Impact of target lesion calcification on coronary stent expansion after rotational atherectomy

Long-term outcomes following intravascular lithotripsy (IVL) for calcified coronary lesions: A Real-World Multicenter European Study

OBJECTIVES

To explore the long-term clinical outcomes following intravascular lithotripsy (IVL) in calcified coronary lesions from a real-world population.

BACKGROUND

IVL is a relatively new but promising modality for treating coronary calcified lesions, but there is a dearth of long-term outcome data from real-world patients.

METHODS

This was a multicenter, observational study in which we enrolled all patients treated with IVL from November 2018 to February 2021 from eight centers in Europe and the United Kingdom. Procedural success, complications, and clinical outcomes (cardiac death, target vessel myocardial infarction [TVMI], target lesion revascularization [TLR], and MACE [major adverse cardiac events, the composite of cardiac death, TVMI, and TLR]) were assessed.

RESULTS

In total, 273 patients with a mean age of 72 ± 9.1 years were treated with IVL. Major comorbidities included diabetes mellitus (n = 110, 40%) and chronic kidney disease (n = 45, 16%). Acute coronary syndrome accounted for 48% (n = 132) of patients, while 52% (n = 141) had stable angina. De novo lesions and in-stent restenosis accounted for 79% and 21% of cases, respectively. Intravascular imaging was used in 33% (n = 90) of patients. An upfront IVL strategy was adopted in 34% (n = 92), while the rest were bailout procedures. Adjuvant rotational atherectomy ("RotaTripsy") was required in 11% (n = 31) of cases. The procedural success was 99%. During a median follow-up of 687 days (interquartile range: 549-787), cardiac death occurred in 5% (n = 14), TVMI in 3% (n = 8), TLR in 6% (n = 16), and MACE rate was 11% (n = 30).

CONCLUSION

This is the largest multicenter registry with a long-term follow-up showing the remarkably high procedural success of IVL use in calcified coronary lesions with low rates of hard endpoints and MACE.

Clinical Outcomes of Rotational Atherectomy in Heavily Calcified Lesions: Evidence From the Largest Cardiac Center in Thailand

Background

Evidence regarding the clinical outcomes of rotational atherectomy (RA) in middle-income countries is limited. We analyzed the clinical outcomes of patients with heavily calcified coronary lesions who underwent RA-assisted percutaneous coronary intervention (PCI) and explored the risks for developing major adverse cardiovascular and cerebrovascular events (MACCE).

Methods

This is a single-center, retrospective cohort analysis that enrolled consecutive patients who underwent RA-assisted PCI at the largest tertiary hospital in Thailand. The primary endpoint is the incidence of MACCE during the first-year follow-up. MACCE consists of cardiac death, ischemic stroke, definite stent thrombosis, target lesion revascularization, and target vessel revascularization.

Results

From January 2015 to December 2018, 616 patients (663 lesions) were enrolled. The mean age was 72.8 ± 9.7 years, 292 (47.4%) patients were female and 523 (84.9%) completed one-year follow-up. Drug-eluting stents were deployed in 606 (91.4%) lesions. The RA success rate - defined as when the operator successfully passed the burr across the target lesion - was 99.4% and the angiographic success rate was 94.8%. 130 (21.4%) procedures developed periprocedural complications. The cumulative MACCE rate at 30-days was 1.5% and at 1-year was 6.3%. The in-hospital mortality rate was 1.1% and the cardiac death rate was 1.6%. Independent risk factors for developing MACCE included the use of an intra-aortic balloon pump (hazard ratio [HR] 3.96, 95% confidence interval [CI] 1.54-10.21; P = 0.004), a history coronary artery bypass graft (HR 2.30, 95% CI 1.01-5.25; P = 0.048), and increased serum creatinine (HR 1.16, 95% CI 1.04-1.30; P = 0.008).

Conclusions

RA is an effective revascularization technique for heavily calcified lesions. This study demonstrates a high success rate and good short- to intermediate-term results of RA-assisted PCI in middle-income countries which are similar to high-income countries. Nevertheless, the rate of periprocedural complications remains high.

Association between coronary artery calcium score and in-stent restenosis after drug-eluting stent implantation

BACKGROUND

Coronary artery calcium (CAC) is a modifiable contributor of in-stent restenosis (ISR), but quantitative analyses using a noninvasive approach are limited. We aimed to investigate the associations between CAC score derived from ECG-gated coronary computed tomography angiography (CCTA) or non-gated non-contrast chest computed tomography (NCCT) and ISR.

METHODS

We included 368 lesions in 194 patients with coronary drug-eluting stent implantations in final analyses. CAC was quantified using the Agatston score. Primary endpoint was ISR, defined as lumen diameter stenosis over 50% at the stent segment or its proximal or distal edges (5-mm segments adjacent to the stent), at angiographic follow-up.

