reported in these registries vary widely.18–40 As depicted in Table 1, cardiac mortality between 6 and 12 months after the procedure ranges from 0% to 11%. Target lesion revascularization (TLR) or target vessel revascularization (TVR) rates range from 2% to 38%. This wide variation in clinical outcome appears largely because of variation …

Arterial Puncture Closure Using a Clip Device After Transpopliteal Retrograde Approach for Recanalization of the Superficial Femoral Artery

To report the safety and efficacy of a clip device to close retrograde popliteal artery puncture sites used in recanalization of the superficial femoral artery (SFA). From January 2005 to March 2007, 28 patients (20 men; mean age 66+/-10 years) with stable chronic peripheral artery disease were treated for chronic total SFA occlusion. All patients received aspirin and clopidogrel and were heparinized during the procedure. After failed antegrade recanalization, the SFA was revascularized via a retrograde transpopliteal access. The StarClose Vascular System was used to seal the popliteal artery puncture site. All (100%) interventions were finished successfully, and hemostasis was secured with the StarClose device in all cases. There was 1 (3.6%) major complication with the StarClose system: a transient popliteal artery occlusion induced by plaque shift during sheath removal, which was corrected with balloon angioplasty via the femoral access. Three (10.8%) small hematomas (<5 cm) occurred at the puncture site without causing significant patient discomfort. In this small experience, the StarClose Vascular Closure System appeared to be an effective and safe sealing device after percutaneous transpopliteal interventions. Plaque shifting leading to stenosis or occlusion at the puncture site can occur.

Stent treatment of coronary artery bifurcation lesions

In percutaneous coronary interventions (PCIs), the treatment of bifurcation lesions is a challenge to the interventional cardiologist. PCI operators, in general, use the term coronary artery bifurcation (from latin furca = fork, branch): (i) when a coronary artery divides into two equally important branches or (ii) when a main branch gives away a side branch, which is large enough to be of haemodynamic significance, whereas when a large coronary artery gives away a small, haemodynamically unimportant side branch, the term bifurcation is less used. There is no consensus on when to use the term bifurcation lesion. Some PCI operators use this term for any lesion in or near a bifurcation, regardless they might be able to successfully stent the lesion using one wire and one stent only, whereas others reserve the term bifurcation lesion for complex lesions requiring two wires and intervention of both distal branches. The risk of PCI in different anatomical subsets has been identified in the American College of Cardiology/American Heart Association Guidelines since many years.1 However, lesion classifications based on severity of characteristics proposed in the past have been principally altered by the present PCI techniques. A number of well-known technical and clinical problems are associated with bifurcation PCI, dependent on the anatomy, the lesions, and on the technique used. Important concerns are (i) plaque shift causing flow problems, (ii) wire trapping and subsequent need of wire replacement, (iii) stent deformation, (iv) stent overlap and large metal burden in the arteries, (v) incomplete lesion coverage, (vi) subacute stent thrombosis, and (vii) restenosis. To overcome some of these problems, several specially designed bifurcation stent devices have been constructed. However, none of these have—so far—been tested in randomized comparisons with conventional stents. An interesting bifurcation device principle is a self-expandable nitinol device (DEVAX AXXESS), which when deployed … *Corresponding author. Tel: +45 35453693; fax: +45 35452705. E-mail address : erikjoergensen{at}rh.hosp.dk

&lt;b&gt;Poststenting Axial Redistribution of Atherosclerotic Plaque Into the Reference Segments and Lumen Reduction at the Stent Edge&lt;/b&gt;

Lumen enlargement during coronary stenting results from vessel expansion and axial redistribution of atheromatous plaque along the stented segment and proximal and distal reference segments. Plaque burden predicts stenosis at the stent edge. The aim of this study was to investigate the fate of shifted plaque with special reference to whether or not plaque shift (PSh) correlates with late lumen reduction. This is a prospective study conducted on 54 consecutive patients who underwent bare metal stenting. In all stent edges (108 edges), PSh volume was measured as postintervention plaque-media volume (PMV) minus preintervention PMV. Changes in lumen volume (DeltaLV), vessel volume (DeltaVV), and PMV (DeltaPMV) were measured by serial intravascular ultrasound (IVUS) examination. After stenting, PSh was detected in 81.5% of proximal edges versus 72.2% of distal edges (P = 0.36). It correlated significantly with DeltaVV (r = 0.34, P = 0.002), and inversely with DeltaLV (r = 0.32, P = 0.003). However, at 6-month follow-up, it did not correlate with DeltaLV (r = -0.03, P = 0.8), DeltaVV (r = 0.1, P = 0.6), or DeltaPMV (r = 0.1, P = 0.4). Furthermore, DeltaLV correlated more strongly with DeltaVV (r = 0.62, P < 0.00001) than with DeltaPMV (r = -0.39, P = 0.001). By multivariate analysis, PSh area was an independent predictor of the postintervention change in lumen area (partial eta squared 0.21, P = 0.01), but not the follow-up change. Two patients (3.7%) developed proximal edge stenosis with no evident PSh after stenting. Thus, axial redistribution of atheromatous plaque into the reference segments was frequently encountered after stenting. Although PSh correlated with the immediate reduction in stent edge lumen volume, it did not correlate with the late lumen reduction.

