Management of Coronary Stent Underexpansion

Coronary stent underexpansion is an important problem and limitation of percutaneous coronary intervention, adversely affecting both short- and long-term patient outcomes. Stent underexpansion occurs when a stent fails to expand adequately compared with the adjacent reference segment, resulting in inadequate luminal gain. Multiple studies suggest that stent underexpansion is associated with increased risks of in-stent restenosis, stent thrombosis, and myocardial infarction, resulting in recurrent symptoms, readmissions, repeat interventions, and increased mortality. Contributing factors for stent underexpansion include severe calcification, inadequate lesion preparation, suboptimal stent deployment, and preexisting in-stent restenosis. Calcific plaques, especially when present behind a previously implanted, underexpanded stent, pose a significant challenge for further stent optimization. These lesions are often resistant to high-pressure balloon dilatation and may require advanced techniques that carry increased risks of complications. Intravascular imaging modalities, such as intravascular ultrasound and optical coherence tomography, have emerged as essential tools in diagnosing and managing stent underexpansion. These techniques provide a more detailed evaluation of the vessel and previously implanted stent, enabling the clinician to understand the exact mechanism of stent failure, and assess plaque burden and morphology, which ultimately helps guide appropriate treatment strategies. Despite the clinical importance of stent underexpansion, there is currently no consensus on its optimal treatment, largely because of the absence of large prospective studies in this area. This comprehensive review aims to summarize the existing evidence, clinical experience, and treatment strategies for coronary stent underexpansion, with the goal of providing practical guidance to clinicians to help optimize percutaneous coronary intervention and patient outcomes.

Agreement and reproducibility between 3DStent vs. Optical Coherence Tomography for evaluation of stent area and diameter

3DStent is a novel rotational angiography imaging capable of 3D reconstruction and measuring stent area and diameter, without need for intravascular imaging. To compare 3DStent and OCT-derived stent area and diameter after PCI. Patients with de novo coronary lesions who underwent treatment with a single DES and evaluated by OCT and 3DStent were included. Stent area and diameter were measured by 3DStent, at abluminal, mid and endoluminal side and by OCT. From September 2023 to February 2024 six coronary lesions were analyzed. Post-PCI stent area measured by OCT was (mean ± standard deviation) 7.03 ± 2.85 mm2 and by 3DStent 9.41 ± 2.79 mm2, 7.21 ± 2.23 mm2 and 5.63 ± 1.83 mm2 at abluminal, mid and endoluminal side, respectively. Stent diameter by OCT was 2.93 ± 0.58 mm, and by 3DStent 3.27 ± 0.50 mm, 2.86 ± 0.49 mm and 2.52 ± 0.45 mm at abluminal, mid and endoluminal side, respectively. Significant correlation was observed between OCT and 3DStent in relation to stent area (Exp(B) 3.35, mean of difference 0.19 ± 1.01 mm2, 95%CI -1.80-2.17 mm2, p < 0.001) and diameter (Exp(B) 3.18, mean difference - 0.07 ± 0.18 mm, 95%CI -0.43-0.30 mm, p < 0.001), particularly when 3DStent measurements performed at the mid side. Very high reproducibility was demonstrated by intra- and inter-observer analysis (r = 0.92 and r = 0.93 respectively). 3DStent appears to be an easy and reproducible tool to assess post-PCI stent area and diameter as compared to OCT.

Optical coherence tomography predictors of clinical outcomes after stent implantation: the ILUMIEN IV trial

BACKGROUND AND AIMS

Observational registries have suggested that optical coherence tomography (OCT) imaging-derived parameters may predict adverse events after drug-eluting stent (DES) implantation. The present analysis sought to determine the OCT predictors of clinical outcomes from the large-scale ILUMIEN IV trial.

