In-stent Lumen Research Articles

Improvement of in-stent lumen measurement accuracy with new High-Definition CT in a phantom model: comparison with conventional 64-detector row CT

The purpose of this study was to evaluate improvement of measurement accuracy of in-stent lumen using coronary stent phantoms on new high-definition CT (HDCT) compared with conventional 64 detector-row CT (MDCT). To estimate the spatial resolution, a high-resolution insert of CATPHAN (The Phantom Laboratory, NY, USA) was scanned by both HDCT (Discovery CT750 HD) and MDCT (LightSpeed VCT). Also, we developed six types of stent phantom, which have 2.5- and 3.0-mm-diameter with three different types of stents (Velocity: Johnson & Johnson, Driver: Medtronic, Multilink-Rx: Guidant). A 50% stenotic segment made of acrylic resin was built at the center inside the stent. Those coronary vessel phantoms were made of acrylic resin and filled with diluted Iodine (350 HU in 120 kVp), and each stent was fixed inside of those vessels. Those phantoms in water-filled tank were scanned on both HDCT and MDCT. The luminal diameter obtained using digital calipers at five different points and the mean luminal diameter (MLD) were calculated. The underestimate ratio (UR) and △UR was defined as follows: UR = [True diameter of stent-MLD]/True diameter of stent; △UR = [MLD at HDCT-MLD at MDCT]/True diameter of stent. The spatial resolution was estimated to be 0.71 mm on MDCT and 0.50 mm on HDCT. At the non-stenotic segments, the △URs were 11.6% (Velocity), 16.4% (Driver) and 7.2% (Multilink) for the 2.5-mm stents, and 14.0% (Velocity), 16.3% (Driver) and 13.3% (Multilink) for the 3.0-mm stents. At the stenotic segment, the △URs were 23.2% (Velocity), 8.0% (Driver) and 13.6% (Multilink) for the 2.5-mm stents, and 20.0% (Velocity), 14.7% (Driver) and 15.3% (Multilink) for the 3.0-mm stents. Superior spatial resolution of HDCT could be promising for more accurate measurement of in-stent diameter.

Assessment of coronary stent lumen visibility and patency by dual-source computed tomographic angiography

To assess the in-stent lumen visibility and image quality of coronary stents by dual-source computed tomography (DSCT) coronary angiography, and the diagnostic accuracy of DSCT in the detection of coronary in-stent restenosis. DSCT was performed at 147 stents in 78 patients at an interval of (21.8?22.2) months after coronary stent implantation. Axial multi-planar reconstruction of the stents and curved-planar reconstruction through the median of the stents were evaluated for stent image quality on a 5-point scale, and the stent lumen diameters were detected. Thirty out of these 78 patients underwent conventional coronary angiography within one month after CT angiography. The patency of 60 stents were independently evaluated by two blinded readers. Image quality was good to excellent on average score (1.6?0.6) . Stent image quality score was correlated with stent diameter, stent location, and heart rate. All stents were assessable in lumen visibility with an average visible lumen diameter percentage of (72.2?12.2) %. Visible lumen diameter percentage was correlated with stent diameter and stent location. For the stents with calcified plaques, the visible lumen diameter percentage at the calcified site was significantly lower than that at the non-calcified site (P<0.001) . Compared with the conventional coronary angiography, 12 out of 14 in-stent stenoses were correctly detected. The sensitivity, specificity, positive predictive value, and negative predictive value for the detection of in-stent stenosis was 85.7%, 95.7%, 85.7%, and 95.7%, respectively. For stents whose diameter >0.275cm, the sensitivity, specificity, positive predictive value, and negative predictive value were all 100%. The agreement between CT findings and coronary angiography results was 93.3%, and it was correlated with stent diameter and heart rate. Using a DSCT, coronary stent lumen is partially visible and the image quality is high. Stent diameter and location can influence the stent lumen visibility and image quality. DSCT has a high diagnostic accuracy for the detection of in-stent restenosis and may be a valuable modality for the follow-up of coronary artery stent patency."