Effectiveness of the Stent Pull-Back Technique for Nonaorto Ostial Coronary Narrowings

Coronary stenting of nonaorto ostial coronary lesions is challenging because of plaque shift into the main vessel, triggering the use of additional stents. Furthermore, inappropriate coverage of the ostium of the side branch increases the risk of restenosis and target vessel revascularization (TVR). To improve the treatment of nonaorto ostial coronary lesions with a novel interventional technique, we tested the hypothesis that inflating a balloon in the main vessel before stenting the side branch (stent pull-back technique) will limit plaque shifting and reduce the use of additional stents. In addition, proper coverage of the side branch ostium may also reduce 8-month TVR. A case-control design with 100 consecutive patients who underwent drug-eluting stent placement was performed; 55 patients were treated with the stent pull-back technique and 45 patients with a conventional stent technique. Procedural success was 100% for the 2 techniques. The use of additional stents was reduced in the stent pull-back group compared with the conventional stent group (2% vs 18%, p = 0.007). A tendency toward lower ostial miss was also observed in the stent pull-back group (4% vs 13%, p = 0.11). The incidence of in-hospital and 30-day cardiac events was similar between the 2 groups. TVR was lower in the stent pull-back group compared with the conventional group (5% vs 20%; p = 0.03). In conclusion, the stent pull-back technique improves the percutaneous treatment of nonaorto ostial coronary lesions. The technique is associated with a lower use of additional stents and improved clinical outcome, reducing TVR at 8 months of follow-up.

Simultaneous kissing drug‐eluting stent technique for percutaneous treatment of bifurcation lesions in large‐size vessels

Treatment of bifurcation lesions is associated with high procedural complications and restenosis rate due to plaque shift, suboptimal angiographic results, difficulty in crossing the stent struts, and incomplete coverage of the side-branch ostium. The simultaneous kissing stent (SKS) technique involves two stents, one in main vessel (MV) and one in the side branch (SB) with overlapping stents in the MV proximally, extending proximally the carina of bifurcation. We analyzed our first 200 consecutive patients (202 lesions) who underwent SKS technique for true bifurcation lesions using sirolimus eluting stents, with a minimum follow-up of 6 months. Procedural success was 100% for MV and 99% for SB using SKS technique, with clinical success rate of 97%. In-hospital and 30-day major adverse cardiac events were 3% and 5%, respectively, with a procedure time of 36 +/- 14 min. At mean follow-up of 9 +/- 2 months, the incidence of target lesion revascularization was 4% in the entire group. Therefore, SKS technique using sirolimus-eluting stents may become an effective treatment strategy for large-size bifurcation lesions. However, in order to establish its superiority, SKS technique needs to be compared in a randomized manner with conventional stent techniques.

New Approaches to Ostial and Bifurcation Lesions

Percutaneous coronary intervention of bifurcation lesions is associated with lower procedural success rates, and an increased subsequent rate of major adverse cardiac events and restenosis. Currently, an array of stenting possibilities suggests a rational approach to treat various bifurcation lesions with appropriate techniques. This is however seldom the case. The main problems of treating bifurcation lesions remain plaque shift leading to (threatened) side branch occlusion, and either too much or insufficient side branch ostial stent coverage predisposing to impaired side branch access or restenosis, respectively. This paper reviews the available technologies and their relative merits.

Comparison of Cutting Balloon vs Stenting Alone in Small Branch Ostial Lesions of Native Coronary Arteries.

Angioplasty of small vessels is associated with a higher rate of restenosis, even in the ostium. The present study compared the acute, late results of cutting balloon vs those of stenting alone in small branch ostial lesions of native coronary arteries and the effect on the parent vessel. The study group comprised 61 patients with successful angioplasty of smaller branch ostial lesions in native coronary arteries. The reference vessel diameter was between 2.5 and 3.0 mm. Patients were divided into 2 groups: group I (cutting balloon, n=30) and group II (stenting alone, n=31). After intervention, patients in group II achieved significant acute lumen gain, larger minimal lumen diameter (MLD) and less diameter stenosis. At 3-month follow-up, the MLD and diameter stenosis of the 2 groups were almost identical; however, late loss was lower in group I. At the 6-month follow up, the cumulative restenosis rate was 41% (11/27) in group I compared with 63% (19/31) in group II (p=0.05), and the target lesion revascularization was also lower in the cutting balloon group [29% (8/27) vs 53% (16/30) p=0.05]. In group 1, the MLD of the parent vessel did not change before, after cutting balloon or at follow-up. In contrast, there were significant reductions in parent vessel MLD following stenting alone and at follow-up. Plaque shift did not occur in the cutting balloon group. Cutting balloon angioplasty is a feasible approach for the treatment of small branch ostial lesions and does not cause significant narrowing of the parent vessel.