METHODS

ILUMIEN IV was a prospective, single-blind trial of 2487 patients with diabetes or high-risk lesions randomized to OCT-guided versus angiography-guided DES implantation. All patients underwent final OCT imaging (blinded in the angiography-guided arm). From more than 20 candidates, the independent OCT predictors of 2-year target lesion failure (TLF; the primary endpoint), cardiac death or target-vessel myocardial infarction (TV-MI), ischaemia-driven target lesion revascularization (ID-TLR), and stent thrombosis were analysed by multivariable Cox proportional hazard regression in single treated lesions.

RESULTS

A total of 2128 patients had a single treated lesion with core laboratory-analysed final OCT. The 2-year Kaplan-Meier rates of TLF, cardiac death or TV-MI, ID-TLR, and stent thrombosis were 6.3% (n = 130), 3.3% (n = 68), 4.3% (n = 87), and 0.9% (n = 18), respectively. The independent predictors of 2-year TLF were a smaller minimal stent area (per 1 mm2 increase: hazard ratio 0.76, 95% confidence interval 0.68-0.89, P < .0001) and proximal edge dissection (hazard ratio 1.77, 95% confidence interval 1.20-2.62, P = .004). The independent predictors of cardiac death or TV-MI were smaller minimal stent area and longer stent length; of ID-TLR were smaller intra-stent flow area and proximal edge dissection; and of stent thrombosis was smaller minimal stent expansion.

CONCLUSIONS

In the ILUMIEN IV trial, the most important OCT-derived post-DES predictors of both safety and effectiveness outcomes were parameters related to stent area, expansion and flow, proximal edge dissection, and stent length.

Impact of Lipidic Plaque on In-Stent and Stent Edge-Related Events After PCI in Myocardial Infarction: A PROSPECT II Substudy

BACKGROUND

Lipid content in untreated nonobstructive coronary artery lesions is associated with adverse clinical outcomes, and residual in-stent or stent edge lipid may worsen outcomes after percutaneous coronary intervention (PCI).

METHODS

Near-infrared spectroscopy-intravascular ultrasound was performed before and after PCI in patients with myocardial infarction. We evaluated the impact of lipid assessed by near-infrared spectroscopy (maximal lipid core burden index over 4 mm [maxLCBI4mm]) along with intravascular ultrasound information including residual plaque burden on in-stent or edge-related major adverse cardiac events (MACE) in de novo PCI-treated culprit coronary artery lesions. The primary end point was culprit lesion-related MACE (CL-MACE), defined as cardiac death, myocardial infarction, or unstable or progressive angina either requiring revascularization or with rapid lesion progression and classified as in-stent or stent edge-related.

RESULTS

During a median follow-up of 3.8 years, 25 CL-MACE (11 stent edge-related, 13 in-stent, and 1 in-lesion without a stent) occurred in 1041 PCI-treated lesions in 768 patients. Pre-PCI or post-PCI measures of lipid content were not related to in-stent CL-MACE. However, stent edge-related CL-MACE was increased if both the post-PCI stent edge maxLCBI4mm was greater than the upper quartile (108.7) and the stent edge plaque burden was >50% (adjusted odds ratio, 4.11 [95% CI, 1.12-15.2]; P=0.03).

CONCLUSIONS

In PROSPECT II (Providing Regional Observations to Study Predictors of Events in the Coronary Tree), CL stent implantation leaving behind greater stent edge-related lipid and uncovered plaque burden was associated with an increased risk of stent edge-related CL-MACE during follow-up. In contrast, CL lipid content was not related to in-stent CL-MACE.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT02171065.

Image-guided percutaneous revascularization of the coronary arteries

The European Society of Cardiology recently updated guidelines on the management of chronic coronary syndromes upgrading the use of intracoronary imaging for complex percutaneous coronary interventions (PCI) to a class 1A recommendation. It is essential that the interventional community appreciate the additive value of intracoronary imaging over angiography alone-not only to obtain optimal acute PCI results but also to improve longer-term cardiovascular outcomes. The purpose of this manuscript is to review the latest evidence that informed the recent guideline recommendations and expand on the specific role of the different imaging modalities before, during, and after PCI.

