Does the specific intravascular ultrasound criterion used to optimize stent expansion have an impact on the probability of stent restenosis?

Outcomes With Intravascular Ultrasound and Optical Coherence Tomography Guidance in Percutaneous Coronary Intervention

Intracoronary imaging has become an important tool in the treatment of complex lesions with percutaneous coronary intervention (PCI). This retrospective cohort study identified 1,118,475 patients with PCI from the Nationwide Readmissions Database from 2017 to 2019. Intravascular ultrasound (IVUS) and optical coherence tomography (OCT) were identified with appropriate International Classification of Diseases, Tenth Revision codes. The primary outcome was major adverse cardiac events. The secondary outcomes include net adverse clinical events (NACEs), all-cause mortality, myocardial infarction (MI) readmission, admission for stroke, and emergency revascularization. The multivariate Cox proportional hazard regression was used to adjust for demographic and co-morbid confounders. Of 1,118,475 PCIs, 86,140 (7.7%) used IVUS guidance and 5,617 (0.5%) used OCT guidance. The median follow-up time was 184 days. The primary outcome of major adverse cardiac events was significantly lower for the IVUS (6.5% vs 7.6%; hazard ratio [HR] 0.89, 95% confidence interval [CI] 0.86 to 0.91, p <0.001) and OCT (4.4% vs 7.6%; HR 0.69, 95% CI 0.61 to 0.79, p <0.001) groups. IVUS was associated with significantly lower rates of NACEs (8.4% vs 9.4%; HR 0.92, 95% CI 0.89 to 0.94, p <0.001), all-cause mortality (3.5% vs 4.3%; HR 0.85, 95% CI 0.82 to 0.88, p <0.001), readmission for MI (2.7% vs 3.0%; HR 0.95, 95% CI 0.91 to 0.99, p = 0.012), and admission for stroke (0.5% vs 0.6%; HR 0.86, 95% CI 0.78 to 0.95, p = 0.002). OCT was associated with significantly lower rates of NACEs (6.6% vs 9.4%; HR 0.81, 95% CI 0.73 to 0.89, p <0.001) and all-cause mortality (1.8% vs 4.3%; HR 0.51, 95% CI 0.42 to 0.63, p <0.001). Emergency revascularization was not significantly different with IVUS guidance. Readmission for MI, stroke, and emergency revascularization were not significantly different with OCT guidance. A subgroup analysis of patients with ST-elevation MI and non-ST-elevation MI showed similar results. In conclusion, the use of IVUS and OCT guidance with PCI were associated with significantly lower rates of morbidity and mortality in real-world practice.

Definition of Optimal Optical Coherence Tomography-Based Stent Expansion Criteria: In-Stent Minimum Lumen Area Versus Residual Stent Underexpansion

BACKGROUND

The mismatch between in-stent minimum lumen area (sMLA) and reference vessel lumen area, defined as stent underexpansion (SU), could be an important determinant of stent failure. We tested the clinical predictive value of absolute sMLA in comparison to relative SU in the context of the CLI-OPCI (Centro Per La Lotta Contro L'Infarto-Optimisation of Percutaneous Coronary Intervention) project registry.

METHODS

We retrospectively analyzed end procedural optical coherence tomography findings in 1211 patients (1422 lesions) undergoing percutaneous coronary intervention, assessing the prevalence and magnitude of residual SU and exploring correlation with outcome in comparison with sMLA.

RESULTS

In our series, both sMLA and SU were related to vessel size and anatomic lesion complexity. When compared with patients without adverse event at follow-up, those experiencing device-oriented cardiovascular events (composite of cardiac death, target vessel myocardial infarction, target lesion revascularization, and stent thrombosis) showed a lower sMLA (5.6±2.1 versus 6.1±2.1 mm²; P=0.011) but a comparable degree of SU (11.6±14.1% versus 11.2±13.3%; P=0.734). The prespecified cutoff value of sMLA <4.5 mm², documented in 23.8% of cases, was confirmed as independent outcome predictor for device-oriented cardiovascular events (hazard ratio [HR], 2.05 [95% CI, 1.5-2.9]) including target lesion revascularization (HR, 2.43 [95% CI, 1.7-3.5]) and stent thrombosis (HR, 3.23 [95% CI, 1.7-6.3]). A residual SU of 10%, 20%, and 30% was observed in 38.0%, 18.2%, and 7.6% of cases, respectively. No grade of residual SU significantly increased the risk of stent failure, unless if an SU >20% was associated with an sMLA <4.5 mm² (HR, 3.11 [95% CI, 1.7-5.6]). Finally, an association between stent overexpansion (ie, >110%) and device-oriented cardiovascular events was also observed (HR, 1.60 [95% CI, 1.1-2.3]).

CONCLUSIONS

Final absolute sMLA and not relative SU was associated with an increased risk of stent failure. A variable grade of SU was common, but it resulted in being clinically relevant only when associated with an sMLA <4.5 mm².

Clinical Outcomes and Unique Restenosis of Calcified Nodule in Heavily Calcified Coronary Artery

AIMS

Calcified nodule (CN) has been known as the advanced stage of coronary calcification. However, clinical outcomes following percutaneous coronary intervention (PCI) to CN remain unknown. This study aimed to compare clinical outcomes, including target lesion revascularization (TLR), between calcified coronary lesions with and without CN.

METHODS

Two hundred forty-nine lesions undergoing intravascular ultrasound-guided PCI with rotational atherectomy (RA) were enrolled and divided into the CN group (n=100) and the non-CN group (n=149) according to the presence of CN. The cumulative incidence of clinically driven TLR (CD-TLR) and the reasons for CD-TLR were compared between the CN and non-CN groups.

