Impact of various intravascular ultrasound criteria for stent optimization on the six-month angiographic restenosis

Intravascular Ultrasound in Chronic Total Occlusion Percutaneous Coronary Intervention: Solving Ambiguity and Improving Durability

Chronic total occlusions remain among the most technically challenging lesions to treat percutaneously. Limitations of 2-dimensional angiography may further hinder successful treatment of these lesions. Intrasvascular ultrasound has a key role in percutaneous recanalization for a chronic total occlusion by providing key lesion characteristics, facilitating guidewire crossing, elucidating the intraplaque or extralaque path of the guidewire, optimizing lesion preparation, guiding stenting and identifying suboptimal results. Live visualization of the guidewire during crossing may reduce extraplaque wire tracking. This review describes the practical uses of intravascular imaging for commonly encountered scenarios when treating chronic total occlusions.

Optimisation of percutaneous coronary intervention: indispensables for bioresorbable scaffolds

INTRODUCTION

With new developments in percutaneous coronary intervention (PCI), such as the introduction of bioresorbable scaffolds (BRS), percutaneous treatment of coronary artery diseases has entered a new era. Without metallic remnants, BRSs appear able to overcome several limitations of the existing metallic stents and provide a physiologic treatment of coronary artery pathology.

AREAS COVERED

BRS have different mechanical properties compared to the traditional metallic stents that should be taken into account during their implantation. Lesion selection, device sizing and satisfied pre-dilatation should be implemented prudently. Although intravascular imaging is not mandatory for the implantation of BRSs it may have a value in optimizing device deployment assess final results and reduce the risk of device related adverse events such as re-stenosis, or scaffold thrombosis. This review aims to reveal the crucial points about the methods of optimization in each steps of BRS implantation. Expert commentary: The target lesions for BRS should be selected meticulously. Pre-dilatation, post-dilatation and intra-vascular imaging techniques should be implemented appropriately to avoid undesirable events after scaffold implantation.

Optimization of stent deployment by intravascular ultrasound

Intravascular ultrasound (IVUS) is a useful diagnostic method that provides valuable information in addition to angiography regarding the coronary vessel lumen, dimensions, plaque burden, and characteristics. The major use of IVUS in coronary intervention is to guide interventional strategies and assess optimal stent deployment. Since the introduction of the drug-eluting stent (DES), concerns about restenosis have decreased. However, high-risk lesion subsets are being routinely treated with DESs, and the incidence of suboptimal results after stent deployment, such as stent underexpansion, incomplete stent apposition, edge dissection, geographic miss, and the risk of stent thrombosis, have correspondingly increased. Thus, optimization of stent deployment under IVUS guidance may be clinically important. In this review, we focus on the potential role of IVUS in stent optimization during percutaneous coronary intervention and its clinical benefits.

Assessment of coronary stent deployment using computer enhanced x-ray images-validation against intravascular ultrasound and best practice recommendations

OBJECTIVE

To investigate the accuracy of stent measurements using coronary x-ray angiograms with a computer based stent enhancement algorithm applied (StentBoost, SB). To derive recommendations for best practice when using such systems.

BACKGROUND

Computer enhancement algorithms allow better visualization of intracoronary stents to assist in ensuring adequate stent deployment. Factors that affect the accuracy of measurements taken on such systems are yet to be fully understood.

METHODS

We analysed stent deployment of 43 stents in 33 patients measuring minimum stent diameter and cross sectional area (CSA) using intravascular ultrasound (IVUS), SB enhanced x-ray images, and quantitative coronary angiography (QCA). We investigated if the use of two projections and method of calibration influenced correlation between IVUS and SB measurements.

RESULTS

Using two views and performing calibration via the guide catheter improved agreement between SB and IVUS measurements. For example, minimum stent diameter assessed with SB using one view and balloon markers for calibration produced a correlation coefficient, r, of 0.21, whereas using two views and the guide catheter for calibration increased agreement to r = 0.62. Relative measures of stent deployment, such as the ratio of minimum to maximum CSA, produced good correlation between IVUS and SB (r = 0.74).

CONCLUSIONS

When using the SB system, two projection angles should be used to image the stent. For absolute measurements, the guide catheter should be used for calibration purposes. Relative measures of stent size, which are probably sufficient for assessment of deployment, also give good agreement with similar measures on IVUS, and require no calibration.