Artificial Intelligence for the Interventional Cardiologist: Powering and Enabling OCT Image Interpretation

Intravascular optical coherence tomography (IVOCT) is a form of intra-coronary imaging that uses near-infrared light to generate high-resolution, cross-sectional, and 3D volumetric images of the vessel. Given its high spatial resolution, IVOCT is well-placed to characterise coronary plaques and aid with decision-making during percutaneous coronary intervention. IVOCT requires significant interpretation skills, which themselves require extensive education and training for effective utilisation, and this would appear to be the biggest barrier to its widespread adoption. Various artificial intelligence-based tools have been utilised in the most contemporary clinical IVOCT systems to facilitate better human interaction, interpretation and decision-making. The purpose of this article is to review the existing and future technological developments in IVOCT and demonstrate how they could aid the operator.

Coronary Physiology as Part of a State-of-the-Art Percutaneous Coronary Intervention Strategy: Lessons from SYNTAX II and Beyond

The use of coronary physiology allows for rational decision making at the time of PCI, contributing to better patient outcomes. Yet, coronary physiology is only one aspect of optimal revascularization. State-of-the-art PCI must also consider other important aspects such as intracoronary imaging guidance and specific procedural expertise, as tested in the SYNTAX II study. In this review, we highlight the technical aspects pertaining to the use of physiology as used in that trial and offer a glimpse into the future with emerging physiologic metrics, including functional coronary angiography, which have already established themselves as useful indices to guide decision making.

Rotational atherectomy combined with cutting balloon to optimise stent expansion in calcified lesions: the ROTA-CUT randomised trial

BACKGROUND

Percutaneous coronary intervention (PCI) of calcified lesions remains challenging for interventionalists.

AIMS

We aimed to investigate whether combining rotational atherectomy (RA) with cutting balloon angioplasty (RA+CBA) results in more optimal stent expansion compared with RA followed by non-compliant balloon angioplasty (RA+NCBA).

METHODS

ROTA-CUT is a prospective, multicentre, randomised trial of 60 patients with coronary artery disease undergoing PCI of moderately or severely calcified lesions with drug-eluting stent implantation. Patients were randomised 1:1 to either RA+CBA or RA+NCBA. The primary endpoint was the minimum stent area on intravascular ultrasound (IVUS). Secondary endpoints included minimum lumen area and stent expansion assessed by IVUS and acute lumen gain, final residual diameter stenosis and minimum lumen diameter assessed by angiography. Clinical endpoints were obtained at 30 days.

RESULTS

The mean age was 71.1±9.4 years, and 22% were women. The procedural details of RA were similar between groups, as were procedure duration and contrast use. Minimum stent area was similar with RA+CBA versus RA+NCBA (6.7±1.7 mm2 vs 6.9±1.8 mm2; p=0.685). Furthermore, there were no significant differences regarding the other IVUS and angiographic endpoints. Procedural complications were rare, and 30-day clinical events included 2 myocardial infarctions and 1 target vessel revascularisation in the RA+CBA group and 1 myocardial infarction in the RA+NCBA group.

CONCLUSIONS

Combining RA with CBA resulted in a similar minimum stent area compared with RA followed by NCBA in patients undergoing PCI of moderately or severely calcified lesions. RA followed by CBA was safe with rare procedural complications and few clinical adverse events at 30 days.

Comparative treatment outcomes of a single long stent vs. overlapped short stents in acute myocardial infarction

Objectives

There is no consensus regarding the optimal choice between single long stent (SLS) and overlapped double short stents (DSS) in patients with acute myocardial infarction (AMI). Therefore, we aimed to compare treatment outcomes among patients with AMI treated with these two different stenting methods.