Evaluation of coronary artery in-stent restenosis with prospectively ECG-triggered axial CT angiography versus retrospective technique: a phantom study

This study compared the performance of prospectively electrocardiographically (ECG)-triggered axial computed tomography (CT) angiography with retrospective technique in evaluating coronary artery stent restenosis by 64-slice CT. A pulsing cardiac phantom with artificial coronary artery in-stent restenosis was examined by CT angiography with different types of scan modes. The visibility of in-stent restenosis was evaluated with a three-point score. Artificial lumen narrowing [(inner stent diameter-measured lumen diameter)/inner stent diameter], lumen attenuation increase ratio [(in-stent attenuation-coronary artery lumen attenuation)/coronary artery lumen attenuation], measurement error of restenosis percent [(known restenosis percent-measured restenosis percent)/known restenosis percent] and imaging noise were analysed. Prospective acquisition showed better visibility than retrospective acquisition (p<0.05): 61% of in-stent restenoses had good visibility on the prospective acquisition compared with 17% on the retrospective acquisition. Furthermore, the effective dose was 6.2 ± 0.3 mSv for the prospective technique compared with 18.8 ± 1.1 mSv for the retrospective technique. Artificial lumen narrowing (mean 40%), lumen attenuation increase ratio (mean 33%) and measurement error of restenosis percent were not different between types of CT acquisitions. Compared with the traditional retrospective technique, prospective coronary CT angiography offers improved image quality and reduces effective radiation dose in evaluating in-stent restenosis.

E0533 The effect of QCA in left main lesion

ObjectiveUsing Intravascular ultrasound (IVUS) as a standard to evaluate the ability of Quantitative Coronary Angiography (QCA) in judging the lumen diameter before and after percutaneous coronary intervention (PCI) in left...

In vitro evaluation of 56 coronary artery stents by 256-slice multi-detector coronary CT

Objective We sought to investigate stent lumen visibility of 56 coronary stents with the newest 256-multi-slice-CT (256-MDCT) technology for different reconstruction algorithms in an in vitro model. Background Early identification of in-stent restenosis (ISR) is important to avoid recurrent ischemia and prevent acute myocardial infarction (AMI). Since angiography has the disadvantage of high costs and its invasiveness, MDCT could be a convenient and safe non-invasive alternative for detection of ISR. Material and methods Percentages of in-stent lumen diameter and in-stent signal attenuation (measured as contrast-to-noise ratio (CNR)) of 56 coronary stents (group A ≤2.5 mm; group B = 2.75–3.0 mm; group C = 3.5–4.0 mm) were evaluated in a coronary vessel in vitro phantom (iodine-filled plastic tubes) employing four different reconstruction algorithms (XCD, CC, CD, XCB) on a novel 256-MDCT (Philips-iCT, collimation = 128 mm × 0.625 mm; rotation time = 270 ms; tube current = 800 mA s with 120 kV). Analysis was conducted with the semi-automatical full-width-at-half-maximum (FWHM) method. P-values <0.05 were regarded statistically significant. Results In-stent lumen diameter >60% for group C stents was significantly larger and CNR was significantly lower (both p < 0.05) for sharp kernels (CD; XCD) when compared to groups A/B. The FWHM-method showed significantly smaller in-stent lumen diameter ( p < 0.05) when compared to the manual method. Conclusion 256-MDCT could potentially be employed for clinical assessment of stent patency in stents >3.0 mm when analysed with cardio-dedicated sharp kernels, although clinical studies corroborating this claim should be performed. However, stents ≤3.0 mm reconstructed by soft kernels revealed insufficient in-stent lumen visualisation and should not be used in clinical practice. Further improvements in spatial and temporal image resolution as well as reductions of radiation exposure and image noise have to be accomplished for the ambitious goal of characterising both CT coronary artery anatomy and in-stent lumen.