RESULTS

The CAC scores in either CCTA/2.5 mm group (r = 0.7702; P < 0.0001) or NCCT/5 mm group (r = 0.7105; P < 0.0001) were both correlated with in-stent diameter stenosis. The receiver-operating characteristic curve analysis identified a CAC score >245 in CCTA/2.5 mm group as the optimal ISR cutoff (sensitivity, 60.0%; specificity, 83.7%; area under the curve, 0.744; P < 0.001), and >209 in NCCT/5 mm group (sensitivity, 46.7%; specificity, 91.9%; area under the curve, 0.704; P < 0.001). Multivariable logistic regression models indicated a CAC score >245 in CCTA/2.5 mm group and >209 in NCCT/5 mm group independently associated with an 8.46- and 21.89-fold increase in ISR, respectively (all P < 0.01).

CONCLUSIONS

Either a CAC score >245 in CCTA/2.5 mm or >209 in NCCT/5 mm was significantly associated with increased risk in ISR.

Automatic detection of vessel structure by deep learning using intravascular ultrasound images of the coronary arteries

Intravascular ultrasound (IVUS) is a diagnostic modality used during percutaneous coronary intervention. However, specialist skills are required to interpret IVUS images. To address this issue, we developed a new artificial intelligence (AI) program that categorizes vessel components, including calcification and stents, seen in IVUS images of complex lesions. When developing our AI using U-Net, IVUS images were taken from patients with angina pectoris and were manually segmented into the following categories: lumen area, medial plus plaque area, calcification, and stent. To evaluate our AI's performance, we calculated the classification accuracy of vessel components in IVUS images of vessels with clinically significantly narrowed lumina (< 4 mm2) and those with severe calcification. Additionally, we assessed the correlation between lumen areas in manually-labeled ground truth images and those in AI-predicted images, the mean intersection over union (IoU) of a test set, and the recall score for detecting stent struts in each IVUS image in which a stent was present in the test set. Among 3738 labeled images, 323 were randomly selected for use as a test set. The remaining 3415 images were used for training. The classification accuracies for vessels with significantly narrowed lumina and those with severe calcification were 0.97 and 0.98, respectively. Additionally, there was a significant correlation in the lumen area between the ground truth images and the predicted images (ρ = 0.97, R2 = 0.97, p < 0.001). However, the mean IoU of the test set was 0.66 and the recall score for detecting stent struts was 0.64. Our AI program accurately classified vessels requiring treatment and vessel components, except for stents in IVUS images of complex lesions. AI may be a powerful tool for assisting in the interpretation of IVUS imaging and could promote the popularization of IVUS-guided percutaneous coronary intervention in a clinical setting.

Risk Factors for Residual Stenosis After Carotid Artery Stenting

Background and purpose: Stent residual stenosis is an independent risk factor for restenosis after stenting. This study aimed to analyze the factors influencing residual stenosis after carotid artery stenting (CAS). Methods: A total of 570 patients who underwent CAS with 159 closed-loop stents (CLS) and 411 open-loop stents (OLS) from January 2013 to January 2016 were retrospectively enrolled in this study. Carotid stenosis location in the common carotid artery or in internal carotid artery, plaque size, and features (regular or irregular morphology; with or without calcification), degree of carotid artery stenosis, and stent expansion rate were detected by carotid duplex ultrasonography. Residual stenosis was defined as a stenosis rate ≥30% after CAS, as detected by digital subtraction angiography. A logistic regression analysis was used to analyze residual stenosis risk factors. Results: The overall incidence of residual stenosis was 22.8% (130/570 stents). The incidence of residual stenosis in the CLS group was higher than that in the OLS group (29.5 vs. 20.2%, χ² = 5.71, P = 0.017). The logistic regression analysis showed that CLS [odds ratio (OR), 1.933; 95% confidence interval (CI), 1.009-3.702], irregular plaques (OR, 4.237; 95% CI, 2.391-7.742), and plaques with calcification (OR, 2.370; 95% CI, 1.337-4.199) were independent risk factors for residual stenosis after CAS. In addition, a high radial expansion rate of stent was a protective factor for residual stenosis (OR, 0.171; 95% CI, 0.123-0.238). The stenosis location and stent length did not impact the occurrence of residual stenosis. After 1-year follow-up, the incidence of restenosis in the residual stenosis group was higher than that in the group without residual stenosis (13.1 vs. 2.0%, χ² = 28.05, P < 0.001). Conclusions: The findings of this study suggest that plaque morphology, echo characteristics (with calcification), and stents type influence residual stenosis.

Segmentation of Coronary Calcified Plaque in Intravascular OCT Images Using a Two-Step Deep Learning Approach

We developed a fully automated, two-step deep learning approach for characterizing coronary calcified plaque in intravascular optical coherence tomography (IVOCT) images. First, major calcification lesions were detected from an entire pullback using a 3D convolutional neural network (CNN). Second, a SegNet deep learning model with the Tversky loss function was used to segment calcified plaques in the major calcification lesions. The fully connected conditional random field and the frame interpolation of the missing calcification frames were used to reduce classification errors. We trained/tested the networks on a large dataset comprising 8,231 clinical images from 68 patients with 68 vessels and 4,320 ex vivo cadaveric images from 4 hearts with 4 vessels. The 3D CNN model detected major calcifications with high sensitivity (97.7%), specificity (87.7%), and F1 score (0.922). Compared to the standard one-step approach, our two-step deep learning approach significantly improved sensitivity (from 77.5% to 86.2%), precision (from 73.5% to 75.8%), and F1 score (from 0.749 to 0.781). We investigated segmentation performance for varying numbers of training samples; at least 3,900 images were required to obtain stable segmentation results. We also found very small differences in calcification attributes (e.g., angle, thickness, and depth) and identical calcium scores on repetitive pullbacks, indicating excellent reproducibility. Applied to new clinical pullbacks, our method has implications for real-time treatment planning and imaging research.