Incidence of stent under-deployment as a cause of in-stent restenosis in long stents

Although stent under-deployment (SU) has been associated with increased risk of in-stent restenosis, little data have been reported on the incidence of SU in patients presenting with clinical in-stent restenosis. In 59 patients referred for vascular brachytherapy and showing angiographic in-stent restenosis, we sought (1) to determine the incidence of SU using standard intravascular ultrasound (IVUS) criteria (2) to evaluate the effects of repeat angioplasty on further stent expansion. Stented length was 32+/-17 mm and diameter stenosis was 75+/-14%. Before re-intervention, the incidence of reduced absolute values of minimal stent cross-sectional area (MSCSA) varied from 69% (< or =8 mm2) to 15% (< or =5 mm2). After re-intervention, the incidence decreased to 24% (< or =8 mm2) (p = 0.0001) and 0% (< or =5 mm2) (p = 0.005). Before re-intervention, SU as assessed by relative criteria varied from 21% (80% mean reference lumen area or 90% minimum distal reference lumen area) to 28% (100% minimum reference lumen area). After re-intervention, the incidence of SU varied from 7% (90% minimum distal reference lumen area) (p = 0.0001 vs. pre) to 24% (55% mean reference EEM area) (p = ns). No change in strut apposition (97% pre vs. 100% post) nor in symmetry index (100% pre vs. post) was noted. From all criteria, the 90 and 100% minimum reference lumen area criteria were the most altered by repeat balloon dilatation, 21% pre vs. 7% post and 28% pre vs. 11% post, respectively. In conclusion, among patients presenting with severe angiographic in-stent restenosis, a significant number showed signs of SU whose incidence varied according to applied criteria. Significant stent re-expansion can be obtained following IVUS-guided repeat angioplasty irrespective of initial SU criteria.

Randomized comparison of debulking followed by stenting versus stenting alone for ostial left anterior descending artery stenosis: intravascular ultrasound guidance

BACKGROUND

Although directional coronary atherectomy (DCA) before stenting has the advantage of combining substantial removal of atheromatous plaque and prevention of elastic recoil, there has been no randomized study to investigate its efficacy in ostial left anterior descending artery (LAD) lesions. This study was aimed to evaluate the effect of DCA followed by stenting on ostial LAD stenosis under the guidance of intravascular ultrasound (IVUS).

METHODS

Eighty-six patients with ostial LAD stenoses were randomly assigned to DCA followed by stenting (group I) or stenting alone (group II). Aggressive DCA or optimal stenting was performed in both groups under the guidance of IVUS. The primary end point was angiographic restenosis at 6 months.

RESULTS

Baseline clinical and angiographic characteristics were similar between the 2 groups. The postprocedural minimal lumen diameter was larger in group I than group II (4.0 +/- 0.4 mm vs. 3.5 +/- 0.5 mm, P <.001). However, the angiographic restenosis rates were not significantly different between the 2 groups (9/32 [28.1%] in group I vs. 11/30 [36.7%] in group II, P =.472). The postprocedural IVUS stent area was the only independent determinant of restenosis by multivariate analysis (odds ratio.61, 95% CI 0.41-0.92, P =.018).

CONCLUSIONS

DCA followed by stenting achieved greater lumen gain than stenting alone for ostial LAD stenosis. However, DCA did not improve angiographic restenosis.

Stenting after directional coronary atherectomy compared with directional coronary atherectomy alone and stenting alone: a serial intravascular ultrasound study

BACKGROUND

Directional coronary atherectomy prior to stent implantation (DCA-stent) is expected to be an effective approach to reduce restenosis. The purpose of this study was to determine whether DCA-stent has advantages over DCA alone or stenting alone using serial intravascular ultrasound (IVUS).

METHODS AND RESULTS

Serial (pre-, post- and follow-up) IVUS was performed in 187 native coronary lesions treated with each of the 3 strategies. External elastic membrane cross-sectional area (CSA), lumen CSA and plaque CSA were measured. Baseline characteristics were similar. Postprocedural lumen CSA was largest after DCA-stent (11.2+/-2.7 mm2) and DCA (10.8+/-2.5 mm2) than stenting alone (9.0+/-2.9 mm2) (p<0.0005). Follow-up lumen loss was similar. As a result, follow-up lumen CSA was largest after DCA-stent (DCA-stent: 9.1+/-3.4 mm2, DCA: 7.8+/-4.2 mm2, stent: 6.3+/-2.6 mm2, p<0.0005). There was a trend toward a lower rate of restenosis with DCA-stent (DCA-stent, 12.5%; DCA, 18.3%; stent, 18.8%; p=0.57).

CONCLUSIONS

DCA-stent is superior to both DCA alone and stent alone in terms of the ability to gain a larger lumen as assessed by IVUS.