High-Pitch 128-Slice Dual-Source CT for the Assessment of Coronary Stents in a Phantom Model

To evaluate the quality of stent lumen delineation using dual-source computed tomography (DSCT) in the standard-pitch mode (SP) as compared to the high-pitch mode (HP) in a phantom study. Forty different coronary stents placed in plastic tubes filled with contrast agent were imaged with a second generation DSCT system in a SP (pitch 0.23) and HP (pitch 3.4) mode in orientations of 0°, 45°, and 90° relative to the z-axis. Two observers independently measured the in-stent lumen and the attenuation values in the center of the stents. The artificial lumen narrowing (ALN) was calculated using the measured in-stent lumen and the nominal diameter of the plastic tube. Interobserver correlation was excellent for in-stent lumen (0.86) and attenuation measurements (0.91). There was no significant difference neither for ALN (SP: 54.7-62.8%; HP: 55.8-64.0%) nor attenuation (SP: 356-395 Hounsfield units [HU]; HP: 352-384 HU) between SP and HP mode. For both modes, the orientation of the stent relative to the z-axis significantly affected ALN and attenuation (each P < .001). CT volume dose index was significantly lower using HP mode as compared to SP mode (P < .001). The HP mode in DSCT provides visualization of the coronary in-stent lumen comparable to that measured in SP mode while reducing applied radiation dose in a stationary phantom model.

Comparing different MR angiography strategies of carotid stents in a vascular flow model: toward stent-specific recommendations in MR follow-up

IntroductionCarotid artery stenting (CAS) requires adequate follow-up imaging to assess complications such as in-stent stenosis or occlusion. Options include digital subtraction angiography, CT angiography, ultrasound, and MR angiography (MRA), which may offer a non-invasive option for CAS follow-up imaging. The aim of this study was to assess contrast-enhanced MRA (CE-MRA) and three-dimensional time-of-flight MRA (3D-TOF) for visualization of the in-stent lumen in different carotid stents.MethodsIn this study, we compared CE-MRA and 3D-TOF of five different carotid stents (Guidant Acculink®, Cordis Precise®, Boston Wallstent®, Abbot Vascular Xact®, Cook Zilver®) in three diameters (4, 6, and 8 mm) using a vascular flow model at 3.0 T with the help of a recently developed carotid surface coil. Stent-related artifacts were objectively assessed by calculating artificial lumen narrowing (ALN) and relative in-stent signal (RIS).ResultsRIS and ALN depended heavily on stent type, stent diameter, and the employed MR sequence. ALN and RIS were relatively favorable for Acculink®, Precise®, and Zilver® stents with both CE-MRA and 3D-TOF. CE-MRA provided better results for the Wallstent, while the Xact stent was difficult to visualize with both MRA protocols.ConclusionBoth CE-MRA and 3D-TOF are viable options for depicting the in-stent lumen in carotid stents. For specific stents, 3D-TOF provided image quality comparable to CE-MRA and may thus be suitable for in vivo assessment. Development of stent-specific pathways for follow-up imaging seems advisable to address stent-related differences in image quality.

Coronary artery stent imaging with 128-slice dual-source CT using high-pitch spiral acquisition in a cardiac phantom: comparison with the sequential and low-pitch spiral mode

