Prediction of carotid artery in-stent restenosis by quantitative assessment of vulnerable plaque using computed tomography

Surveillance and risk factors for early restenosis following transcarotid artery revascularization

OBJECTIVE

Restenosis after transcarotid artery revascularization (TCAR) is a known complication. When identified in the early postoperative period, it may be related to technique. We evaluated our TCAR experience to identify potentially modifiable factors impacting restenosis.

METHODS

This is a single-institution, retrospective review of patients undergoing TCAR from November 2017 to July 2022. Restenosis was defined as >50% stenosis on duplex ultrasound (DUS) examination or computed tomographic angiography (CTA). Continuous variables were compared using Kruskal-Wallis's test. Categorical variables were compared using the Fisher's exact test.

RESULTS

Of 61 interventions, 11 (18%) developed restenosis within the median follow-up of 345 days (interquartile range, 103-623 days). Among these patients, 82% (9/11) had >50% stenosis, and 18% (2/11) had >80% stenosis. Both patients with high-grade restenosis were symptomatic and underwent revascularization. Diagnosis of post-TCAR restenosis was via DUS examination in 45% (5/11), CTA in 18% (2/11), or both CTA/DUS examination in 36% (4/11). Restenosis occurred within 1 month in 54% (6/11) and 6 months in 72% (8/11) of patients. However, three of the six patients with restenosis within 1 month had discordant findings on CTA vs DUS imaging. Patient comorbidities, degree of preoperative stenosis, medical management, balloon size, stent size, lesion characteristics, and predilatation angioplasty did not differ. Patients with restenosis were younger (P = .02), had prior ipsilateral endarterectomy (odds ratio [OR], 6.5; P = .02), had history of neck radiation (OR, 18.3; P = .01), and lower rate of postdilatation angioplasty (OR, 0.11; P = .04), without an increased risk of neurological events.

CONCLUSIONS

Although post-TCAR restenosis occurred in 18% of patients, only 3% of patients had critical restenosis and required reintervention. Patient factors associated with restenosis were younger age, prior endarterectomy, and history of neck radiation. Although early restenosis may be mitigated by improved technique, the only technical factor associated with restenosis was less use of postdilatation angioplasty. Balancing neurological risk, this factor may have increased application in appropriate patients. Diagnosis of restenosis was inconsistent between imaging modalities; current surveillance paradigms and diagnostic thresholds may warrant reconsideration.

Relationship between uric acid to albumin ratio and in-stent restenosis in patients with coronary artery disease undergoing drug-eluting stenting

BACKGROUND

In-stent restenosis (ISR) in patients undergoing percutaneous coronary intervention (PCI) to treat coronary artery disease (CAD) is an urgent issue in clinical practice. Recent studies have highlighted uric acid-albumin ratio (UAR) as a new marker for evaluating inflammation and oxidative stress, capable of predicting cardiovascular ailments. We aimed to examine the correlation between UAR levels and ISR in patients who underwent drug-eluting stent (DES) implantation.

METHODS

We included 503 patients with CAD who underwent initial DES implantation and angiography during the follow-up period. Based on coronary angiographic findings, the patients were categorized into ISR (n = 73) and non-ISR groups (n = 430). Before angiography, laboratory parameters were measured for all enrolled patients. To ascertain the influential factors linked to ISR, multivariate logistic regression analysis was performed. The predictive capability of UAR in determining ISR was assessed using receiver operating characteristic (ROC) curve analysis. Statistical significance was set at P  < 0.05.

RESULTS

Multivariate logistic regression analysis revealed that diabetes mellitus, stent length, UAR, albumin levels, and C-reactive protein levels independently predicted ISR. ROC curve analysis revealed that UAR had an area under the curve of 0.767 (95% CI: 0.709 - 0.826) for predicting ISR and demonstrated that UAR outperformed the individual predictive abilities of uric acid and albumin for ISR.