The role of intravascular ultrasound in percutaneous coronary intervention of complex coronary lesions

Intravascular ultrasound (IVUS) is a catheter-based coronary imaging technique. It utilises the emission & subsequent detection of reflected high frequency (30-60 MHz) sound waves to create high resolution, cross-sectional images of the coronary artery. IVUS has been the cornerstone of intracoronary imaging for more than two decades. When compared to the invasive coronary angiogram which studies only the silhouette of the contrast-filled artery lumen, IVUS also crucially images the vessel wall. Because of this capability, IVUS has greatly facilitated understanding of the coronary atherosclerosis process. Such insights from IVUS reveal how commonly and extensively plain angiography underestimates the true extent of coronary plaque, the characteristics of plaques prone to rupture and cause acute coronary syndromes (lipid rich, thin cap atheroma), and a realisation of the widespread occurrence of vessel remodelling in response to atherosclerosis. Similarly, IVUS has historically provided salutary mechanistic insights that have guided many of the incremental advances in the techniques of percutaneous coronary intervention (PCI). Examples include mechanisms of in-stent restenosis, and the importance of high-pressure post-dilatation of stents to ensure adequate stent apposition and thereby reduce the occurrence of stent thrombosis. IVUS also greatly facilitates the choice of correct diameter and length of stent to implant. Overall, a compelling body of evidence indicates that use of intravascular ultrasound in PCI helps to achieve optimal technical results and to mitigate the risk of adverse cardiac events. In this review, the role of intravascular ultrasound as an adjunct to PCI in complex coronary lesions is explored. The complex coronary situations discussed are the left main stem, ostial stenoses, bifurcation stenoses, thrombotic lesions, the chronically occluded coronary artery, and calcified coronary artery disease. By thorough review of the available evidence, we establish that the advantages of IVUS guidance are particularly evident in each of these complex CAD subsets. In particular, some consider the use of IVUS to be almost mandatory in left main PCI. A comparison with other intracoronary imaging techniques is also explored.

Stent thrombosis in acute coronary syndromes: Patient-related factors and operator-related factors

OBJECTIVE

Stent thrombosis (ST) is a common phenomenon in acute coronary syndromes (ACS) when compared to stable coronary artery disease. This study analyzed the patient- and operator-related risk factors of ST in ACS.

METHODS

Coronary angiograms of 1738 consecutive ACS patients admitted in a large tertiary center between year 2014 and 2016 were analyzed retrospectively for the presence of ST. The paired angiograms [ST in ACS during and after percutaneous coronary intervention (PCI)] of the patients were analyzed by two independent observers, with focus on lesion characteristics and procedure techniques. Clinical and laboratory data were collected.

RESULTS

Stent thrombosis was found in 29 (1.6%) ACS patients, with a combination of at least one clinical/laboratory risk factor and one lesion/operator risk factor identified in 28 (96%) out of the 29 ACS patients with ST. The following risk factors for ST were found: Renal insufficiency (OR=4.14, p<0.001, 95% CI=1.73-9.88), type 2 diabetes (OR=2.21, p=0.034, 95% CI=1.06-4.61), excessive alcohol consumption (OR=3.12, p=0.023, 95% CI=1.17-8.33), stent implantation for ST-elevation myocardial infarction (STEMI) (OR=2.28, p=0.029, 95% CI=1.08-4.81), left main (LM) or left anterior descending artery (LAD) as culprit lesion (OR=2.80, p=0.010, CI 95%=1.27-5.95), and absence of antiplatelet therapy prior to ST (OR=3.58, p=0.002, 95% CI=1.60-7.96). The following lesion/operator possible risk factors were identified: Bifurcation lesion (n=7; 24%), heavy coronary calcifications (n=13; 44%), in-stent restenosis with secondary plate rupture (n=6, 20%), inappropriate stent size selection (n=6, 20%), and errors in periprocedural drug administration (n=4, 14%).

CONCLUSION

ST occurred in 1/62 ACS patients after PCI. A combination of clinical/laboratory and lesion/operator risk factors were present in almost all ACS patients with ST. This finding may support the search for strictly individualized strategies for the treatment of ACS patients with ST after PCI.