To evaluate coronary stents in vitro using 128-slice-dual-source computed tomography (CT). Twelve different coronary stents placed in a non-moving cardiac/chest phantom were examined by 128-slice dual-source CT using three CT protocols [high-pitch spiral (HPS), sequential (SEQ) and conventional spiral (SPIR)]. Artificial in-stent lumen narrowing (ALN), visible inner stent area (VIA), artificial in-stent lumen attenuation (ALA) in percent, image noise inside/outside the stent and CTDIvol were measured. Mean ALN was 46% for HPS, 44% for SEQ and 47% for SPIR without significant difference. Mean VIA was similar with 31% for HPS, 30% for SEQ and 33% for SPIR. Mean ALA was, at 5% for HPS, significantly lower compared with -11% for SPIR (p = 0.024), but not different from SEQ with -1%. Mean image noise was significantly higher for HPS compared with SEQ and SPIR inside and outside the stent (p < 0.001). CTDIvol was lower for HPS (5.17 mGy), compared with SEQ (9.02 mGy) and SPIR (55.97 mGy), respectively. The HPS mode of 128-slice dual-source CT yields fewer artefacts inside the stent lumen compared with SPIR and SEQ, but image noise is higher. ALN is still too high for routine stent evaluation in clinical practice. Radiation dose of the HPS mode is markedly (less than about tenfold) reduced.

Evaluation of Coronary Artery In-stent Restenosis by 64-Section Computed Tomography

To determine factors affecting the ability of 64-multislice computed tomography (MSCT) to detect, assess, and accurately diagnose significant coronary arterial in-stent restenosis (ISR). The institutional review board approved this study and waived informed consent. Sixty patients underwent CT coronary angiography using 64-MSCT, after implantation of coronary artery stents (n=91). We assessed diagnostic accuracy for ISR with CT in comparison with conventional coronary angiography as the gold standard, visually and with measurement of in-stent coronary lumen density. Possible factors that influenced the diagnostic performance of CT were evaluated, which included image quality (IQ), stent characteristics, and location. Sixty-nine stents (75.8%) were assessable. Low IQ, location in the left circumflex coronary artery, and narrow stent diameter were associated with poor assessment (P<0.05). In stents that could be assessed, sensitivity, specificity, positive predictive value, and negative predictive value of 64-MSCT were 90.0%, 73.5%, 58.1%, and 94.7%, respectively, for significant ISR. The diagnostic accuracy in assessable stents showed a significant increase with better IQ, thinner strut thickness, and nondrug eluting stent. False-positive diagnoses of ISR by CT were explained by coronary lumen density measurements. Evaluation of stents by 64-MSCT is not recommended in stents with diameters of < or = 2.75 mm or stents located at the left circumflex coronary artery. The diagnostic accuracy of 64-MSCT is affected by IQ and strut thickness in assessable stents. Significant ISR can be excluded with high reliability in selected patients.

Effect of Statin on the Reference Segments after Bare-Metal Stent Implantation

Effect of Statin on the Reference Segments after Bare-Metal Stent Implantation

The challenge of coronary stent imaging

Although cardiac computed tomography (CT) has become an accepted diagnostic option for the management of patients with suspected coronary artery disease (CAD), its utility is less evident in patients with established CAD, for instance after percutaneous coronary intervention (PCI). Most of the currently available stent devices are made of metal for radial strength after expansion combined with longitudinal flexibility. Despite these mechanical advantages, the metal is also responsible for strong roentgen attenuation, which complicates noninvasive angiographic assessment by cardiac CT. Disproportional attenuation of low-energy photons by the stent shifts the roentgen spectrum of the remaining x-ray toward higher energy levels (beam hardening), which decreases roentgen attenuation and causes shadowing behind high-density material on CT images. In addition, the relatively limited spatial resolution of cardiac CT combined with convolution filters and residual coronary motion increases the apparent size of stent struts on CT (blooming artifacts). Although the extent of interference highly varies between different stent types (in terms of the type of metal and stent design), in vitro studies of stationary stents showed that on average nearly one-half of the in-stent lumen is affected by these blooming artifacts. 1 Nieman K. Cademartiri F. Raaijmakers R. Pattynama P. de Feyter P. Noninvasive angiographic evaluation of coronary stents with multi-slice spiral computed tomography. Herz. 2003; 28: 136-142 Crossref PubMed Scopus (73) Google Scholar , 2 Maintz D. Seifarth H. Raupach R. Florh T. Rink M. Sommer T. Ozgun M. Heindel W. Fischbach R. 64-slice multidetector coronary CT angiography: in vitro evaluation of 68 different stents. Eur Radiol. 2006; 16: 818-826 Crossref PubMed Scopus (190) Google Scholar