RESULTS

The incidence of CD-TLR was significantly higher in the CN group than in the non-CN group. In the landmark analysis at 1 year, the CN group showed a significantly higher incidence of CD-TLR within 1 year. However, the incidence of CD-TLR beyond 1 year was numerically lower in the CN group than in the non-CN group. In the multivariate Cox hazard model, CN was significantly associated with CD-TLR. In the CN group, in-stent CN was the major reason for CD-TLR (52%) and was observed mainly within 1 year (90%).

CONCLUSIONS

In the heavily calcified lesions requiring RA, CN was the factor associated with the higher rate of CD-TLR especially within 1 year. The timing of CD-TLR in lesions with CN may indicate that the process of CN protruding through the struts was progressed monthly.

Intravascular imaging in coronary stent restenosis: Prevention, characterization, and management

Despite the introduction of drug-eluting stents to combat the neointimal hyperplasia that occurred after BMS implantation, in-stent restenosis is still encountered in a significant number of patients, particularly as increasingly complex lesions are tackled by percutaneous coronary intervention. Many biological and mechanical factors interplay to produce restenosis, some of which are avoidable. Intravascular imaging provided unique insights into various forms of stent-related mechanical issues that contribute to this phenomenon. From a practical perspective, intravascular imaging can therefore help to optimize the stenting procedure to avert these issues. Moreover, once the problem of restenosis eventuates, imaging can guide the management by tackling the underlying identified mechanism. Finally, it can be used to evaluate the re-intervention results. Nevertheless, with the emergence of different treatment options, more evidence is needed to define patient/lesion-specific characteristics that may help to tailor treatment selection in a way that improves clinical outcomes.

External elastic lamina vs. luminal diameter measurement for determining stent diameter by optical coherence tomography: an ILUMIEN III substudy

AIMS

Optical coherence tomography (OCT)-guided external elastic lamina (EEL)-based stent sizing is safe and as effective as intravascular ultrasound in achieving post-procedural lumen dimensions. However, when compared with automated lumen diameter (LD) measurements, this approach is time-consuming. We aimed to compare vessel diameter measurements and stent diameter selection using either of these approaches and examined whether applying a correction factor to automated LD measurements could result in selecting similar stent diameters to the EEL-based approach.

METHODS AND RESULTS

We retrospectively compared EEL-based measurements vs. automated LD in reference segments in 154 OCT acquisitions and derived a correction factor for stent sizing using the ratio of EEL to LD measurements. We then prospectively applied the correction factor in 119 OCT acquisitions. EEL could be adequately identified in 100 acquisitions (84%) at the distal reference to allow vessel diameter measurement. Vessel diameters were larger with EEL-based vs. LD measurements at both proximal (4.12 ± 0.74 vs. 3.14 ± 0.67 mm, P < 0.0001) and distal reference segments (3.34 ± 0.75 vs. 2.64 ± 0.65 mm, P < 0.0001). EEL-based downsizing led to selection of larger stents vs. an LD-based upsizing approach (3.33 ± 0.47 vs. 2.70 ± 0.44, P < 0.0001). Application of correction factors to LD [proximal 1.32 (IQR 1.23-1.37) and distal 1.25 (IQR 1.19-1.36)] resulted in discordance in stent sizing by >0.25 mm in 63% and potentially hazardous stent oversizing in 41% of cases.

CONCLUSION

EEL-based stent downsizing led to selection of larger stent diameters vs. LD upsizing. While applying a correction factor to automated LD measurements resulted in similar mean diameters to EEL-based measurements, this approach cannot be used clinically due to frequent and potentially hazardous stent over-sizing.

Stent Expansion Indexes to Predict Clinical Outcomes: An IVUS Substudy From ADAPT-DES

OBJECTIVES

The aim of this study was to evaluate various stent expansion indexes to determine the best predictor of clinical outcomes.

BACKGROUND

Numerous intravascular ultrasound (IVUS) studies have shown minimum stent area (MSA) to be the most powerful predictor of future events.

METHODS

ADAPT-DES (Assessment of Dual Antiplatelet Therapy With Drug-Eluting Stents) was a prospective, multicenter registry of 8,582 patients undergoing percutaneous coronary intervention (PCI) with drug-eluting stents. Native coronary artery lesions treated with IVUS-guided PCI with final analyzable IVUS were included. Ten stent expansion indexes (MSA, MSA/vessel area at MSA site, conventional stent expansion [MSA/average of proximal and distal reference luminal area], minimum stent expansion using Huo-Kassab or linear model accounting for vessel tapering, stent asymmetry [minimum/maximum stent diameter within the entire stent], stent eccentricity [smallest minimum/maximum stent diameter at a single slice within the stent], IVUS-XPL [Impact of intravascular Ultrasound Guidance on Outcomes of Xience Prime Stents in Long Lesions] criteria, ULTIMATE [Intravascular Ultrasound Guided Drug Eluting Stents Implantation in "All-Comers" Coronary Lesions] criteria, and ILUMIEN IV criteria) were evaluated for their associations with lesion-specific 2-year clinically driven target lesion revascularization (TLR) or definite stent thrombosis.

RESULTS

Overall, 2,140 lesions in 1,831 patients were included; final MSA measured 6.2 ± 2.4 mm². Among the 10 stent expansion indexes, only MSA/vessel area at the MSA site was independently associated with 2-year clinically driven TLR or definite stent thrombosis (hazard ratio: 0.77; 95% confidence interval: 0.59-0.99; P = 0.04) after adjusting for morphologic and procedural parameters.

CONCLUSIONS

In this IVUS-guided PCI cohort with excellent final MSA overall, stent/vessel area at the MSA site, an index of relative stent expansion, was superior to absolute MSA and other expansion indexes in predicting 2-year clinically driven TLR or definite stent thrombosis.