Additional debulking efficacy of low-speed rotational atherectomy after high-speed rotational atherectomy for calcified coronary lesion

We aimed to evaluate the additional debulking efficacy of low-speed rotational atherectomy (RA) after high-speed RA by using intravascular imaging. A total of 22 severe calcified coronary lesions in 19 patients (age, 74 ± 10 years; 74% male) were retrospectively analyzed. All of these lesions underwent RA under optical coherence tomography (OCT) or optical frequency domain imaging (OFDI) guidance. At first, we performed high-speed RA with 220,000 rpm until the reduction of rotational speed disappeared; then, low-speed RA with 120,000 rpm using the same burr size was performed. OCT or OFDI was performed after both high-speed and low-speed RAs, and the minimum lumen area were compared. The initial and final burr sizes of high-speed RA were 1.5 (1.5-1.75) and 1.75 (1.5-2.0) mm, respectively. The number of sessions, total duration time, and maximum decreased rotational speed during high-speed RA were 11 ± 5 times, 113 ± 47 s, and 4000 (3000-5000) rpm, respectively. During low-speed RA, the number of sessions, total duration time, and maximum reduction of rotational speed were 3 ± 1 times, 32 ± 11 s, and 1000 (0-2000) rpm, respectively. The minimum lumen area was similar between after high-speed and after low-speed RA [2.61 ± 1.03 mm² (after high-speed RA) vs. 2.65 ± 1.00 mm² (after low-speed RA); P = 0.91]. Additional low-speed RA immediately after sufficient debulking by high-speed RA was not associated with increased lumen enlargement. There was no clinical efficacy of low-speed RA after high-speed RA.

Automated classification of dense calcium tissues in gray-scale intravascular ultrasound images using a deep belief network

Background

IVUS is widely used to quantitatively assess coronary artery disease. The purpose of this study was to automatically characterize dense calcium (DC) tissue in the gray scale intravascular ultrasound (IVUS) images using the image textural features.

Methods

A total of 316 Gy-scale IVUS and corresponding virtual histology images from 26 patients with acute coronary syndrome who underwent IVUS along with X-ray angiography between October 2009 to September 2014 were retrospectively acquired and analyzed. One expert performed all procedures and assessed their IVUS scans. After image acquisition, the DC candidate and corresponding acoustic shadow regions were automatically determined. Then, nine image-base feature groups were extracted from the DC candidates. In order to reduce the dimensionalities, principal component analysis (PCA) was performed, and selected feature sets were utilized as an input for a deep belief network. Classification results were validated using 10-fold cross validation.

Results

The dimensionality of the feature map was efficiently reduced by 50% (from 66 to 33) without any performance decrease using PCA method. Sensitivity, specificity, and accuracy of the proposed method were 92.8 ± 0.1%, 85.1 ± 0.1%, and 88.4 ± 0.1%, respectively (p < 0.05). We found that the window size could largely influence the characterization results, and selected the 5 × 5 size as the best condition. We also validated the performance superiority of the proposed method with traditional classification methods.

Conclusions

These experimental results suggest that the proposed method has significant clinical applicability for IVUS-based cardiovascular diagnosis.

Lesion Preparation with Orbital Atherectomy

Despite significant improvements in stent design, severe coronary calcification continues to impede adequate stent expansion and is associated with worse clinical outcomes. Angiography is limited in its ability to detect and comprehensively characterise calcified plaque. Intravascular imaging provides information on lesion morphology guiding appropriate treatment strategies. Orbital atherectomy allows for lesion preparation of severely calcified plaque prior to stent implantation. Utilising a unique mechanism of action incorporating centrifugal forces, a standard 1.25 mm eccentrically mounted and diamond-coated burr orbits bi-directionally to ablate calcified plaque. Lesion preparation with orbital atherectomy allows for modification of calcified plaque to facilitate stent expansion.

Association between debulking area of rotational atherectomy and platform revolution speed-Frequency domain optical coherence tomography analysis

OBJECTIVES

In this study, we sought to investigate the association between revolution speed of rotational atherectomy (RA) and debulking area assessed by frequency domain-optical coherence tomography (FD-OCT).

BACKGROUND

The number of patients with severe calcified coronary artery disease requiring treatment with calcium ablation, such as RA, is increasing. However, there is little evidence available regarding the association between debulking area and revolution speed during RA.

METHODS

We retrospectively investigated 30 consecutive severely calcified coronary lesions in 29 patients who underwent RA under FD-OCT guidance. The association between preset revolution speed of RA and burr size-corrected debulking area of the calcified lesion was evaluated using a multivariable regression model with nonlinear restricted-cubic-spline, which can help assess nonlinear associations between variables.

RESULTS

The median age of study participants was 73 years (quartile 65-78); 82.8% were male. The median burr size was 1.5 mm (1.5-1.75); median total duration of ablation was 120 s (100-180). FD-OCT revealed that the post-procedural minimum lumen area increased significantly from 1.64 mm² (1.40-2.09) to 2.45 mm² (2.11-2.98) (p < .001). In addition, the burr size-corrected debulking area increased significantly as the preset revolution speed decreased (p = .018), especially when the revolution speed was less than 150,000 rpm. This result implies that additional lumen gain will be obtained by decreasing rpm when the burr speed is set at <150,000 rpm.

CONCLUSIONS

FD-OCT demonstrated that RA with lower revolution speed, below 150,000 rpm, has the potential to achieve greater calcium debulking effect in patients with severe calcified coronary lesions.