Abstract 5767: Viral Anti-inflammatory Treatment of Unstable Coronary Syndromes: The VT-111 Acute Coronary Syndrome Trial

Background: Up-regulation of inflammatory responses contributes to coronary plaque rupture, thrombosis, and vascular occlusion leading to myocardial and cerebral infarction. Some viruses have developed potent proteins that block key steps in both the innate and adaptive immune responses. VT-111 is a viral serine proteinase inhibitor that demonstrates reductions in monocyte migration to sites of vascular damage in a wide range of animal models. Methods: In a double-blind, placebo-controlled trial, the safety of VT-111 plus standard of care was evaluated in patients with acute coronary syndromes treated with stents. Patients received IV VT-111 or placebo once daily for 3 days, starting immediately before intervention. Patients were followed for 3 days in hospital, and at 14, 28 days and 3 and 6 months for safety/efficacy endpoints, including biomarker analysis and MACE (death, MI or revascularization). At 6 months, restenosis was evaluated by intravascular ultrasound. Results: Forty-eight patients were enrolled at 7 sites; 19 patients received 5 μ g/kg VT-111, 17 patients received 15 μ g/kg and 12 patients received placebo. There were no differences between the treated and control groups on key safety endpoints, including coagulation parameters and adverse events. A trend towards a decrease in MACE was observed, with a reduction to 0% in the 15 μ g/kg group from 18% in controls. A significant, dose-dependent reduction in Troponin I levels was observed with VT-111 at 8, 16, 24 and 54 hours post-dose (p&lt;0.05). Similar reductions were observed in CK-MB levels at 8, 16 and 24 hours post-dose (p&lt;0.05). Trends towards a reduction in MCP-1 were also observed. Further analysis suggests that VT-111 may also have early effects on markers such as EN-RAGE (S100A12), IL-6 and CD40L. There were no differences in in-stent plaque area or lumen area between control and treated groups, as assessed by IVUS. Conclusion: This randomized, placebo-controlled trial supports the safety of 3 daily IV injections of VT-111, a first in class viral-derived anti-inflammatory therapeutic agent. A significant reduction in biomarkers of cardiac damage demonstrates the potential of this novel class of protein therapeutics.

Improved In-Stent Lumen Visualization using Intravascular MRI and a Balanced Steady-State Free-Precession Sequence

To investigate the ability of an intravascular magnetic resonance (MR) loopless antenna to reduce the radiofrequency shielding of a vascular stent during signal reception as a way to improve the visualization of the in-stent lumen. Using a balanced steady-state free-precession (bSSFP) sequence and a dedicated vascular phantom, the signal-to-noise ratio (SNR) inside the lumen of a stent is evaluated as a function of the nominal flip angle and compared with the results obtained for a reference vessel without a stent. All experiments are performed using successively an intravascular loopless antenna and surface arrays coils. Using an optimized protocol, in vitro in-stent restenosis visualization and quantification experiments are performed to evaluate the validity of an approach using an intravascular antenna and cross-sectional images to depict a vascular lesion inside a stent. The use of a loopless antenna effectively eliminates the radiofrequency shielding effect of the stent during signal reception. Furthermore, using a bSSFP sequence with a carefully chosen nominal flip angle, an equally good blood SNR can be obtained inside and outside the stent. Results of in vitro in-stent restenosis quantification measurements using the proposed method illustrate the benefits arising from the use of the intravascular antenna. In the perspective of MR-guided vascular interventions, the presented results illustrate that the use of an intravascular antenna can significantly facilitate imaging inside a vascular stent. Potential applications include the monitoring of stent deployment as well as visualization and quantification of in-stent restenosis during an intervention.