Optical coherence tomography-guided coronary stent implantation compared to angiography: a multicentre randomised trial in PCI - design and rationale of ILUMIEN IV: OPTIMAL PCI

AIMS

Randomised trials have demonstrated improvement in clinical outcomes with intravascular ultrasound (IVUS)-guided percutaneous coronary intervention (PCI) compared with angiography-guided PCI. The ILUMIEN III trial demonstrated non-inferiority of an optical coherence tomography (OCT)- versus IVUS-guided PCI strategy in achieving similar post-PCI lumen dimensions. ILUMIEN IV is a large-scale, multicentre, randomised trial designed to demonstrate the superiority of OCT- versus angiography-guided stent implantation in patients with high-risk clinical characteristics (diabetes) and/or complex angiographic lesions in achieving larger post-PCI lumen dimensions and improving clinical outcomes.

METHODS AND RESULTS

ILUMIEN IV is a prospective, single-blind clinical investigation that will randomise between 2,490 and 3,656 patients using an adaptive design to OCT-guided versus angiography-guided coronary stent implantation in a 1:1 ratio. The primary endpoints are: (1) post-PCI minimal stent area assessed by OCT in each randomised arm, and (2) target vessel failure, the composite of cardiac death, target vessel myocardial infarction, or ischaemia-driven target vessel revascularisation. Clinical follow-up will continue for up to two years. The trial is currently enrolling, and the principal results are expected in 2022.

CONCLUSIONS

The large-scale ILUMIEN IV randomised controlled trial will evaluate the effectiveness of OCT-guided versus angiography-guided PCI in improving post-PCI lumen dimensions and clinical outcomes in patients with diabetes and/or with complex coronary lesions.

TRIAL REGISTRATION

NCT03507777.

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.

When to use intravascular ultrasound or optical coherence tomography during percutaneous coronary intervention?

Intravascular ultrasound (IVUS) and optical coherence tomography (OCT) are intravascular imaging technologies widely used in the cardiac catheterization laboratory. The impact of these modalities for optimizing the acute and longer-term clinical impact following percutaneous coronary intervention (PCI) is supported by a wealth of clinical evidence. Intravascular imaging provides unique information for enhanced lesion preparation, optimal stent sizing, recognizing post PCI complications, and the etiology of stent failure. This review compares and contrasts the key aspects of these imaging modalities during PCI.

Fundamentals and role of intravascular ultrasound in percutaneous coronary intervention

Intravascular ultrasound (IVUS) is a catheter-based invasive imaging modality that has become an essential adjunctive tool to percutaneous coronary intervention (PCI) over the past 20 years. Clinical applications of IVUS in PCI include assessment of lesion severity, characterizing plaque morphology, optimization of acute stent results and clarification of mechanisms of stent failure. Numerous meta-analyses of large observational and randomized studies support the role of IVUS-guided PCI in reducing short and long-term adverse outcomes, including mortality and stent failure, particularly in patients receiving drug-eluting stents (DESs) and in complex lesion subsets. The current review provides a summary of the fundamental aspects and current clinical roles of IVUS in coronary intervention.

Balloon Angioplasty of Infrapopliteal Arteries: A Systematic Review and Proposed Algorithm for Optimal Endovascular Therapy

Endovascular revascularization has been increasingly utilized to treat patients with chronic limb-threatening ischemia (CLTI), particularly atherosclerotic disease in the infrapopliteal arteries. Lesions of the infrapopliteal arteries are the result of 2 different etiologies: medial calcification and intimal atheromatous plaque. Although several devices are available for endovascular treatment of infrapopliteal lesions, balloon angioplasty still comprises the mainstay of therapy due to a lack of purpose-built devices. The mechanism of balloon angioplasty consists of adventitial stretching, medial necrosis, and dissection or plaque fracture. In many cases, the diffuse nature of infrapopliteal disease and plaque complexity may lead to dissection, recoil, and early restenosis. Optimal balloon angioplasty requires careful attention to assessment of vessel calcification, appropriate vessel sizing, and the use of long balloons with prolonged inflation times, as outlined in a treatment algorithm based on this systematic review. Further development of specific devices for this arterial segment are warranted, including devices for preventing recoil (eg, dedicated atherectomy devices), treating dissections (eg, tacks, stents), and preventing neointimal hyperplasia (eg, novel drug delivery techniques and drug-eluting stents). Further understanding of infrapopliteal disease, along with the development of new technologies, will help optimize the durability of endovascular interventions and ultimately improve the limb-related outcomes of patients with CLTI.

Intravascular Ultrasound-guided Versus Angiography-guided Percutaneous Coronary Intervention: Evidence from Observational Studies and Randomized Controlled Trials

Coronary angiography has been considered the gold standard for the diagnosis of coronary artery disease and guidance of percutaneous coronary intervention (PCI). However, 2D-projection angiography cannot completely reflect the 3D coronary lumen. Intravascular ultrasound (IVUS) can overcome a number of limitations of coronary angiography by providing more information about the dimensions of the vessel lumen, plaque characteristics, stent deployment, and the mechanisms of device failure. Growing data from observational studies and randomized controlled trials have confirmed the clinical benefit of IVUS guidance during PCI. This article summarizes the evidence regarding IVUS guidance to highlight its advantages and to support the use of IVUS during PCI.

Rational and design of the European randomized Optical Coherence Tomography Optimized Bifurcation Event Reduction Trial (OCTOBER)

Background

Percutaneous coronary intervention in complex bifurcation lesions is prone to suboptimal implantation results and is associated with increased risk of subsequent clinical events. Angiographic ambiguity is high during bifurcation stenting, but it is unknown if procedural guidance by intravascular optical coherence tomography (OCT) improves clinical outcome.