CONCLUSION

UAR was associated with ISR in patients with CAD undergoing PCI with DES implantation. Moreover, ROC curve analysis demonstrated that UAR exhibited superior predictive accuracy for ISR compared with evaluating uric acid and albumin levels separately.

Impact of calcified plaque volume on technical and 3-year outcomes after transcarotid artery revascularization

OBJECTIVE

We sought to quantify the percent calcification within carotid artery plaques and assess its impact on percent residual stenosis and rate of restenosis in patients undergoing transcarotid artery revascularization for symptomatic and asymptomatic carotid artery stenosis.

METHODS

A retrospective review of prospectively collected institutional Vascular Quality Initiative data was performed to identify all patients undergoing transcarotid artery revascularization from December 2015 to June 2021 (n = 210). Patient and lesion characteristics were extracted. Using a semiautomated workflow, preoperative computed tomography head and neck angiograms were analyzed to determine the calcified plaque volume in distal common carotid artery and internal carotid artery plaques. Intraoperative digital subtraction angiograms were reviewed to calculate the percent residual stenosis post-intervention according to North American Symptomatic Carotid Endarterectomy Trial criteria. Peak systolic velocity and end-diastolic velocity were extracted from outpatient carotid duplex ultrasound examinations. Univariate logistic regression was performed to analyze the relationship of calcium volume percent and Vascular Quality Initiative lesion calcification to percent residual stenosis in completion angiograms. Kaplan-Meier analysis examined the relationship between calcium volume percent and in-stent stenosis over 36 months.

RESULTS

One hundred ninety-seven carotid arteries were preliminarily examined. Predilation was performed in 87.4% of cases with a mean balloon diameter of 5.1 ± 0.7 mm and a mean stent diameter was 8.8 ± 1.1 mm. The mean calcium volume percent was 11.9 ± 12.4% and the mean percent residual stenosis was 16.1 ± 15.6%. Univariate logistic regression demonstrated a statistically significant difference between calcium volume percent and percent residual stenosis (odds ratio [OR], 1.324; 95% confidence interval [CI], 1.005-1.746; P = .046). Stratified by quartile, only the top 25% of calcified plaques (>18.7% calcification) demonstrated a statistically significant association with higher percent residual stenosis (OR, 2.532; 95% CI, 1.049-6.115; P =.039). There was no statistical significance with lesion calcification (OR, 1.298; 95% C,: 0.980-1.718; P = .069). A Kaplan-Meier analysis demonstrated a statistically significant increase in the rate of in-stent stenosis during a 36-month follow-up for lesions containing >8.2% calcium volume (P = .0069).

CONCLUSIONS

A calcium volume percent of >18.7% was associated with a higher percent residual stenosis, and a calcium volume percent of >8.2% was associated with higher in-stent stenosis at 36 months. There was one clinically diagnosed stroke during the follow-up period, demonstrating the overall safety of the procedure.

Analysis of the Correlation Between the Ratio of Monocytes to High-Density Lipoprotein Cholesterol and in-Stent Restenosis in Patients with Premature Coronary Heart Disease

BACKGROUND

High-density lipoprotein cholesterol (HDL-C) and monocytes are associated with coronary artery disease, and the ratio of monocytes to high-density lipoprotein (MHR) is associated with long-term adverse outcomes and the recurrence of atrial fibrillation. Currently, the trend of coronary heart disease proned to young people is becoming prominent. However, the relationship between MHR and in-stent restenosis (ISR) in patients with premature coronary heart disease (PCHD) has not been investigated. Therefore, we aimed to assess the relationship between MHR and ISR in patients with PCHD.

METHODS

We retrospectively included 257 patients (men ≤ 55 years old, women ≤ 65 years old) with PCHD who underwent drug-eluting stent implantation and follow-up coronary angiography at the First Affiliated Hospital of Zhengzhou University from September 2016 to September 2019. Patients were divided into ISR and non-ISR groups depending on their follow-up coronary angiography results. Relative clinical information was recorded and analyzed. A receiver operating characteristic curve analysis was used to determine the optimum pre-procedural MHR cutoff value to predict ISR.