Assessment of Coronary Stents by 64-slice Computed Tomography: In-stent Lumen Visibility and Patency

To assess lumen visibility of coronary stents by 64-slice computed tomography (CT) coronary angiography, and determine the value of 64-slice CT in non-invasive detecting of in-stent restenosis after coronary artery stent implantation. Totally, 60 patients (54 males, aged 57.0+/-12.7 years) and 105 stents were investigated by 64-slice CT at a mean interval of 20.0+/-16.6 months after coronary stents implantation. Axial multi-planar reconstruction images of the stents and curved-planar reconstruction images through the median of the stents were reconstructed for evaluating stent image quality on a 5-point scale (1=excellent, 5=non-assessable), and stent lumen diameter was detected. Conventional coronary angiography was performed in 18 patients, and 32 stents were evaluated. Image quality was good to excellent on average (score 1.71+/-0.76). Stent image quality score was correlated to heart rate (r=0.281, P<0.01) and stent diameter (r=-0.480, P<0.001). All the stents were assessable in lumen visibility with an average visible lumen diameter percentage of 60.7%+/-13.6%. Visible lumen diameter percentage was correlated to heart rate (r=-0.193, P<0.05), stent diameter (r=0.403, P<0.001), and stent image quality score (r=-0.500, P<0.001). Visible lumen diameter percentage also varied depending on the stent type. In comparison with the conventional coronary angiography, 4 of 6 in-stent stenoses were correctly detected. The sensitivity and specificity for the detection of in-stent stenosis were 66.7% and 84.6%, respectively. Using a 64-slice CT, the stent lumen is partly visible in most of the stents. And 64-slice CT may be useful in the assessment of stent patency.

Evaluation of Coronary Stents With 64-MDCT: In Vitro Comparison of Scanners From Four Vendors

The purpose of this study was to compare 64-MDCT scanners from four vendors in the in vitro evaluation of coronary artery stents. Twelve coronary artery stents (nominal outer diameter, 2.5-5.0 mm) oriented in the z-axis were placed in a combined cardiac-chest phantom and imaged with 64-MDCT scanners from four vendors. Quantitative image quality parameters, including artificial in-stent luminal narrowing, image noise, and artificial in-stent luminal attenuation were measured on longitudinal and axial reformations. Imaging of stents with a luminal diameter of 3 mm or less and that of stents with a diameter greater than 3 mm also were compared. Artificial in-stent luminal narrowing was not different among the four vendors (range, 37-42%) on longitudinal reformations. Image noise inside the stent was significantly greater for one vendor (Siemens Healthcare; SD, 48 HU) than for the others (SD range, 21-26 HU) on longitudinal but not on axial images. For the same vendor, artificial in-stent luminal attenuation was significantly lower than for the other vendors. For all vendors, image noise inside the stent was significantly greater on axial than on longitudinal reformations (p < 0.001), and artificial luminal attenuation was significantly greater for all but one vendor (GE Healthcare). Stents 3 mm and narrower had significantly greater artificial luminal narrowing and artificial luminal attenuation (p < 0.05) than those with a diameter greater than 3 mm. For longitudinal reformations, scanners from the four leading vendors do not differ in artificial luminal narrowing, but there are differences in artificial luminal attenuation and image noise. The quality of images of the in-stent lumen is better on longitudinal reformations and for stents with a diameter greater than 3 mm. Except for image noise, differences between axial and longitudinal reformations are vendor specific.