Methods and Design

OCTOBER is a randomized, investigator-initiated, multicenter trial aimed to show superiority of OCT-guided stent implantation compared to standard angiographic-guided implantation in bifurcation lesions. The primary outcome measure is a 2-year composite end point of cardiac death, target lesion myocardial infarction, and ischemia-driven target lesion revascularization. The calculated sample size is 1,200 patients in total, and allocation is 1:1. Eligible patients have stable or unstable angina pectoris or stabilized non–ST elevation myocardial infarction, and a coronary bifurcation lesion with significant main vessel stenosis and more than 50 % stenosis in a side branch with a reference diameter ≥2.5mm. Treatment is performed by the provisional side branch stenting technique or 2-stent techniques, and the systematic OCT guiding protocol is aimed to evaluate (1) plaque preparation, (2) lesion length, (3) segmental reference sizes, (4) lesion coverage, (5) stent expansion, (6) malapposition, (7) wire positions, and (8) ostial results.

Implications

A positive outcome of the OCTOBER trial may establish OCT as a routine tool for optimization of complex percutaneous coronary intervention, whereas a negative result would indicate that OCT remains a tool for ad hoc evaluation in selected cases.

IVUS-Guided Versus OCT-Guided Coronary Stent Implantation: A Critical Appraisal

Procedural guidance with intravascular ultrasound (IVUS) imaging improves the clinical outcomes of patients undergoing percutaneous coronary intervention (PCI) by: 1) informing the necessity for lesion preparation; 2) directing appropriate stent sizing to maximize the final stent area and minimize geographic miss; 3) selecting the optimal stent length to cover residual disease adjacent to the lesion, thus minimizing geographic miss; 4) guiding optimal stent expansion; 5) identifying acute complications (edge dissection, stent malapposition, tissue protrusion); and 6) clarifying the mechanism of late stent failure (stent thrombosis, neointimal hyperplasia, stent underexpansion or fracture, or neoatherosclerosis). Optical coherence tomography (OCT) provides similar information to IVUS (with some important differences), also potentially improving acute and long-term patient outcomes compared to angiography-guided PCI. The purpose of this review is to describe the similarities and differences between IVUS and OCT technologies, and to highlight the evidence supporting their utility to improve PCI outcomes.

Effect of routine postdilatation on final coronary blood flow in primary percutaneous coronary intervention patients without angiographic stent expansion problems

Inadequate expansion of coronary stents is associated with stent thrombosis in early stage and with stent restenosis in later stages. Postdilatation (postD) performed using non-compliant balloons improves stent expansion. However, use of this ballooning strategy in primary percutaneous coronary intervention (PPCI) has not been evaluated adequately. Patients who presented with ST segment elevation myocardial infarction (STEMI) and underwent PPCI were included in the present study. Patients were randomized into two groups as those for whom postD was performed (n=62) and those for whom postD was not performed (n=62). Coronary blood flow was evaluated using the thrombolysis in myocardial infarction (TIMI) flow and TIMI frame count (TFC). Total of 124 patients with STEMI were included in the study. There was no difference with respect to baseline TIMI flow, culprit coronary artery and MI localization. However, slow-reflow rate (14.5% vs 35.5%, p=0.007) and final corrected TFC (28.9±16.9 vs 37.0±23.1, p=0.028) were significantly higher in the postD group. Multivariate regression analysis showed postD as an independent variable for slow reflow (OR 11.566, 95% CI 1.633 to 81.908, p=0.014). In our study, routine postD during PPCI was found to be associated with an increased risk of slow reflow in patients without angiographic stent expansion problems.

Efficacy of kissing balloon inflation after provisional stenting in bifurcation lesions guided by intravascular ultrasound: short and midterm results of the J-REVERSE registry

AIMS

Our aim was to investigate the efficacy of the kissing balloon technique (KBT) in the provisional stenting of bifurcation lesions guided by intravascular ultrasound.

METHODS AND RESULTS

In the J-REVERSE registry, 300 non-left main bifurcation lesions in 299 patients were divided into two groups, KBT (n=163) and non-KBT (n=137). Patient and lesion characteristics were similar except for a higher prevalence of diabetic patients in the non-KBT group. The major adverse cardiac events (MACE) incidence at nine-month follow-up, including target lesion revascularisation, myocardial infarction, stent thrombosis, and death, was 6.3% in the KBT group versus 9.1% in the non-KBT group (p=0.47). Regardless of more SB dissection (10.5% vs. 1.5%, p=0.001), the KBT group obtained a greater luminal volume in the proximal main vessel (MV) (7.8±2.3 vs. 7.0±2.0 mm3/mm, p=0.006), maintained larger minimal lumen diameter at follow-up (2.73±0.43 vs. 2.63±0.39 mm, p=0.04), and demonstrated less binary side branch (SB) restenosis (9.7% vs. 21.0%, p=0.0004), which was beneficial for both true and non-true bifurcation lesions. Multivariate analysis showed the efficacy of KBT on SB restenosis (OR 0.28, 95% CI: 0.12-0.62, p=0.002).

CONCLUSIONS

Although the KBT increased SB dissection, it provided greater luminal gain in the proximal MV and SB with a similar MACE rate to non-KBT treatment up to nine-month follow-up.

Clinical outcomes in real-world patients with small vessel disease treated with XIENCE V® everolimus-eluting stents: one year results from the XIENCE V® USA condition of approval post-market study

OBJECTIVES

The purpose of this study was to evaluate the 1-year clinical outcomes of more complex XIENCE V USA real-world patients with small versus nonsmall vessel lesions.