Methods

In total, 537 patients with AMI from a single tertiary center were categorized into two groups: (1) those who received an SLS (stent length ≥38 mm) (n = 254; 47.3%) and (2) those who received overlapped DSS (individual stent lengths <38 mm) (n = 283; 52.7%). The primary outcome was the incidence of major adverse cardiac and cerebrovascular events (MACCEs) within 1 year.

Results

The mean age of participants was 65.4 years, and 75.0% were male. Patients receiving an SLS had a higher rate of serum creatinine level ≥1.5 mg/dl (16.3% vs. 8.9%, p = 0.009) but a lower rate of hypertension (46.8% vs. 55.8%, p = 0.038), lesser total stent length (38.26 ± 1.31 vs. 45.20 ± 9.25 mm, p < 0.001), total procedure time (41.40 ± 15.74 vs. 53.31 ± 21.75 min, p < 0.001) and total contrast volume (134.13 ± 30.72 vs. 160.57 ± 39.77 ml, p < 0.001) than in those receiving DSS. One-year MACCEs were comparable between the two groups before [hazard ratio (HR), 1.33; 95% confidence interval (CI), 0.80-2.24] and after adjusting for covariates (HR, 1.21; 95% CI, 0.67-2.19).

Conclusions

Stenting with an SLS demonstrated similar outcomes compared to those achieved when using stenting with overlapped DSS in patients with AMI. Therefore, if the deliverability is acceptable, stenting with an SLS appears to be a safe and effective strategy for AMI treatment.

Comparison of the OPTIVUS-Complex PCI Multivessel Cohort With the Historical CREDO-Kyoto Registry Cohort-3

BACKGROUND

There is a paucity of data on the effect of optimal intravascular ultrasound (IVUS)-guided percutaneous coronary intervention (PCI) compared with standard PCI or coronary artery bypass grafting (CABG) in patients with multivessel disease.

METHODS AND RESULTS

The OPTIVUS-Complex PCI study multivessel cohort was a prospective multicenter single-arm study enrolling 1,021 patients undergoing multivessel PCI including the left anterior descending coronary artery using IVUS aiming to meet the prespecified criteria for optimal stent expansion. We conducted propensity score matching analyses between the OPTIVUS group and historical PCI or CABG control groups from the CREDO-Kyoto registry cohort-3 (1,565 and 899 patients) fulfilling the inclusion criteria for this study. The primary endpoint was a composite of death, myocardial infarction, stroke, or any coronary revascularization. In the propensity score-matched cohort (OPTIVUS vs. historical PCI control: 926 patients in each group; OPTIVUS vs. historical CABG control: 436 patients in each group), the cumulative 1-year incidence of the primary endpoint was significantly lower in the OPTIVUS group than in the historical PCI control group (10.4% vs. 23.3%; log-rank P<0.001) or the historical CABG control group (11.8% vs. 16.5%; log-rank P=0.02).

CONCLUSIONS

IVUS-guided PCI targeting the OPTIVUS criteria combined with contemporary clinical practice was associated with superior clinical outcomes at 1 year compared with not only the historical PCI control, but also the historical CABG control.

Optical Coherence Tomography-Guided versus Angiography-Guided PCI

BACKGROUND

Data regarding clinical outcomes after optical coherence tomography (OCT)-guided percutaneous coronary intervention (PCI) as compared with angiography-guided PCI are limited.

METHODS

In this prospective, randomized, single-blind trial, we randomly assigned patients with medication-treated diabetes or complex coronary-artery lesions to undergo OCT-guided PCI or angiography-guided PCI. A final blinded OCT procedure was performed in patients in the angiography group. The two primary efficacy end points were the minimum stent area after PCI as assessed with OCT and target-vessel failure at 2 years, defined as a composite of death from cardiac causes, target-vessel myocardial infarction, or ischemia-driven target-vessel revascularization. Safety was also assessed.