“Intracoronary Whirling Current Phenomenon” and Thrombus Formation After Sirolimus-Eluting Stent Implantation Visualized by Optical Coherence Tomography

We present a case of imaged “intracoronary whirling current phenomenon.” A 60-year-old Japanese man was treated with 2 sirolimus-eluting stents (SES; 3.0×18 and 3.5×33 mm) in the right coronary artery (RCA) for chronic total occlusion in October 2007. After percutaneous coronary intervention, he was taking 200 mg of aspirin and 200 mg of ticlopidine. However, he had recurrent transient ischemic chest pain beginning at 7 months. A second coronary angiography at 8 months after SES implantation showed reocclusion at a site just proximal to the SES. A repeat percutaneous coronary intervention was performed for RCA chronic total occlusion (Figure 1). After crossing the guide wire to the distal portion of the RCA, the target lesion was dilated using a 1.25×10 mm balloon catheter. After minimum balloon dilatation, optical coherence tomography (OCT) was performed to evaluate in-stent reocclusion from the distal portion to the proximal portion (Figure 2). Two different types of tissue coverage (may be consistent with thrombus formations of different ages) were observed in the stent reocclusion.1 Moreover, in the patent distal portion of the RCA, an intracoronary whirling current …

Prospective ECG-triggered axial CT at 140-kV tube voltage improves coronary in-stent restenosis visibility at a lower radiation dose compared with conventional retrospective ECG-gated helical CT

The purpose of this study was to compare coronary 64-slice CT angiography (CTA) protocols, specifically prospective electrocardiograph (ECG)-triggered and retrospective ECG-gated CT acquisition performed using a tube voltage of 140 kV and 120 kV, regarding intracoronary stent imaging. Coronary artery stents (n = 12) with artificial in-stent restenosis (50% luminal reduction, 40 HU) on a cardiac phantom were examined by CT at heart rates of 50-75 beats per minute (bpm). The subjective visibility of in-stent restenosis was evaluated with a three-point scale (1 clearly visible, 2 visible, and 3 not visible), and artificial lumen narrowing [(inner stent diameter - measured lumen diameter)/inner stent diameter], lumen attenuation increase ratio [(in-stent attenuation - coronary lumen attenuation)/coronary lumen attenuation], and signal-to-noise ratio of in-stent lumen were determined. The effective dose was estimated. The artificial lumen narrowing (mean 43%), the increase of lumen attenuation (mean 46%), and signal-to-noise ratio (mean 7.8) were not different between CT acquisitions (p = 0.12-0.91). However, the visibility scores of in-stent restenosis were different (p < 0.05) between ECG-gated CTA techniques: (a) 140-kV prospective (effective dose 4.6 mSv), 1.6; (b) 120-kV prospective (3.3 mSv), 1.8; (c) 140-kV retrospective (16.4-18.8 mSv), 1.9; and (d) 120-kV retrospective (11.0-13.4 mSv), 1.9. Thus, 140-kV prospective ECG-triggered CTA improves coronary in-stent restenosis visibility at a lower radiation dose compared with retrospective ECG-gated CTA.

Early- and Long-Term Intravascular Ultrasound and Angiographic Findings After Bioabsorbable Magnesium Stent Implantation in Human Coronary Arteries

This study aimed to evaluate the degradation rate and long-term vascular responses to the absorbable metal stent (AMS). The AMS demonstrated feasibility and safety at 4 months in human coronary arteries. The PROGRESS-AMS (Clinical Performance and Angiographic Results of Coronary Stenting) was a prospective, multicenter clinical trial of 63 patients with coronary artery disease who underwent AMS implantation. Angiography and intravascular ultrasound (IVUS) were conducted immediately after AMS deployment and at 4 months. Eight patients who did not require repeat revascularization at 4 months underwent late angiographic and IVUS follow-up from 12 to 28 months. The AMS was well-expanded upon deployment without immediate recoil. The major contributors for restenosis as detected by IVUS at 4 months were: decrease of external elastic membrane volume (42%), extra-stent neointima (13%), and intra-stent neointima (45%). From 4 months to late follow-up, paired IVUS analysis demonstrated complete stent degradation with durability of the 4-month IVUS indexes. The neointima was reduced by 3.6 +/- 5.2 mm(3), with an increase in the stent cross sectional area of 0.5 +/- 1.0 mm(2) (p = NS). The median in-stent minimal lumen diameter was increased from 1.87 to 2.17 mm at long-term follow-up. The median angiographic late loss was reduced from 0.62 to 0.40 mm by quantitative coronary angiography from 4 months to late follow-up. Intravascular ultrasound imaging supports the safety profile of AMS with degradation at 4 months and maintains durability of the results without any early or late adverse findings. Slower degradation is warranted to provide sufficient radial force to improve long-term patency rates of the AMS.