Intravascular ultrasonic comparisons of mechanisms of vasodilatation of cutting balloon angioplasty versus conventional balloon angioplasty

Intimal hyperplasia after balloon dilatation may be related to the severity of vascular injury, and cutting balloon angioplasty (CBA) may reduce vascular injury. The present study investigated the mechanism of vasodilation by CBA. Intravascular ultrasound examination was performed before and after intervention in 40 lesions treated with CBA and in 25 lesions treated with conventional balloon angioplasty. Intravascular ultrasound measurements included the vessel area, luminal area, and plaque area. Vessel expansion was evaluated as the ratio of the postprocedural vessel area to that before intervention. The vessel area was 13.9 ± 3.2 and 14.8 ± 3.2 mm 2 after CBA versus conventional angioplasty, respectively, whereas the luminal area was 5.5 ± 1.2 versus 5.7 ± 1.2 mm 2 and the plaque area was 8.5 ± 2.7 versus 9.1 ± 2.2 mm 2, respectively. The vessel area was smaller and the plaque area significantly smaller after CBA. Vessel expansion accounted for 45% of luminal enlargement, and plaque compression or shift accounted for 55% after CBA. After conventional angioplasty, vessel expansion accounted for 67%, and plaque compression or shift for 33% of luminal enlargement. The vessel expansion ratio was significantly smaller after CBA than after conventional angioplasty (1.05 vs 1.22, p <0.05). These findings suggest that the predominant mechanism of dilatation after CBA is plaque compression or shift rather than vessel expansion, unlike conventional angioplasty.

Cutting balloon limits plaque shift in bifurcation lesions

Cutting balloon limits plaque shift in bifurcation lesions

Predictors of Side Branch Occlusion Immediately after Coronary Stenting: an Intravascular Ultrasound Study

Background and Objectives:Previous studies have indicated that side branch occlusion (SBO) remains a significant problem in coronary bifurcation lesions during percutaneous intervention. Subjects and Methods: To evaluate the predictors of SBO by intravascular ultrasound (IVUS), 35 patients (28 males, mean age 56± 11 years) were studied at their left anterior descending artery (LAD)-diagonal branch (DB) bifurcation lesions, prior to coronary intervention for the measurement of the following plaque characteristics:total plaque area (PA), PA of the branch-side semicircle, % area stenosis (%AS) of the LAD, the presence of bull’s eye in the DB, the diameter of the vessel and the ostial lumen of the DB, and the LAD-DB angle. SBO was defined as a persistant reduction in the TIMI flow to ≤1 by the end of the procedure. Results:The PA of the branch-side semicircle, the vessel diameter and the ostial lumen diameter of the DB all significantly affected the SBO. The total PA and the %AS of the LAD were not related to the SBO. Multivariate analysis identified that the PA of the branch-side semicircle was the only predictor of SBO (odds ratio 3.2, 95% confidence interval 1.3 to 8.6, p=0.015). Conclusion:It appears that the plaque distribution of LAD is a major determinant of SBO. These findings support the theory that the plaque shift (“snow plow effect”) may be the mechanism of the SBO following stenting. (Korean Circulation J 2002;32(8):655-665)

Incidence and angiographic predictors of side branch occlusion following high-pressure intracoronary stenting

We evaluated the incidence, angiographic predictors, and clinical outcome of side branch occlusion (SBO) following high-pressure intracoronary stenting in 175 patients. All stent implants during a 7-month period were reviewed for the incidence of major (>1 mm) SBO. Side branches were further characterized based on side branch and index lesion morphology. Clinical events (death, myocardial infarction, and target vessel revascularization rates) were determined at 9 months. A total of 175 patients (182 lesions) had 224 major side branches covered by intracoronary stents. Of these, 43 (19%) occluded. Most SBOs (29 of 43 [67%]) occurred after poststent dilation using high-pressure inflations (15.3 ± 3.3 atmospheres). No clinical characteristics correlated with SBO. By multivariate analysis, those side branches with >50% ostial narrowing that arose from within or just beyond the diseased portion of the parent vessel (threatened side branch morphologies) were a powerful angiographic predictor of SBO (odds ratio 40, 95% confidence interval, 14 to 130, p < 0.0001). At 9-month follow-up there was no difference in combined clinical events between those patients with and without SBO. These data demonstrate that side branches with ostial stenoses in continuity with diseased parent lesions were at risk of occlusion following stenting. SBO, however, was not associated with adverse clinical outcome. These findings lend support to plaque shift (“snow plow effect”) as the mechanism behind SBO following stent placement.