RESULTS

The trial was conducted at 80 sites in 18 countries. A total of 2487 patients underwent randomization: 1233 patients were assigned to undergo OCT-guided PCI, and 1254 to undergo angiography-guided PCI. The minimum stent area after PCI was 5.72±2.04 mm2 in the OCT group and 5.36±1.87 mm2 in the angiography group (mean difference, 0.36 mm2; 95% confidence interval [CI], 0.21 to 0.51; P<0.001). Target-vessel failure within 2 years occurred in 88 patients in the OCT group and in 99 patients in the angiography group (Kaplan-Meier estimates, 7.4% and 8.2%, respectively; hazard ratio, 0.90; 95% CI, 0.67 to 1.19; P = 0.45). OCT-related adverse events occurred in 1 patient in the OCT group and in 2 patients in the angiography group. Stent thrombosis within 2 years occurred in 6 patients (0.5%) in the OCT group and in 17 patients (1.4%) in the angiography group.

CONCLUSIONS

Among patients undergoing PCI, OCT guidance resulted in a larger minimum stent area than angiography guidance, but there was no apparent between-group difference in the percentage of patients with target-vessel failure at 2 years. (Funded by Abbott; ILUMIEN IV: OPTIMAL PCI ClinicalTrials.gov number, NCT03507777.).

Impact of Stent Expansion Index on Stent Failure After Left Main Stenting

Impact of the stent expansion index (EXPI) in percutaneous coronary intervention (PCI) for unprotected left main distal bifurcation lesions (ULMD) has been not completely understood especially in current-generation drug-eluting stent (cDES) era. We evaluated the impact of EXPI on clinical outcomes after PCI with cDES for ULMD. We identified 342 patients treated with cDES for ULMD and postintervention intravascular ultrasound between January 2010 and December 2019. In this study, the ratio of minimum stent area (MSA) to reference vessel area at the MSA site was adopted to assess the stent expansion. We defined the patients with the first and second tertile as low-intermediate EXPI group and those with the third tertile as high EXPI group and compared the clinical outcomes between both groups. The primary end point was target lesion failure (TLF). TLF was defined as a composite of cardiac death, target lesion revascularization (TLR) ,and myocardial infarction. The MSA was located in the ostium of left anterior descending coronary artery in most cases (318 of 342 patients; 93.0%). There were no significant differences between both groups in the baseline clinical, lesion, and procedural characteristics. The high EXPI group had lower TLF rate than the low-intermediate EXPI group (10.2% vs 19.9%, log-rank p = 0.033). In conclusion, this is the first report that the higher ratio of MSA to reference vessel area at the MSA site, which was defined as stent EXPI, was associated with more favorable clinical outcomes after PCI for ULMD.

Ultrathin-strut vs thin-strut drug-eluting stents for multi and single-stent lesions: A lesion-level subgroup analysis of 2 randomized trials

BACKGROUND

Whether ultrathin-strut stents are particularly beneficial for lesions requiring implantation of more than 1 stent is unknown.

METHODS

In a post-hoc lesion-level analysis of 2 randomized trials comparing ultrathin-strut biodegradable polymer Sirolimus-eluting stents (BP-SES) vs thin-strut durable polymer Everolimus-eluting stents (DP-EES), lesions were stratified into multistent lesions (MSL) vs single-stent lesions (SSL). The primary endpoint was target lesion failure (TLF), a composite of lesion-related unclear/cardiac death, myocardial infarction (MI), or revascularization, at 24 months.

RESULTS

Among 5328 lesions in 3397 patients, 1492 (28%) were MSL (722 with BP-SES, 770 with DP-EES). At 2 years, TLF occurred in 63 lesions (8.9%) treated with BP-SES and 60 lesions (7.9%) treated with DP-EES in the MSL-group (subdistibution hazard ratio [SHR], 1.13; 95% CI, 0.77-1.64; P = .53), and in 121 (6.4%) and 136 (7.4%) lesions treated with BP-SES and DP-EES respectively (SHR, 0.86; 95% CI, 0.62-1.18; P = .35) in the SSL-group (P for interaction = .241). While the rates of lesion-related MI or revascularization were significantly lower in SSL treated with BP-SES as compared to DP-EES (3.5% vs 5.2%; SHR, 0.67; 95% CI 0.46-0.97; P = .036), no significant difference was observed in MSL (7.1% vs 5.4%; SHR, 1.31; 95% CI 0.85-2.03; P = .216) with significant interaction between groups (P for interaction = .014).