BACKGROUND

Patients with small vessel lesions undergoing coronary stent placement are at higher risk of major adverse cardiac events. Improved safety and efficacy of XIENCE V everolimus eluting stents (EES) have been previously demonstrated in selected low-risk small vessel populations in randomized clinical trials.

METHODS

The XIENCE V USA study was a condition of approval, single-arm study in unselected real-world patients. Baseline and 1-year clinical outcomes were compared between XIENCE V USA patients who received a single 2.5 mm stent (small vessel group, N = 838) and patients implanted with a single >2.5 mm stent (non-small vessel group, N = 2,015). Mean reference vessel diameter was 2.55 ± 0.36 and 3.25 ± 0.46 mm in the small and non-small vessel groups, respectively (P < 0.001).

RESULTS

Small vessel group had more females, presented with a higher rate of diabetes, and had more complex lesion characteristics. The definite or probable ST rates analyzed using Kaplan-Meier method were low and not significantly different between the groups at 0.37 and 0.40% for the small and nonsmall vessel group (P = 0.88), respectively. The composite rate of cardiac death or MI was comparable at 4.5% for the small and 5.1% for the non-small vessel 1 groups (P = 0.57). The 1-year target lesion revascularization rate was also comparable in the small vessel group (3.8% vs. 3.0%, P = 0.35).

CONCLUSIONS

Despite gender difference, higher prevalence of diabetes and more complex lesions in the small vessel groups, the 1-year clinical outcomes were similar in both small and nonsmall vessel groups. These results demonstrate the therapeutic benefit of XIENCE V EES in a real-world all inclusive patient population with small vessel disease.

Overaggressive stent expansion without intravascular imaging: impact on restenosis

OBJECTIVE

Aggressive stent expansion is required for optimal strut apposition, but risk of stent deformation, fracture and subsequent restenosis is potentially greater when performed without intravascular imaging guidance. We investigated how frequently stents are 'overexpanded' and whether this correlates with restenosis.

DESIGN AND SETTING

Single-centre prospective database study at a high-volume tertiary university hospital.

PATIENTS

243 patients undergoing single-vessel stenting for de novo stenosis in 277 lesions. Exclusion criteria were bifurcational, graft or left main disease and intravascular imaging use. All had ischaemia-driven repeat coronary angiography up to 48 months later. Degree of stent overexpansion was the difference between nominal and final stent size.

RESULTS

Stents were expanded above nominal in 99% of cases and above rated burst pressure in 52%. Stents were expanded >20% above nominal in 12% of cases. Stents overexpanded by >20% were smaller (2.87 vs 3.19 mm), longer (24 vs 19 mm) and more often drug-eluting (53% vs 27%). Angiographic restenosis was observed in 80 lesions (29%). There was no correlation between degree of overexpansion and per cent angiographic restenosis across the whole group (R(2)=-0.01; p=0.09), in those with stent overexpansion >20% (p=0.31) or small stents <3 mm (p=0.71). Indeed, in the group with stent overexpansion >25%, the greater the overexpansion, the less the per cent angiographic restenosis (p=0.02).

CONCLUSIONS

In this real-world population undergoing non-complex percutaneous coronary intervention without intravascular imaging, any tendency to overaggressive stent expansion did not predispose at all to restenosis.

Optical coherence tomography versus intravascular ultrasound to evaluate coronary artery disease and percutaneous coronary intervention

OBJECTIVES

We compared intravascular ultrasound (IVUS) and 2 different generations of optical coherence tomography (OCT)-time-domain OCT (TD-OCT) and frequency-domain OCT (FD-OCT)-for the assessment of coronary disease and percutaneous coronary intervention (PCI) using stents.

BACKGROUND

OCT is a promising light-based intravascular imaging modality with higher resolution than IVUS. However, the paucity of data on OCT image quantification has limited its application in clinical practice.

METHODS

A total of 227 matched OCT and IVUS pull backs were studied. One hundred FD-OCT and IVUS pull backs in nonstented (n = 56) and stented (n = 44) vessels were compared. Additionally, 127 matched TD-OCT and IVUS images were compared in stented vessels.

RESULTS

FD-OCT depicted more severe native coronary disease than IVUS; minimal lumen area (MLA) was 2.33 ± 1.56 mm(2) versus 3.32 ± 1.92 mm(2), respectively (p < 0.001). Reference vessel dimensions were equivalent between FD-OCT and IVUS in both native and stented coronaries, but TD-OCT detected smaller reference lumen size compared with IVUS. Immediately post-PCI, in-stent MLAs were similar between FD-OCT and IVUS, but at follow-up, both FD-OCT and TD-OCT detected smaller MLAs than did IVUS, likely due to better detection of neointimal hyperplasia (NIH). Post-PCI malapposition and tissue prolapse were more frequently identified by FD-OCT.

CONCLUSIONS

FD-OCT generates similar reference lumen dimensions but higher degrees of disease severity and NIH, as well as better detection of malapposition and tissue prolapse compared with IVUS. First-generation TD-OCT was associated with smaller reference vessel dimensions compared with IVUS.

Conductance sizing balloon for measurement of peripheral artery minimal stent area

BACKGROUND

Because stent underdeployment occurs frequently, accurate minimal stent area (MSA) measurement during postdilatation is necessary. This study investigated the accuracy and repeatability for MSA determination using a novel conductance balloon (CB) catheter for peripheral vessels.