In-Hospital and 1-Year Outcomes of Rotational Atherectomy and Stent Implantation in Patients With Severely Calcified Unprotected Left Main Narrowings (from the Multicenter ROTATE Registry)

Heavily calcified unprotected left main (ULM) disease continues to be a challenging situation and represent a high-risk subset for interventional cardiologist. To date, there are limited data investigating the results after rotational atherectomy (RA) in this setting. The aim of this study was to investigate the in-hospital and 1-year outcomes after RA of heavily calcified ULM lesions. A retrospective cohort analysis was performed on all calcified patients with ULM (n = 86) enrolled in the multicenter international ROTATE registry (overall patients, n = 962). End points of the study were the in-hospital and 1-year incidence of major adverse cardiovascular events (MACE): a composite of death, myocardial infarction, and target-vessel revascularization in the ULM versus non-ULM group. Patients in the ULM group were older (p = 0.01) and more frequently with diabetes (p = 0.001) compared with the non-ULM group, whereas intravascular ultrasound guidance was higher, even if not systematic, in the ULM group (p <0.001). No difference was reported between ULM versus non-ULM groups in terms of in-hospital MACE (5.8% vs 8%). At 1 year, MACE rate was higher in ULM versus non-ULM (26.4% vs 14.9%, p = 0.002) mostly driven by target-vessel revascularization (20.3% vs 12.7%, p = 0.05). Even definite/probable stent thrombosis rate was higher in the ULM group (3.9% vs 0.8%). All these events were subacute and 2/3 (75%) were fatal. In conclusion, our multicenter experience shows that RA followed by stent implantation in patients with heavily calcified ULM narrowing is feasible and associated with good in-hospital results. Patient (age and diabetes) and procedural aspects (relatively low intravascular ultrasound guidance) may affect the worse subacute mid-term prognosis in the more complex ULM group.

Real-World Multicenter Registry of Patients with Severe Coronary Artery Calcification Undergoing Orbital Atherectomy

Objectives

We evaluated the safety and efficacy of orbital atherectomy in real‐world patients with severe coronary artery calcification (CAC).

Background

The presence of severe CAC increases the complexity of percutaneous coronary intervention as it may impede stent delivery and optimal stent expansion. Atherectomy may be an indispensable tool for uncrossable or undilatable lesions by modifying severe CAC. Although the ORBIT I and II trials report that orbital atherectomy was safe and effective for the treatment of severe CAC, patients with kidney disease, recent myocardial infarction, long diffuse disease, severe left ventricular dysfunction, and unprotected left main disease were excluded.

Methods

This retrospective study included 458 consecutive patients with severe CAC who underwent orbital atherectomy followed by stenting from October 2013 to December 2015 at 3 centers.

Results

The primary endpoint of major adverse cardiac and cerebrovascular events at 30 days was 1.7%. Low rates of 30‐day all‐cause mortality (1.3%), myocardial infarction (1.1%), target vessel revascularization (0%), stroke (0.2%), and stent thrombosis (0.9%) were observed. Angiographic complications were low: perforation was 0.7%, dissection 0.9%, and no‐reflow 0.7%. Emergency coronary artery bypass graft surgery was performed in 0.2% of patients.

Conclusion

In the largest real‐world study of patients who underwent orbital atherectomy, including high‐risk patients who were not surgical candidates as well as those with very complex coronary anatomy, acute and short‐term adverse clinical event rates were low. A randomized clinical trial is needed to identify the ideal treatment strategy for patients with severe CAC.

Classification of calcium in intravascular OCT images for the purpose of intervention planning

The presence of extensive calcification is a primary concern when planning and implementing a vascular percutaneous intervention such as stenting. If the balloon does not expand, the interventionalist must blindly apply high balloon pressure, use an atherectomy device, or abort the procedure. As part of a project to determine the ability of Intravascular Optical Coherence Tomography (IVOCT) to aid intervention planning, we developed a method for automatic classification of calcium in coronary IVOCT images. We developed an approach where plaque texture is modeled by the joint probability distribution of a bank of filter responses where the filter bank was chosen to reflect the qualitative characteristics of the calcium. This distribution is represented by the frequency histogram of filter response cluster centers. The trained algorithm was evaluated on independent ex-vivo image data accurately labeled using registered 3D microscopic cryo-image data which was used as ground truth. In this study, regions for extraction of sub-images (SI's) were selected by experts to include calcium, fibrous, or lipid tissues. We manually optimized algorithm parameters such as choice of filter bank, size of the dictionary, etc. Splitting samples into training and testing data, we achieved 5-fold cross validation calcium classification with F1 score of 93.7±2.7% with recall of ≥89% and a precision of ≥97% in this scenario with admittedly selective data. The automated algorithm performed in close-to-real-time (2.6 seconds per frame) suggesting possible on-line use. This promising preliminary study indicates that computational IVOCT might automatically identify calcium in IVOCT coronary artery images.