RESULTS

Logistic regression analysis showed that MHR, smoking history, and fibrinogen were independent risk factors for ISR in patients with PCHD. The area under the receiver operating characteristic curve (AUC) of MHR was 0.750 (95% confidence interval, 0.695-0.820; P < .001), the cutoff value was 546.88, and the specificity and sensitivity were 65.2% and 78%, while the AUC of monocytes was 0.631 (95% confidence interval, 0.638-0.794; P < .001), the cutoff value was 590, and the specificity and sensitivity were 77.1% and 60.0%.

CONCLUSION

MHR is an independent risk factor for ISR in patients with PCHD and showed a certain predictive value.

Estimated Glomerular Filtration Rate as a Predictor of Restenosis After Carotid Stenting Using First-Generation Stents

This study evaluated the impact of the baseline estimated glomerular filtration rate (eGFR) on clinical and angiographic outcomes and long-term in-stent restenosis (ISR) rates in patients undergoing elective carotid artery stenting (CAS) procedures. Consecutive patients who underwent CAS were retrospectively enrolled (n = 456). At the end of 3 years of follow-up, patients who had died or were lost follow-up were excluded from the study and a final analysis was performed using data from the remaining 405 patients. The study population (n = 405) was divided into 3 tertiles based on the tertile values of the eGFR level (T1, T2, and T3); then, clinical and procedural characteristics and 3-year ISR rates were compared between the groups. An ISR of 50% was detected in 49 (12%) surviving patients. The 3-year ISR was higher among patients with the lowest eGFR values (T1) by 3.7 times (95% CI: 2.01-11.38) than that among patients with the highest eGFR values (T3). These significant relationships persisted following adjustment for confounders. A lower baseline eGFR level was significantly associated with an increased ISR rate. Decreased renal function may be a predictor of ISR after CAS using first-generation stents.

Inflow Hemodynamics of Intracranial Aneurysms: A Comparison of Computational Fluid Dynamics and 4D Flow Magnetic Resonance Imaging

PURPOSE

Although the inflow hemodynamics of cerebral aneurysms are key factors in their rupture and recurrence after endovascular treatments, the most available method for inflow hemodynamics evaluation remains unestablished. We compared the efficacy of inflow hemodynamics evaluation using computational fluid dynamics (CFD) analysis and that using four-dimensional (4D) flow magnetic resonance imaging (MRI).

METHODS

In 23 unruptured cerebral aneurysms, the inflow hemodynamics was evaluated using both CFD and 4D flow MRI. The evaluated parameters included visually classified inflow jet patterns, the inflow rate ratio (the ratio of the inflow rate at the aneurysmal orifice to the flow rate in the proximal parent artery), and the velocity ratio (the ratio of the inflow velocity to the velocity in the proximal parent artery). The Shapiro-Wilk test was used to assess the normality of variable data, and logarithmic transformation was performed for variables with non-normal distributions. Data analysis was performed using Pearson correlation analyses and the chi-square test.

RESULTS

There was a significant correlation between inflow jet patterns evaluated by CFD and 4D flow MRI (p = 0.008). Moreover, there was a strong correlation between the inflow rate ratios evaluated by CFD and 4D flow MRI (r = 0.801; p <0.001). Furthermore, there was a moderate correlation between the velocity ratios measured by CFD and 4D flow MRI (r = 0.559; p = 0.008).

CONCLUSION

Inflow hemodynamics evaluated by CFD analysis and 4D flow MRI showed good correlations in inflow jet pattern, inflow rate ratio, and velocity ratio.

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.