METHODS

The CB catheter is a standard balloon catheter that measures electrical conductance (ratio of current/voltage drop) in real-time during inflation, which directly relates to the balloon cross-sectional area through Ohm's law. CB measurements were made in 4- to 10-mm phantoms on the bench, ex vivo in stents fully deployed in diseased human peripheral arteries, and in vivo in stents fully deployed in peripheral vessels in six swine. CB measurement accuracy and repeatability were calculated and compared with the known dimension (bench phantoms) or with intravascular ultrasound (IVUS) measurement after stent deployment (ex vivo and in vivo).

RESULTS

CB measurements were highly accurate (error: 1.8% bench, 5% ex vivo, and 5% in vivo) and repeatable (error: 0.9% bench, 1.8% ex vivo, and 1.3% in vivo), with virtually no bias (average difference in measurements: -0.05 mm bench CB vs known phantom diameters, -0.06 mm ex vivo CB vs IVUS, and -0.11 mm in vivo CB vs IVUS).

CONCLUSIONS

The CB sizing capability can be integrated within a standard balloon catheter (two-in-one function) to provide accurate, real-time assessment of MSA to ensure full stent apposition rather than the use of pressure as a surrogate for size.

Compliance charts to guide non-complex small artery stenting: validation by quantitative coronary angiography

OBJECTIVE

To determine whether stent sizing derived from manufacturers' compliance charts provides a reasonable in vivo estimate of final minimum lumen diameter (MLD) when compared with quantitative coronary angiography (QCA).

DESIGN

Single-centre measurement comparison study.

SETTING

Tertiary referral university hospital.

PATIENTS

Fifty cases receiving a single stent for non-complex de novo stenosis were randomly selected from the percutaneous coronary intervention database of our high-volume centre. Restenosis, stent thrombosis, bifurcational disease, rotablation, left main or graft stenting, intravascular ultrasound or kissing balloon inflations were exclusion criteria.

MAIN OUTCOME MEASURES

Equality and limits of agreement (LOA) between compliance chart and QCA measurements of final MLD, especially focusing on patients with small stents<3 mm. The paired t test and Bland-Altman plots were used to compare measurements.

RESULTS

There was no significant difference between compliance chart-derived and QCA final MLD (n=50; mean -0.034 mm, SD 0.35, 95% CI -0.132 to +0.064; p=0.49), with reasonable Bland-Altman LOA between the two methods of assessing final MLD in the overall group (LOA -0.72 to +0.66 mm), as well as in the group of particular interest with Derived final MLD <3 mm (n=30; mean 0.019 mm, SD 0.27, 95% CI -0.082 to +0.119; p=0.71; LOA -0.52 to +0.56 mm).

CONCLUSIONS

Compliance charts provide an acceptable estimate of final MLD and are a reasonable guide to sizing during non-complex stenting, especially in small vessels <3 mm.

Impact of frequency-domain optical coherence tomography guidance for optimal coronary stent implantation in comparison with intravascular ultrasound guidance

BACKGROUND

Frequency-domain optical coherence tomography (FD-OCT) is a novel, high resolution intravascular imaging modality. Intravascular ultrasound (IVUS) is a widely used conventional imaging modality for achieving optimal stent deployment. The aim of this study was to evaluate the impact of FD-OCT guidance for coronary stent implantation compared with IVUS guidance.

METHODS AND RESULTS

A total of 70 patients with de novo coronary artery lesions and either unstable or stable angina pectoris were enrolled in this randomized study (optical coherence tomography [OCT] group: n=35, IVUS group: n=35). In the OCT group, stent implantation was performed under FD-OCT guidance alone and final stent expansion was evaluated by IVUS. In the IVUS group, conventional IVUS guidance was used and final stent apposition was evaluated by FD-OCT. There were no significant differences regarding the procedural, fluoroscopy time, and contrast volume. Although device and clinical success rates also were similar, the visibility of vessel border was significantly lower in the OCT group (P<0.05). Minimum and mean stent area and focal and diffuse stent expansion were smaller (6.1±2.2 mm versus 7.1±2.1 mm, 7.5±2.5 versus 8.7±2.4 mm, 64.7±13.7% versus 80.3±13.4%, 84.2±15.8% versus 98.8±16.5%, P<0.05, respectively), and the frequency of significant residual reference segment stenosis at the proximal edge was higher in the OCT group (P<0.05). Incomplete apposed struts in both groups were similar (P=0.34).

CONCLUSIONS

FD-OCT guidance for stent implantation was associated with smaller stent expansion and more frequent significant residual reference segment stenosis compared with conventional IVUS guidance.

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.

IVUS-Guided Stent Implantation to Improve Outcome: A Promise Waiting to be Fulfilled

The use of intravascular ultrasound (IVUS) to improve acute angiographic results was already shown in the prestent era. Various studies demonstrated the efficacy of IVUS in balloon sizing and estimating the extent of positive remodeling. With the introduction of drug-eluting stents (DES) the rate of restenosis has been significantly reduced but a new concern, the risk of stent thrombosis, has emerged. The association of stent underexpansion with stent thrombosis was observed for bare metal stents (BMS) and DES. Until now, the criteria for IVUS optimization used in different studies have relied on distal reference or on mean reference vessel for stent or postdilatation balloon sizing. Furthermore, an important recent innovation not available in previous studies is the use of noncompliant balloons to perform high pressure post-dilatation. Universal and easily applicable IVUS criteria for optimization of stent implantation as well as randomized studies on IVUS-guided DES implantation are necessary to minimize stent malapposition and underexpansion, which in turn can positively influence the rates of stent restenosis and thrombosis.

Clinical and angiographic comparison of everolimus-eluting and paclitaxel-eluting stents in small coronary arteries: a post hoc analysis of the SPIRIT III randomized trial

BACKGROUND

Drug-eluting stents with low late loss may be particularly beneficial in small coronary arteries. We therefore examined whether the everolimus-eluting stent is superior to the paclitaxel-eluting stent in patients treated with 2.5-mm stents in the SPIRIT III trial.