Intravascular imaging of coronary calcification and its clinical implications

Calcium impacts the natural history and treatment of coronary artery disease in many ways. Intravascular imaging studies, mostly intravascular ultrasound, but more recently studies using optical coherence tomography, have been instrumental in increasing our understanding of the relationship between calcium and coronary atherosclerosis, the predictors, the natural history of this relationship, and the impact on treatment. On one hand, stable coronary lesions are associated with more calcium than unstable lesions; and the amount of calcium may affect the success of percutaneous coronary intervention. On the other hand, calcium correlates with plaque burden; unstable lesions are associated with focal calcium deposits; and calcific nodules are one of the morphologies of vulnerable plaque. This review focuses on more than 20 years of intravascular imaging studies of the relationship between calcium and coronary atherosclerosis.

Plaque morphology (the PLAC Scale) on CT angiography: predicting long-term anatomical success of primary carotid stenting

OBJECT

Carotid angioplasty and stenting has emerged as an alternative to carotid endarterectomy for the treatment of atherosclerotic carotid stenosis. Primary carotid stenting, performed using self-expanding stents alone without deliberate use of embolic protection devices and balloon angioplasty, has been shown to be effective and faster, cheaper, and potentially safer than conventional techniques. However, the long-term morphological results of this technique have not been established. The aim of this study was to determine whether preprocedural carotid plaque imaging at the site of maximal stenosis by using CT angiography (CTA) could predict the long-term morphological outcome of primary carotid stenting.

METHODS

One hundred eighty-one patients were treated over an 11-year period. Preprocedural CTA was performed in 102 of these. A morphological scale (the Predicting Long-term outcome with Angioplasty of the Carotid artery [PLAC] Scale), with grades from 0 to 4 and A or B, was used to evaluate the circumferential degree of plaque calcification, and the presence or absence of soft plaque. All patients were followed using duplex carotid ultrasound and plain radiographs. Satisfactory morphological outcome was defined as a peak systolic velocity < 120 cm/s and internal carotid artery/common carotid artery ratio < 1.4.

RESULTS

The average follow-up duration was 29.7 months (median 24.5 months, range 0.3–87 months). Univariate logistic regression demonstrated that a low calcification grade (p < 0.001), less thick calcification (p < 0.001), and moderate amounts of soft plaque (p < 0.001) are factors that are highly associated with good long-term outcome. Multivariate analyses confirmed that these factors are independent of each other in predicting outcome.

CONCLUSIONS

The long-term morphological outcome of primary carotid stenting was predicted with considerable accuracy by using a straightforward CTA carotid plaque grading scale.

Rotational Atherectomy and Stent Implantation for Calcified Left Main Lesions

Background

Left main coronary artery (LMCA) bifurcation and heavily calcified lesions are common and challenging to treat percutaneously. Rotational atherectomy (RA) may be beneficial in this setting to facilitate stent placement though direct supporting evidence is lacking. This study sought to analyze patients who underwent RA of the LMCA.

Methods

Consecutive cases involving RA of the LMCA between 1/1/2004 and 12/31/2009 at a private, tertiary referral hospital were reviewed retrospectively. Medical records, angiograms and clinically driven follow-up were reviewed.

Results

Thirty-one cases were identified (20 protected, 11 unprotected), including 23 with stent implantation (21 drug-eluting, 2 bare metal). All 31 lesions had moderate to severe calcification, 84% involved the distal segment. Mean burr-to-vessel ratio was 0.43. Overall angiographic success was 90% (28/31) and was higher with a drug-eluting stent versus no stent (100% vs. 62%; P = 0.0153). In-hospital major adverse cardiovascular events (MACE) occurred in 1 patient (3%). Mid-term MACE occurred in 6 patients (26%) and tended to occur less frequently in patients with protected LMCAs (P = 0.0697). At final follow-up, patients were more likely to be alive and free from angina with a protected LMCA (94% vs. 57% unprotected; P = 0.0564) and with a drug-eluting stent (89% vs. 50% with no stent; P = 0.0281).

Conclusions

RA of the LMCA to facilitate stent implantation appears to be safe and effective with favorable mid-term outcomes. In the setting of severe calcification and distal LMCA involvement RA and drug-eluting stent implantation should be considered.

Treatment of calcified ostial disease by rotational atherectomy and adjunctive cutting balloon angioplasty prior to stent implantation

Both heavily calcified and ostial lesions are difficult to deal with by percutaneous transluminal coronary angioplasty (PTCA) alone. Acute results are often sub-optimal, complications are more frequent, and long-term results are disappointing. Optimal stent deployment may not be possible unless satisfactory lesion dilatation is achieved and the lesion made more compliant. The use of rotational atherectomy and cutting balloon angioplasty to a calcified ostial lesion in the left circumflex coronary artery prior to stent implantation is reported.

An evidence-based approach to the use of rotational and directional coronary atherectomy in the era of drug-eluting stents: when does it make sense?