The management of carotid restenosis: a comprehensive review

Carotid artery stenosis (CS) is a major medical problem affecting approximately 10% of the general population 80 years or older and causes stroke in approximately 10% of all ischemic events. In patients with symptomatic, moderate-to-severe CS, carotid endarterectomy (CEA) and carotid angioplasty and stenting (CAS), has been used to lower the risk of stroke. In primary CS, CEA was found to be superior to best medical therapy (BMT) according to 3 large randomized controlled trials (RCT). Following CEA and CAS, restenosis remains an unsolved problem involving a large number of patients as the current treatment recommendations are not as clear as those for primary stenosis. Several studies have evaluated the risk of restenosis, reporting an incidence ranging from 5% to 22% after CEA and an in-stent restenosis (ISR) rate ranging from 2.7% to 33%. Treatment and optimal management of this disease process, however, is a matter of ongoing debate, and, given the dearth of level 1evidence for the management of these conditions, the relevant guidelines lack clarity. Moreover, the incidence rates of stroke and complications in patients with carotid stenosis are derived from studies that did not use contemporary techniques and materials. Rapidly changing guidelines, updated techniques, and materials, and modern medical treatments make actual incidence rates barely comparable to previous ones. For these reasons, RCTs are critical for determining whether these patients should be treated with more aggressive treatments additional to BMT and identifying those patients indicated for surgical or endovascular treatments. This review summarizes the current evidence and controversies concerning the risks, causes, current treatment options, and prognoses in patients with restenosis after CEA or CAS.

Asymptomatic carotid intraplaque hemorrhage is associated with a high risk of cerebral infarction and death after cardiovascular surgery

BACKGROUND

There is a lack of information on the natural history of asymptomatic carotid artery stenosis (AsymCS) associated with cardiovascular diseases that require surgery. The aim of this study was to investigate risk factors for postoperative ipsilateral ischemic stroke and all-cause mortality after cardiovascular surgery in patients with AsymCS.

METHODS

Among 2158 patients who underwent cardiovascular surgery, 150 patients with AsymCS who didn't undergo carotid revascularization were included. The relationships between preoperative factors, including carotid intraplaque hemorrhage (IPH), and postoperative ipsilateral ischemic stroke and all-cause mortality were analyzed retrospectively.

RESULTS

During the median follow-up of 1087 days of 150 patients with 19 IPH, 12 (8.0%) and 21 (14.0%) encountered ipsilateral infarction and all-cause mortality, respectively. Multivariable Cox regression analyses indicated that IPH was significantly predictive of both ipsilateral infarction (hazard ratio [HR] 21.31, 95% confidence interval [CI], 4.98-91.17; P ≤.001) and all-cause mortality (HR 4.64, 95% CI, 1.61-13.34; P = .004). Another significant factor was peak systolic velocity for ipsilateral infarction with the cutoff velocity of 227 cm/s by the receiver-operating characteristic curve.

CONCLUSIONS

In this cohort of patients with AsymCS undergoing cardiovascular surgery, IPH had a close connection with a high risk of both postoperative ischemic stroke and mortality after cardiovascular surgery.

Carotid Geometry as a Predictor of In-Stent Neointimal Hyperplasia - A Computational Fluid Dynamics Study

BACKGROUND

Carotid angioplasty and stenting (CAS) is emerging as an alternative treatment for carotid stenosis, but neointimal hyperplasia (NIH) remains a drawback of this treatment strategy. This study aimed to evaluate the effect of variations of carotid bifurcation geometry on local hemodynamics and NIH.Methods and Results:Hemodynamic and geometric effects on NIH were compared between 2 groups, by performing computational fluid dynamics (CFD) simulations both on synthetic models and patient-specific models. In the idealized models, multiple regression analysis revealed a significant negative relationship between internal carotid artery (ICA) angle and the local hemodynamics. In the patient-derived models, which were reconstructed from digital subtraction angiography (DSA) of 25 patients with bilateral CAS, a low time-average wall shear stress (TAWSS) and a high oscillatory shear index (OSI) were often found at the location of NIH. Larger difference values of the OSI percentage area (10.56±20.798% vs. -5.87±18.259%, P=0.048) and ECA/CCA diameter ratio (5.64±12.751% vs. -3.59±8.697%, P=0.047) were detected in the NIH-asymmetric group than in the NIH-symmetric group.