METHODS

The SPIRIT III trial was a prospective, multicenter, randomized (2:1; XIENCE V: TAXUS Express) trial in which 1002 patients were enrolled. One or more 2.5-mm stents were implanted in 160 patients in the XIENCE V arm, and 59 patients, in the TAXUS arm. Mean vessel diameter was 2.36 +/- 0.30 and 2.34 +/- 0.33 mm in the XIENCE V and TAXUS groups, respectively (P = .69).

RESULTS

At 9 months, XIENCE V compared to TAXUS reduced the rates of major adverse cardiac events (cardiac death, myocardial infarction, or ischemic target lesion revascularization) from 12.5% to 3.2% (P = .02) and target vessel failure (cardiac death, reinfarction, or ischemic target vessel revascularization) from 16.1% to 5.2% (P = .02), the differences being driven primarily by reductions in target lesion revascularization (12.5% vs 1.3%; P = .002). In-stent late loss was significantly reduced by XIENCE V when compared to TAXUS (0.54 +/- 0.74 vs 0.11 +/- 0.43 mm, P = .01), as was In-segment binary angiographic restenosis (20.8% vs 4.1%, P = .02).

CONCLUSIONS

In this post hoc analysis from the SPIRIT III trial, the XIENCE V 2.5-mm stent significantly reduced clinical and angiographic restenosis compared to the TAXUS 2.5-mm stent, further supporting the hypothesis that lower late loss is beneficial in small vessel disease.

Defining a new standard for IVUS optimized drug eluting stent implantation: the PRAVIO study

OBJECTIVES

Preliminary Investigation to the Angiographic Versus IVUS Optimization Trial is a single center prospective observational intravascular ultrasound (IVUS) guided stent implantation study assessing new criteria for optimal drug eluting stent (DES) deployment.

BACKGROUND

IVUS assessment of DES often reveals underexpansion and malapposition. Optimal stent deployment is currently poorly defined and previous criteria may not be suitable in long and complex lesions.

METHODS

Optimization was defined as achieving >/or 70% of the cross-sectional area (CSA) of the postdilation balloon. This criterion was applied in 113 complex lesions. The size of this balloon was calculated according to vessel media-to-media diameters at various sites inside the stented segment. The IVUS guided treated lesions were matched according to diabetes, vessel type, reference vessel diameter, minimum lumen diameter (MLD), and lesion length with a group of angiographic treated lesions to compare final MLD achieved.

RESULTS

Mean minimum stent CSA according to the postdilation balloon utilized was 4.62 mm(2), 6.26 mm(2), 7.87 mm(2), and 9.87 mm(2) for 2.5 mm, 3.0 mm, 3.5 mm, and 4 mm balloons, respectively. Final MLD (mm) was significantly larger in the IVUS compared to the angiographic-guided group (3.09 +/- 0.50 vs. 2.67 +/- 0.54; P < 0.0001). There were no procedural complications related to IVUS use.

CONCLUSIONS

We propose new IVUS criteria based on vessel remodeling that results in an increment in the final MLD, compared to angiographic guidance, which is much larger than any previously published study. This criterion seems to be safely achievable. A proposed randomized study (angiographic vs. IVUS optimization trial) has been launched to test these concepts.

A novel method of coronary stent sizing using intravascular ultrasound: Safety and clinical outcomes

OBJECTIVES

The use of intravascular ultrasound (IVUS) in guiding coronary stenting has increased in recent years. The feasibility, safety and clinical outcomes of a novel method of sizing coronary stents using IVUS have not been established. The main end points of the current study are the incidence of acute and short-term complications, and the need for target vessel revascularization at six months.

METHODS

Eighty-six patients underwent coronary stenting using IVUS imaging during the procedure. The optimal size of the stents was determined by using a novel method (the 'aggressive IVUS method'), ie, measuring the media-to-media dimensions of the coronary vessels at the site of the lesions using IVUS. A six-month follow-up chart review was performed following the initial stenting.

RESULTS

At six months, there were two noncardiac deaths in the group. There were no acute, subacute or late stent thromboses. Target vessel revascularization and major adverse cardiac event rates remained low - at 5.8% and 9.3%, respectively. The mean (± SD) IVUS-derived coronary stent size (3.89±0.98 mm) using the aggressive IVUS method was significantly different from the mean IVUS-derived coronary stent size (3.46±0.96 mm) using the 'traditional IVUS method'.

CONCLUSION

Aggressive sizing of the coronary stents by IVUS guidance is feasible and safe, and is associated with a favourable clinical outcome.

Does IVUS guidance of coronary interventions affect outcome? a prime example of the failure of randomized clinical trials

There has been a decline in the role of intravascular ultrasound (IVUS) guiding stenting. IVUS has lost favor with interventional cardiologists largely due to the emergence of drug eluting stents (DES). The advent of DES has lowered the need to maximize the final result due to the known low late-loss. This phenomenon has contributed to reduced interest in optimizing results with IVUS guidance. However, current concerns regarding stent thrombosis in relation to DES and its associated significant morbidity and mortality has once more focused attention on optimal stent deployment. Prior to DES, the evidence base was rather ambiguous, as some randomized and observational studies supported IVUS guided bare metal stent insertion in terms of reducing rates of restenosis and clinically driven target lesion revascularisation whereas others demonstrated no such benefit. As there is an additional cost and learning curve with IVUS, it has become difficult to justify its routine use. We present here a contemporary argument for the resurgence of IVUS optimized stent insertion. We also highlight deficiencies in previously adopted IVUS optimization criteria, which were based on distal and proximal lumen sizes. The new criteria proposed are based on vessel size at different segments of the stented area and therefore take advantage of vessel remodeling. The availability of high pressure, non-compliant balloons have made attainment of these new optimization targets possible without increasing the risk of complications. We hope to demonstrate this statement with the completion of the angiographically versus IVUS optimization (AVIO) study that soon will be initiated.