Advances in percutaneous interventions have profoundly changed the way we manage patients with coronary and peripheral arterial disease. Though the use of stents, particularly drug-eluting stents, is the preferred method for revascularization because of ease of use and lower restenosis rates, there are many short comings. Ostial and bifurcation lesions as well as heavily calcified and tortuous arteries remain problematic. Mechanical debulking with rotational and direct coronary atherectomy may be beneficial in these situations. In this review, we present the general concepts of mechanical debulking and attempt to summarize the available data on its use in the setting of drug-eluting stents. In addition, we will discuss its special role in the management of peripheral arterial disease.

Balloon folding affects the symmetry of stent deployment: experimental and computational evidence

The level of restenosis following coronary artery stenting may be related to the deployed stent geometry. This study investigated the influence of two balloon folding patterns (;C' and ;S' shaped) on stent deployment. In vitro stent expansion showed ;S' shape folding produced more uniform expansion than ;C' shape folding. A numerical contact model (NCM) was developed to study the detail of load transfer between balloon and stent. Finite element analysis of the Palmaz-Schatz 204C stent provided a composite non-linear material model for the NCM. Agreement between the predicted final stent geometry and experimental results was strongly dependent on the frictional coefficient between the stent and balloon. We conclude that non-uniform contact may contribute to the asymmetry of deployed stents reported clinically.

Rescuing an entrapped guidewire using a Tornus catheter

Entrapment of a guidewire is a rare event, but it could happen especially in severe calcified stenotic lesion. This complication is life-threatening because it can lead to myocardial ischemia, infarction, or lethal arrhythmia due to intracoronary thrombosis. In the event of failed retrieval and persistent signs of ischemia, patients should be urgently referred to surgery. During percutaneous coronary intervention, the Tornus catheter has been applied to patients with severe coronary artery disease when balloon catheter or microcatheter cannot be crossed across the lesion after successful wire crossing. This is a case of a patient that a Tornus catheter rescued an entrapped guidewire in severe calcified coronary disease.

Coronary perforation during percutaneous coronary intervention

Coronary perforation is an undesirable complication during percutaneous coronary intervention (PCI). We reviewed the cases of overt coronary perforation in our institute and analyzed their clinical backgrounds, the characteristics of the target lesion, management, and clinical outcomes. Between 1991 and 2005, we experienced 12 cases (0.35%) of coronary perforation in a total of 3415 PCI procedures. The perforation occurred during the use of debulking devices in 3 cases, immediately after stenting in 2, immediately after postdilatation of the stent in 2, and during wiring in 3 cases. Restoration was attempted by long inflation of a balloon in 7 cases, implantation of a covered stent graft in 1, and emergency surgical repair in 1 case. Subsequent cardiac tamponade occurred in 3 patients who required pericardiocentesis, and 1 patient died due to congestive heart failure. Administration of protamine was effective in stopping the bleeding in 6 patients, whereas continuation of antiplatelet therapy resulted in no overt rebleeding. Coronary perforation during PCI is a rare complication but is associated with significant morbidity and mortality. Intravenous administration of protamine is effective when it is used in conjunction with nonsurgical devices for initial management of perforation.

Initial and Long-Term Outcomes of Sirolimus-Eluting Stents for Calcified Lesions Compared With Bare-Metal Stents

The aim of this study was to compare the initial and long-term outcomes of sirolimus-eluting stents (SES) and bare-metal stents (BMS) in patients with calcified lesions without performing rotational atherectomy. The subjects were 79 consecutive lesions (38 in the SES group and 41 in the BMS group) which were confirmed to have superficially calcified lesions by intravascular ultrasound. In all lesions, the stent was implanted after predilatation with a balloon. The patient characteristics were not different between the 2 groups. All procedures were successfully performed in both groups. Vessel area was significantly smaller in the SES group than in the BMS group (11.01 +/- 3.88 mm(2) versus 13.08 +/- 3.49 mm(2), P < 0.005), as was the lumen area (5.41 +/- 2.31mm(2) versus 6.48 +/- 2.04 mm(2), P < 0.005). Minimum stent area was significantly smaller in the SES group than in the BMS group (5.61 +/- 1.54 mm(2) versus 6.69 +/- 1.74 mm(2), P < 0.01). In cases in whom angiographic follow-ups were performed, the late loss was significantly smaller in the SES group than in the BMS group (0.19 +/- 0.49 mm versus 0.76 +/- 0.48 mm, P < 0.001). The restenosis rate was significantly lower in the SES group than in the BMS group (8.8% versus 33.3%, P < 0.05) and the TLR rate tended to be lower in the SES group (7.9% versus 19.5%). Stent thrombosis was not observed in either group. The results suggest that SES are more effective than BMS and can be used safely when treating calcified lesions if predilatation with a balloon is possible.

Management of calcified lesions in 2004

Calcified lesions are encountered with increasing frequency in the catheterization laboratory. Percutaneous coronary interventions of calcified lesions are associated with a higher complication rate than percutaneous intervention on non-calcified lesions. The review focuses on current management strategies in the drug eluting stent era of this complex lesion subset. Evidence based approaches to treat calcified coronary lesions with balloon based and atherectomy devices as adjunctive modalities in the drug eluting stent era are discussed in this article.