CONCLUSIONS

Rates of TLF are similar between ultrathin-strut BP-SES and thin-strut DP-EES in MSL and SSL. The use of ultrathin-strut BP-SES vs thin-strut DP-EES did not prove to be particularly beneficial for the treatment of multistent lesions.

TRIAL REGISTRATION

Post-hoc analysis from the BIOSCIENCE (NCT01443104) and BIOSTEMI (NCT02579031) trials.

Accuracy of IVUS-Based Machine Learning Segmentation Assessment of Coronary Artery Dimensions and Balloon Sizing

Background

Accurate intravascular ultrasound (IVUS) measurements are important in IVUS-guided percutaneous coronary intervention optimization by choosing the appropriate device size and confirming stent expansion.

Objectives

The purpose of this study was to assess the accuracy of machine learning (ML) automatic segmentation of coronary artery vessel and lumen dimensions and balloon sizing.

Methods

Using expert analysis as the gold standard, ML segmentation of 60 MHz IVUS images was developed using 8,076 IVUS cross-sectional images from 234 patients, which were randomly split into training (83%) and validation (17%) data sets. The performance of ML segmentation was then evaluated using an independent test data set (437 images from 92 patients). The endpoints were the agreement rate between ML vs experts' measurements for appropriate balloon size selection, and lumen and acute stent areas. Appropriate balloon size was determined by rounding down from the mean vessel diameter or rounding up from the mean lumen diameter to the next balloon size. The difference of lumen area ≥0.5 mm2 was considered as clinically significant.

Results

ML model segmentation correlated well with experts' segmentation for training data set with a correlation coefficient of 0.992 and 0.993 for lumen and vessel areas, respectively. The agreement rate in lumen and acute stent areas was 85.5% and 97.0%, respectively. The agreement rate for appropriate balloon size selection was 70.6% by vessel diameter only and 92.4% by adding lumen diameter.

Conclusions

ML model IVUS segmentation measurements were well-correlated with those of experts and selected an appropriate balloon size in more than 90% of images.

Target Lesion Revascularization After Intravascular Ultrasound-Guided Percutaneous Coronary Intervention

BACKGROUND

Several stent expansion criteria derived from the intravascular ultrasound (IVUS) evaluation have been proposed to predict future clinical outcomes, but optimal stent expansion criteria as a guide during percutaneous coronary intervention (PCI) are still controversial. There are no studies evaluating the utility of stent expansion criteria along with the clinical and procedural factors in predicting target lesion revascularization (TLR) after contemporary IVUS-guided PCI.

METHODS

OPTIVUS-Complex PCI study (Optimal Intravascular Ultrasound Guided Complex Percutaneous Coronary Intervention) multivessel cohort was a prospective multicenter study enrolling 961 patients undergoing multivessel PCI including left anterior descending coronary artery using IVUS with an intention to meet the prespecified criteria for optimal stent expansion. We compared several stent expansion criteria (minimum stent area [MSA], MSA/distal or average reference lumen area, MSA/distal or average reference vessel area, OPTIVUS criteria, 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 modified MUSIC [Multicenter Ultrasound Stenting in Coronaries Study] criteria) as well as clinical, angiographic, and procedural characteristics between lesions with and without TLR.