Volumetric intravascular ultrasound imaging to illustrate the extent of coronary plaque burden in type 2 diabetic patients

BACKGROUND

Although angiography is the gold standard for coronary imaging, its efficacy in outlining diffuse coronary atherosclerosis in diabetic patients remains questionable. We aimed to compare quantitative cineangiographic analysis (QCA) with three-dimensional intravascular ultrasound (IVUS) imaging in type 2 diabetic patients with coronary artery disease.

METHODS

IVUS runs of 104 significant coronary lesions in 88 diabetic patients were performed. Arterial remodeling index was calculated as vessel area at minimal lumen area divided by mean reference vessel area.

RESULTS

No difference between the two analysis modes was shown for lesion length and minimal lumen diameter, whereas a significant discrepancy between QCA and IVUS was found for diameter stenosis (10 +/- 9% vs. 41 +/- 8%; P<.001) and vessel diameter (3.01 +/- 0.66 vs. 4.53 +/- 0.70 mm; P<.001). A significant difference on arterial remodeling at lesion site was found between insulin-treated diabetic patients and non-insulin-treated diabetic patients (remodeling index: 0.98 +/- 0.16 vs. 1.07 +/- 0.21; P=.04).

CONCLUSIONS

Coronary angiographic diagnosis in diabetic patients may be distorted due to a large plaque burden over longer vessel segments and the resulting absence of plaque-free reference segments. This distortion was found to be more pronounced in QCA analysis requiring a reference diameter, whereas volumetric IVUS imaging illustrated coronary artery dimensions more accurately according to anatomic structures. Constrictive arterial remodeling was observed more frequently in type 2 diabetic patients treated with insulin.

Duration of development of symptomatic in-stent restenosis correlates with the stent-to-vessel-diameter ratio: an intravascular ultrasound study

OBJECTIVE

Several predictors for in-stent restenosis (ISR) have been defined by intravascular ultrasound (IVUS) assessment; however, there is a lack of data correlating IVUS parameters with the speed of development of ISR. This study aims to investigate the relation between the duration of development of symptomatic ISR and the relative stent diameter.

METHODS

A total of 46 lesions in 43 consecutive patients with symptomatic ISR were investigated by IVUS with the Endosonics system (Volcano Therapeutics Inc., Rancho Cardova, California, USA). Duration of development of symptomatic ISR was determined by the period of angiographic evidence for ISR. Early ISR was defined in case of occurrence before 6 months. Reference vessel diameter was assessed as mean diameter limited by the external elastic membrane. Relative stent diameter was defined by the stent-to-vessel-diameter ratio (SVDR).

RESULTS

Mean duration of symptomatic ISR was 10.3+/-11.5 months for all 46 lesions. Early ISR was observed in 25 lesions (54%). Multivariate analysis revealed SVDR as the only independent predictor for early ISR (P=0.0242). Significant correlation was observed between the duration of development of symptomatic ISR and SVDR (r=0.634, P<0.001). On the basis of the receiver operating curve analysis, relative stent diameter was defined as small when SVDR< or =0.90. Symptomatic ISR within stents of small relative diameter occurred significantly earlier (5.3+/-3.0 versus 16.7+/-15.0 months, P<0.001) and more frequently before 6 months (73 versus 30%, P=0.003) than in stents with SVDR>0.90.

CONCLUSIONS

This IVUS study revealed significant correlation between the duration of development of symptomatic ISR and SVDR, which was an independent predictor for early ISR. IVUS-guided stenting may avoid early ISR by adapting the stent diameter to the vessel diameter.

The pathophysiology and burden of restenosis

The introduction of percutaneous transluminal coronary angioplasty (PTCA) revolutionized the surgical treatment of coronary artery disease. However, despite increased surgical experience and technical breakthroughs, restenosis occurs in 30%-50% of patients undergoing simple balloon angioplasty and in 10%-30% of patients who receive an intravascular stent. Animal and human data indicate that restenosis is a response to injury incurred during PTCA. The need for reintervention in a high percentage of patients due to restenosis remains an important limitation to the long-term success of PTCA. Stenting reduces initial elastic recoil and limits negative arterial remodeling; however, bare-metal stents may promote intimal hyperplasia by eliciting an immune and proliferative response. Consistent with these data, clinical studies suggest that drug-eluting stents, coated with anti-inflammatory or antiproliferative agents, reduce the risk for restenosis. Stenting represents a considerable cost burden. Treatment strategy should focus on selective use of expensive drug-eluting stents in populations where they have been found to be more clinically effective than bare-metal stents--patients who are at high risk for restenosis or who develop restenosis with bare-metal stents. Recent studies suggest that the pharmacologic management of restenosis is now feasible. Together, the judicious use of stents and oral pharmacotherapy promise to reduce the risk for restenosis, even among high-risk patients.

Intravascular Ultrasound in the Current Percutaneous Coronary Intervention Era

The use of intravascular ultrasound (IVUS) in the cardiac catheterization laboratory has continued to evolve since its introduction nearly 15 years ago. In this review, the authors discuss the current strategies regarding the use of this imaging modality during percutaneous coronary interventions. Although routine IVUS guidance of interventions is unnecessary, the tomographic perspective provided by this modality can be very informative in selected cases. It remains unknown whether the use of emerging IVUS-based technologies such as elastography or spectral analysis is feasible for identification of vulnerable plaques.