First clinical experience of a novel penetration catheter for patients with severe coronary artery stenosis

The study aimed to evaluate the efficacy of a novel penetration catheter for severe coronary artery disease. Severe coronary artery diseases such as chronic total occlusions or severe calcified stenoses sometimes obstruct the subsequent crossing of balloon catheter after successful wire crossing. A novel penetration over-the-wire catheter has been developed for severe coronary artery disease. The main shaft is a coreless stainless coil that consists of eight stranded stainless wires to cross through a severe stenosis by manual rotation. This device was applied during percutaneous coronary intervention for patients with severe coronary artery disease obstructing the subsequent crossing of balloon or microcatheters after successful wire crossing. Initial results were examined. Fourteen eligible patients were enrolled consecutively. Among those, 10 patients had chronic total occlusion and 7 patients showed severe angiographical calcification. The device was successfully crossed through the lesion and enabled subsequent dilatation in all patients without any complication. This new device enables the crossing of severe coronary artery stenoses and therefore favors further dilatation in this lesion subset.

Excimer laser facilitated percutaneous coronary intervention of a nondilatable coronary stent

A patient is described in which excimer laser percutaneous coronary intervention is performed inside a suboptimally expanded stent due to nondilatable calcified plaque. The use of excimer laser facilitated full expansion of the stent with a balloon.

Stent deployment in calcified lesions: can we overcome calcific restraint with high-pressure balloon inflations?

Although significant coronary artery (CA) calcification is believed to affect stent deployment, the exact impact on stent deployment after high-pressure balloon inflations is unknown. Intracoronary intravascular examination (ICUS) was performed in 27 moderate-severe calcified CA lesions before and after stent implantation. In case of unsatisfactory results (in-stent area < 90%, minimal in-stent diameter/maximal in-stent diameter < 0.8), further inflations up to 20 atm guided by ICUS were applied. Initially, stent expansion was adequate in 10 stents (37%) and symmetric in 19 (70%). After inflation at 20 atm, stents with adequate expansion increased to 16 (59%, P = 0.0036), but stents with symmetry decreased to 13 (48%, P = 0.0045). Stent expansion was inversely correlated to the arc of calcium (r = -0.8, P < 0.0001). There were five patients with clinical restenosis at 6 months (18%). Increases in stent lumen area with high-pressure balloon inflations in moderate-severe calcified CA lesions are at the expense of symmetry. This may affect clinical restenosis.

Comparison of texture analysis methods for the characterization of coronary plaques in intravascular ultrasound images

Intravascular Ultrasound (IVUS) is a diagnostic imaging technique that provides tomographic visualization of coronary arteries. The aim of this study was to evaluate five texture analysis techniques and determine their ability to distinguish between plaque lesions of different composition. Using histological correlation, regions of calcified, fibrous, and necrotic core plaque were chosen from 27 coronary plaques. First-order statistics, Haralick's method, Laws' texture energy method, the neighborhood gray-tone difference matrix method, and texture spectrum features were examined using discriminant analysis. Self-validation indicated that Haralick's method yielded the most accurate results, with resubstitution and cross-validation error rates of 0.00 and 14.76%, respectively. Further optimization gave error rates of 6.67%, using only two discriminating features, IDM and entropy.

Reproducibility of neointima quantification with motorized intravascular ultrasound pullback in stented coronary arteries

BACKGROUND

Intravascular ultrasound (IVUS) imaging has shown excellent reproducibility immediately after coronary stent implantation. However, the variability of measurements in lesions late after stent implantation, when neointima formation is present, has not been studied. Neointimal tissue is generally low echogenic and thus difficult to quantify. We therefore sought to analyze the reproducibility of morphometric measurements late after stent implantation.

METHODS AND RESULTS

Fifty consecutive patients were investigated 6 months after Palmaz-Schatz stent implantation (motorized catheter pullback 0.5 mm/s). Two experienced investigators independently identified the stent area, lumen area, and neointimal area at different sites within the stent. Planimetric measurements were performed with commercially available software. Correlation coefficient and mean difference for corresponding measurements were calculated for the intraobserver and interobserver comparisons. Variability for the intraobserver and interobserver comparisons was similar. Observer agreement regarding the presence of neointimal hyperplasia was as high as 71% (interobserver comparison 62%). The mean difference for neointima area was 0.06 +/- 1.5 mm(2) (-0.6 +/- 1.5 mm(2)); mean differences for lumen area were 0.02 +/- 0.19 mm(2) (0.03 +/- 0.17 mm(2)) and for stent area 0.01 +/- 0.09 mm(2) (-0.02 +/- 0.12 mm(2)) (values for interobserver comparison are given in parentheses). Correlation between measurements was high for all structures: correlation coefficients were 0.66 (0.69) for neointima, 0.94 (0.95) for lumen, and 0.95 (0. 91) for stent area.

CONCLUSIONS

Morphometric measurements of IVUS investigations with motorized IVUS pullback late after stent placement show good reproducibility. Intraobserver variability and interobserver variability are low. Differences for corresponding measurements were more pronounced for neointima area. Motorized catheter pullback guarantees high reliability of IVUS measurements and should be used routinely for clinical IVUS studies.