RESULTS

Among 1957 lesions, the cumulative 1-year incidence of lesion-based TLR was 1.6% (30 lesions). Hemodialysis, treatment of proximal left anterior descending coronary artery lesions, calcified lesions, small proximal reference lumen area, and small MSA had univariate associations with TLR, while all of the stent expansion criteria except for MSA were not associated with TLR. The independent risk factors of TLR were calcified lesions (hazard ratio, 2.34 [95% CI, 1.03-5.32]; P=0.04) and small proximal reference lumen area (Tertile 1: hazard ratio, 7.01 [95% CI, 1.45-33.93]; P=0.02; and Tertile 2: hazard ratio, 5.40 [95% CI, 1.17-24.90]; P=0.03).

CONCLUSIONS

In contemporary IVUS-guided PCI practice, the 1-year incidence of TLR was very low. MSA, but not other stent expansion criteria, had univariate association with TLR. Independent risk factors of TLR were calcified lesions and small proximal reference lumen area, although the findings should be interpreted with caution due to small number of TLR events, limited lesion complexity, and short duration of follow-up.

Optical Coherence Tomography-Guided Percutaneous Coronary Intervention: Practical Application

Optical coherence tomography (OCT) provides high-resolution imaging of coronary arteries and can be used to optimize percutaneous coronary intervention (PCI). Intracoronary OCT, however, has had limited adoption in clinical practice. Novelty and relative complexity of OCT interpretation compared with the more established intravascular ultrasound, lack of a standardized algorithm for PCI guidance, paucity of data from randomized trials, and lack of rebate for intravascular imaging have contributed to the modest practical adoption of OCT. We provide a practical step-by-step guide on how to use OCT in PCI, including device set-up, simplified image interpretation, and an algorithmic approach for PCI. optimization.

Coronary Physiology as Part of a State-of-the-Art Percutaneous Coronary Intervention Strategy: Lessons from SYNTAX II and Beyond

The use of coronary physiology allows for rational decision making at the time of PCI, contributing to better patient outcomes. Yet, coronary physiology is only one aspect of optimal revascularization. State-of-the-art PCI must also consider other important aspects such as intracoronary imaging guidance and specific procedural expertise, as tested in the SYNTAX II study. In this review, we highlight the technical aspects pertaining to the use of physiology as used in that trial and offer a glimpse into the future with emerging physiologic metrics, including functional coronary angiography, which have already established themselves as useful indices to guide decision making.

Impact of trans-stent gradient on outcome after PCI: results from a HAWKEYE substudy

To test whether quantitative flow ratio (QFR)-based trans-stent gradient (TSG) is associated with adverse clinical events at follow-up. A post-hoc analysis of the multi-center HAWKEYE study was performed. Vessels post-PCI were divided into four groups (G) as follows: G1: QFR ≥ 0.90 TSG = 0 (n = 412, 54.8%); G2: QFR ≥ 0.90, TSG > 0 (n = 216, 28.7%); G3: QFR < 0.90, TSG = 0 (n = 37, 4.9%); G4: QFR < 0.90, TSG > 0 (n = 86, 11.4%). Cox proportional hazards regression model was used to analyze the effect of baseline and prognostic variables. The final reduced model was obtained by backward stepwise variable selection. Receiver operating characteristic (ROC) was plotted and area under the curve (AUC) was calculated and reported. Overall, 449 (59.8%) vessels had a TSG = 0 whereas (40.2%) had TSG > 0. Ten (2.2%) vessel-oriented composite endpoint (VOCE) occurred in vessels with TSG = 0, compared with 43 (14%) in vessels with TSG > 0 (p < 0.01). ROC analysis showed an AUC of 0.74 (95% CI: 0.67 to 0.80; p < 0.001). TSG > 0 was an independent predictor of the VOCE (HR 2.95 [95% CI 1.77–4.91]). The combination of higher TSG and lower final QFR (G4) showed the worst long-term outcome while low TSG and high QFR showed the best outcome (G1) while either high TSG or low QFR (G2, G3) showed intermediate and comparable outcomes. Higher trans-stent gradient was an independent predictor of adverse events and identified a subgroup of patients at higher risk for poor outcomes even when vessel QFR was optimal (> 0.90).