CONCLUSIONS

Changes in carotid bifurcation geometry can make apparent differences in hemodynamic distribution and lead to bilateral NIH asymmetry. It may therefore be reasonable to consider certain geometric variations as potential local risk factors for NIH.

Contrast-enhanced transoral carotid ultrasonography for the evaluation of plaque protrusion after carotid artery stenting

A 67 year-old man was admitted to our hospital because of mild left hemiparesis and was diagnosed with cerebral infarction caused by right internal carotid artery stenosis. He was treated with dual antiplatelet therapy and scheduled for carotid artery stenting 14 days after onset. The preoperative right carotid angiogram showed 60% stenosis by the NASCET criteria, with an ulcer. The postoperative angiogram suggested protrusion in the stent, which could not be seen on conventional carotid ultrasonography because of its high location. On transoral carotid ultrasonography, clear delineation of the lesion was not possible due to color blurs. Contrast-enhanced transoral carotid ultrasonography (CETOCU) clearly demonstrated the protrusion and delineated the lumen within the stent.

Elevated Levels of Very Low-density Lipoprotein Cholesterol Independently Associated with In-stent Restenosis in Diabetic Patients after Drug-eluting Stent Implantation

Background:

High rate of in-stent restenosis (ISR) remained an unsolved clinical problem in clinical practice, especially among patients with diabetes mellitus (DM). Diabetic patients often had hypertriglyceridemia with elevated levels of very low-density lipoprotein cholesterol (VLDL-C). Increasing evidence suggested that VLDL-C was known as a significant risk factor for atherosclerosis and had been recommended as a treatment target by current dyslipidemia guidelines. However, the role of VLDL-C in the occurrence and development of ISR in coronary artery disease (CAD) patients with DM had not been studied. The aim of this study was to evaluate the association between the elevated levels of VLDL-C and the risk of ISR in CAD patients with DM.

Methods:

A total of 1390 diabetic patients, who underwent coronary drug-eluting stent (DES) implantation at Beijing Anzhen Hospital and followed up by angiography within 6–24 months, were consecutively enrolled. Patients’ demographic and clinical characteristics, including age, gender, CAD risk factors, family history, life style, medical history, and coronary angiographic information, were collected carefully at baseline percutaneous coronary intervention and follow-up angiography. Multivariate Cox's proportional hazards regression modeling using the step-wise method (entry, 0.05; removal, 0.05) was used to determine the independent risk associated with ISR in diabetic patients.

Results:

Finally, 1206 of patients were included in this study. ISR occurred in 132/1206 diabetic patients (10.9%) by follow-up angiography. Patients with ISR had elevated median serum VLDL-C levels compared with those without ISR (0.65 mmol/L vs. 0.52 mmol/L, P = 0.030). The multivariate regression analysis showed that VLDL-C was significantly associated with the risk of ISR in diabetic CAD patients (hazard ratio [HR] = 1.15, 95% confidence interval [CI]: 1.03–1.29, P = 0.017). The HR for the risk of ISR associated with VLDL-C level ≥0.52 mmol/L was 3.01 (95% CI: 1.24–7.34, P = 0.015).

Conclusion:

The elevated level of serum VLDL-C was a significant and independent risk factor for ISR in diabetic CAD patients after coronary DES implantation.

Objective evaluation of cerebrovascular reactivity for acetazolamide predicts cerebral hyperperfusion after carotid artery stenting: Comparison with region of interest methods

BACKGROUND AND PURPOSE

Hemodynamic impairments are considered risk factors of cerebral hyperperfusion after carotid artery stenting (CAS); measurement by Single-photon emission computed tomography (SPECT) using a subjective region of interest (ROI) method lacks consistency and reproducibility.

MATERIALS AND METHODS

The present study compared objective perfusion analysis (stereotactic extraction estimation [SEE] method) with the ROI method for preoperative SPECT to predict the hyperperfusion phenomenon (HPP) after CAS. Preoperative resting asymmetry index (cerebral blood flow [CBF] ratio from the affected to unaffected hemisphere) and cerebrovascular reactivity (CVR) to acetazolamide were measured by N-isopropyl-p-[¹²³I]-iodoamphetamine SPECT using the SEE and ROI method in 84 patients. CBF was also measured the day after CAS. Perfusion data with the highest area under the curve (AUC) by receiver-operating characteristic (ROC) analysis was considered a perfusion risk factor of HPP. Multivariate analyses for clinical characteristics and perfusion risk factors were performed to determine predictors of HPP.