Restenosis in coronary bare metal stents. Importance of time to follow-up: A comparison of coronary angiograms 6 months and 4 years after implantation

Objectives. Angiographic late lumen loss measured 6 to 9 month after bare metal stent implantation in the coronary arteries is a validated restenosis parameter. Design. We performed a second angiographic follow-up after 4 years in event free survivors from the DANSTENT trial cohort. Results. Quantitative comparison of paired coronary angiograms at 6 months and 4 years showed a reduction of late loss from 0.68±0.52mm to 0.42 (±0.52) (mean difference 0.26 (0.17 to 0.36), p<0.0001). Minimal instent lumen diameter had increased from 2.39±0.62mm to 2.64±0.56mm (mean difference: −0.24mm, 95% confidence interval: −0.34mm to −0.14mm, p<0.0001). Instent diameter stenosis decreased from 24.8±14.2% to 18.6±9.3% (mean difference 6.16%, 95% confidence interval: 2.82 to 9.48%, p=0.0006). This observed spontaneous decrease of instent restenosis corresponds to a 19% increase of minimal cross-sectional vessel area and a 39% reduction of the binary restenosis rate over time. Conclusions. Instent late lumen loss in bare metal stents decreases spontaneously over time. Maturation of early hyperplastic tissue reaction after stent implantation with subsequent thinning of fibrotic tissue might explain this phenomenon.

Atherosclerotic Peripheral Vascular Disease Symposium II

Percutaneous intervention for peripheral artery disease has evolved from balloon angioplasty for simple focal lesions to multimodality techniques that enable treatment of severe arterial insufficiency. This technological expansion comes without a standard approach or algorithm, which makes the decision-making process more subjective than objective. Nevertheless, clinical tools are available that can have a favorable effect on patient care, and these promote usage. So, when are standard endovascular techniques (such as balloon and stents) good enough, and when are the latest advances (eg, atherectomy, drug-eluting stents) more appropriate? This section will address these questions for acute limb ischemia (ALI) and chronic critical limb ischemia (CLI). It will also delineate the problem of restenosis, particularly of the superficial femoral artery (SFA), and describe treatment alternatives. The discussion will review the role of drug-eluting stents, atherectomy devices, reentry catheters, and brachytherapy, as well as their potential complications and appropriate remedies. Treatment algorithms for aortoiliac and infrainguinal disease are provided in Figures 1 through 3⇓⇓. Figure 1. Treatment algorithm for acute lower-limb ischemia. *Short infusion of thrombolytic therapy proximal to occlusion can be used to facilitate wire traversal. Figure 2. Simplified treatment algorithm for symptomatic aortoiliac disease in patients deemed candidates for revascularization. In patients with multilevel disease, the aortoiliac segment should be addressed first. TASC indicates TransAtlantic Inter-Society Consensus; AI, aortoiliac; PTA, percutaneous transluminal angioplasty; PE, physical examination; ABI, ankle-brachial index; and U/S, ultrasound. Figure 3. Simplified treatment algorithm for symptomatic infrainguinal peripheral arterial disease, assuming concomitant aortoiliac disease has been treated and the patient is an acceptable candidate for revascularization. *Alternative therapies to PTA include cryotherapy, atherectomy (directional, rotational, ablative), and cutting balloon. †Alternative stent options include stent (graft, balloon expanding, and self expanding) and drug-eluting stent. PTA indicates percutaneous transluminal angioplasty; TASC, TransAtlantic Inter-Society Consensus; PE, physical examination; …