Impact of Intravascular Ultrasound-Guided Optimal Stent Expansion on 3-Year Hard Clinical Outcomes

[Figure: see text].

Long-term (beyond 5 years) clinical impact of Xience everolimus-eluting stent implantation

OBJECTS

We aim at examining the long-term clinical outcome after Xience everolimus-eluting stent (X-EES) implantation.

BACKGROUND

Long-term clinical outcomes beyond 5 years after X-EES implantation remain unclear.

METHODS

This retrospective study has collected data from 1184 consecutive patients, corresponding to 1463 lesions, who were treated with X-EES alone in the Nagoya Heart Center between January 2010 and December 2013. The primary endpoint was the 10-year cumulative incidence of target lesion failure (TLF), defined as cardiac death, target vessel myocardial infarction (MI), and clinically indicated target lesion revascularization (TLR). Definite/probable stent thrombosis (ST) was evaluated as a secondary outcome.

RESULTS

At 10 years, the cumulative incidence of TLF was recorded to be 12.4%, whereas that of cardiac death, target vessel MI, and clinically indicated TLR was at 4.4%, 4.1%, and 7.8%, respectively. The cumulative rate of definite/probable ST was observed to remain low (0.3% at 30 days; 0.3% at 1 year; 0.6% at 5 years; and 1.1% at 10 years). In the multivariate analysis, the risk factors of TLF were insulin-treated diabetes (hazard ratio (HR), 1.93; 95% confidence interval (CI), 1.13-3.29; P = .02), left ventricular dysfunction (HR, 2.28; 95% CI, 1.43-3.62; P < .01), hemodialysis (HR, 2.22; 95% CI, 1.39-3.56; P < .01), prior percutaneous coronary intervention (HR, 1.68; 95% CI, 1.18-2.41; P < .01), peripheral vascular disease (HR, 1.70; 95% CI, 1.07-2.69; P < .01), severe calcification (HR, 2.08; 95% CI, 1.36-3.09; P < .01), and in-stent restenosis (HR, 2.93; 95% CI, 1.64-4.89; P < .01).

CONCLUSIONS

The incidence rates of the long-term adverse effects after X-EES implantation, such as late TLR and ST, were determined to be low in this study; however, they increased over time until 10 years after stent implantation.

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.

Intracoronary optical coherence tomography: state of the art and future directions

Optical coherence tomography (OCT) has been increasingly utilised to guide percutaneous coronary intervention (PCI). Despite the diagnostic utility of OCT, facilitated by its high resolution, the impact of intracoronary OCT on clinical practice has thus far been limited. Difficulty in transitioning from intravascular ultrasound (IVUS), complex image interpretation, lack of a standardised algorithm for PCI guidance, and paucity of data from prospective clinical trials have contributed to the modest adoption. Herein, we provide a comprehensive up-do-date overview on the utility of OCT in coronary artery disease, including technical details, device set-up, simplified OCT image interpretation, recognition of the imaging artefacts, and an algorithmic approach for using OCT in PCI guidance. We discuss the utility of OCT in acute coronary syndromes, provide a summary of the clinical trial data, list the work in progress, and discuss the future directions.

Optimization of Percutaneous Coronary Intervention Using Optical Coherence Tomography

Compared to the luminogram obtained by angiography, intravascular modalities produce cross-sectional images of coronary arteries with a far greater spatial resolution. It is capable of accurately determining the vessel size and plaque morphology. It also eliminates some disadvantages such as contrast streaming, foreshortening, vessel overlap, and angle dependency inherent to angiography. Currently, the development of its system and the visualization of coronary arteries has shown significant advancement. Of those, optical coherence tomography (OCT) makes it possible to obtain high-resolution images of intraluminal and transmural coronary structures leading to navigation of the treatment strategy before and after stent implantations. The aim of this review is to summarize the published data on the clinical utility of OCT, focusing on the use of OCT in interventional cardiology practice to optimize percutaneous coronary intervention.