RESULTS

The HPP was observed in 10 patients (11.9%). Female sex, contralateral stenosis, and degree of stenosis were significantly associated with HPP development on univariate analysis, and symptomatic stenosis was not found to be a significant factor. On SPECT analysis, CVR in the MCA area by SEE method had the highest AUC (0.981). Multivariate analysis showed that CVR in the MCA area was a significant predictor of HPP (P=0.041). To predict hyperperfusion, the ROC curve of the CVR showed a cutoff value of -0.60%, sensitivity of 94.6%, and specificity of 100% (P<0.001).

CONCLUSIONS

Objective SEE method had better a predictive capability than ROI method to identify risk of hyperperfusion after CAS.

Calcification in original plaque and restenosis following carotid artery stenting

Background:

The relationship between calcification in primary plaque and recurrent stenosis after carotid artery stenting (CAS) is not established, but an inverse association with restenosis following carotid endarterectomy (CEA) has been suggested.

Methods:

We retrospectively analyzed 75 plaques of 109 consecutive CAS with regard to calcification, using the calcium score and shape, location, and other characteristics of original plaques together with stenting-related factors. CAS was performed in a standard fashion with an embolic protection device. Greater-than-moderate restenosis (≥50%) was assessed by peak systolic velocity (PSV) with duplex ultrasonography (≥130 cm/s, internal/common carotid or distal/proximal PSV ratio ≥2.0).

Results:

Univariate analysis revealed percentages of dyslipidemia treated with statins (P = 0.03), calcification in distal ICA (P = 0.02), and immediate residual stenosis (P = 0.02) were significantly higher in patients with greater-than-moderate restenosis, whereas calcification in carotid bulb and usage of open-cell stent were rather less frequent (P < 0.001 and P = 0.02, respectively). Multivariate logistic regression analysis showed that rarity of calcification in carotid bulb was a sole independent predictor for greater-than-moderate recurrent carotid stenosis 1 year after CAS (OR = 0.21, CI = 0.06–0.77, P = 0.02).

Conclusions:

Calcium score was not significantly related to restenosis at 1 year after CAS, as was previously found following CEA, though scarcity of calcification in carotid bulb was suggested as a predictor of in-stent restenosis. Compared to post-CEA restenosis, carotid plaque calcification may be inversely but tenuously associated with recurrent stenosis 1 year post-CAS. No other stenting factors (e.g., stent design, pre-/post-dilation, or protection devices) showed a significant association with recurrent stenosis post-CAS.

Restenosis after carotid artery stenting

As a common etiology for ischemic stroke, atherosclerotic carotid stenosis has been targeted by vascular surgery since 1950s. Compared with carotid endarterectomy, carotid angioplasty and stenting (CAS) is almost similarly efficacious and less invasive. These advantages make CAS an alternative in treating carotid stenosis. However, accumulative evidences suggested that the long-term benefit-risk ratio of CAS may be decreased or even neutralized by the complications related to in-stent restenosis (ISR). Therefore, investigating the mechanisms and identifying the influential factors of ISR are of vital importance for improving the long-term outcomes of CAS. As responses to intrinsic and extrinsic injuries, intimal hyperplasia and vascular smooth muscle cell proliferation have been regarded as the principle mechanisms for ISR development. Due to the lack of consensus-based definition and consistent follow-up protocol, the reported incidences of ISR after CAS varied widely among studies. These variations made the inter-study comparisons of ISR largely illogical. To eliminate restenosis after CAS, both surgery and endovascular procedures have been attempted with promising results. For preventing ISR, drug-eluting stents and antiplatelets have been proposed as potential solutions.