Differential prediction of high-sensitivity cardiac troponin-I, but not N-terminal pro-brain natriuretic peptide, in different pitavastatin doses on cardiovascular events in stable coronary artery disease.

BACKGROUND: This study aimed to examine whether high-sensitivity cardiac troponin-I (hsTnI) and N-terminal pro-brain natriuretic peptide (NT-proBNP) could predict future major adverse cardiovascular events (MACE) in stable coronary artery disease (CAD) patients with high- or low-dose of pitavastatin. METHODS: This was a case-cohort analysis of the REAL-CAD study, a randomized trial of high- or low-dose (4 or 1 mg/day) pitavastatin therapy in patients with stable CAD. We examined the MACE risk according to the quartile of hsTnI and NT-proBNP at baseline. RESULTS: A total of 1336 and 1396 patients including 582 MACE cases were randomly examined into the hsTnI and NT-proBNP cohort, respectively. Both higher levels of hsTnI and NT-proBNP at baseline were significantly associated with increased risk of MACE (p < 0.001, respectively). When separately analyzed in statin dose, the higher marker levels were significantly associated with higher MACE risk in all cohorts (p < 0.001 in all cohorts). After multivariable adjustment, hsTnI levels were significantly associated with MACE risk in low-dose statin group (HR 2.54, p = 0.0001); however, in high-dose pitavastatin therapy, a significant association was diminished in MACE risk among the quartiles of baseline hsTnI levels (p = 0.154). Conversely in the NT-proBNP cohort, the association between NT-proBNP levels and MACE risk was constantly observed regardless of pitavastatin dose even after multivariable adjustment (both p < 0.0001). CONCLUSIONS: Patients with high hsTnI levels had high risk of MACE in low-dose statin group, but not in high-dose, suggesting that high-dose statin treatment might decrease MACE risk in stable CAD patients with high hsTnI levels.

Robotic-assisted percutaneous coronary intervention in the COVID-19 pandemic.

Coronavirus disease-2019 (COVID-19) has a profound impact on the health care system worldwide. In the COVID-19 pandemic, hospitals are required to halt elective surgeries and procedures for preventing nosocomial infections and saving medical resources. In these situations, emergency procedures are required for life-threatening cardiovascular diseases such as acute coronary syndrome and cardiogenic shock. To prevent the spread of COVID-19, a social distance is essentially required. In ordinary percutaneous coronary intervention (PCI), operators manipulate the devices standing at the patient's tableside during the whole procedure, which may involve a certain risk of exposure to patients with COVID-19. A robotic-assisted PCI (R-PCI) allows operators to manipulate devices remotely, sitting at a cockpit located several meters away from the patient, and in addition, the assistant can be at the foot of the bed, much further from the access site. R-PCI can help to minimize the radiation exposure and the amount of person-to-person contact, and consequently may reduce the risk for the exposure to the virus.

Consensus document on the standard of coronary angioscopy examination and assessment from the Japanese Association of Cardiovascular Intervention and Therapeutics.

Coronary angioscopy (CAS) is a unique diagnostic device that allows direct visualization of the vascular luminal surface in living patients. CAS contributes to elucidate the pathology of coronary artery disease. This consensus document provides a standard for CAS examination and assessment.

Successful introduction of robotic-assisted percutaneous coronary intervention system into Japanese clinical practice: a first-year survey at single center.

In Japan, a robotic-assisted PCI (R-PCI) system, the CorPath GRX System (Corindus Inc.), has been approved for clinical use in 2018, which is the first introduction of R-PCI into Japan. In this study, the clinical performance of the R-PCI system in the initial year at Kurume University Hospital was evaluated comparing with conventional manual PCI (M-PCI). A total of 30 R-PCI and 77 M-PCI procedures performed between April 2019 and March 2020, were retrospectively included. The primary outcome was the rate of clinical success defined as < 30% residual stenosis without in-hospital major adverse cardiovascular events (MACE). The secondary outcomes were fluoroscopy time, dose area product (DAP), amount of radiation exposure to operators and assistants, procedural time, and contrast volume. Propensity-matching technique was used to match each R-PCI lesion to the nearest M-PCI lesion without replacement. After propensity score matching, 30 R-PCI procedures in 28 patients and 37 M-PCI procedures in 35 patients were analyzed. Clinical success rate with R-PCI was favorable and comparable to M-PCI (93.3 vs. 94.6%, p = 0.97), without any in-hospital MACE. The operator radiation exposure was significantly lower in R-PCI (0 vs. 24.5 µSV, p < 0.0001). Radiation exposure to the patients was tended to be reduced by R-PCI (DAP: 77.6 vs. 100.2 Gycm2, p = 0.07). There were no statistically significant differences in radiation exposure to the assistant, fluoroscopy time, procedural time and contrast volume between the two groups (radiation exposure to the assistant: 10.5 vs. 10.0 µSV, p = 0.64, fluoroscopy time: 27.5 vs. 30.1 min, p = 0.55, procedural time: 72.4 vs. 61.6 min, p = 0.23, and contrast volume: 93.2 vs. 102.0 ml, p = 0.36). R-PCI in selected patients demonstrated favorable clinical outcomes with dramatical reduction of radiation exposure to operators.

Differences in clinical outcomes between pre- and post-marketing clinical study following paclitaxel-coated balloon catheter treatment for coronary in-stent restenosis: from the Japanese regulatory viewpoint.

In 2013, a drug-coated balloon catheter (DCB) (SeQuent Please) for the treatment of coronary in-stent restenosis (ISR) was approved in Japan. The pre-marketing Japan domestic NP001 study demonstrated better outcomes of the DCB (n = 138) compared to plain balloon angioplasty (n = 72). After the introduction to marketing, a post-marketing surveillance (PMS) (n = 396) was conducted to evaluate the safety and efficacy of the DCB in Japanese routine clinical practice. The aim of this paper was to assess differences between the pre-marketing NP001 study and the PMS. Compared to the NP001 study, more complex lesions were treated in the PMS (type B2/C: 69.0% vs 20.4%, total occlusion: 11.2% vs 0%, p < 0.001, respectively) and target lesion was more frequently ISR related to drug-eluting stent (DES) (79.5% vs 39.4%, p < 0.001). Regarding clinical outcomes, the rate of target lesion revascularization (TLR) was higher in the PMS than in the NP001 study (TLR: 12.9% at 7 months and 17.6% at 12 months vs 2.8% at 6 months, p = 0.001, p < 0.001, respectively). Multivariable logistic regression analysis revealed that DES-ISR was a risk factor of TLR after DCB treatment for ISR (odds ratio: 5.77, 95% CI 1.75-18.95, p = 0.004). Among representative published trials using DCB for ISR, clinical outcomes are often worse in DES-ISR trials than those in bare metal stent-ISR trials. The rates of TLR in previous DES-ISR trials are similar to that in the current PMS (TLR at 12 months: 22.1% for ISAR-DESIRE 3, 15.3% for PEPCAD-DES, and 13.0% for RIBS IV). The effectiveness and safety of DCB for coronary ISR have been confirmed in the Japanese real-world survey. PMS would be useful to evaluate the safety and effectiveness of medical products throughout their total life cycles.

Recent Least Burdensome Approach for the Approval of Innovative Medical Devices in Japan -Regulatory Approval Review of an Everolimus-eluting Bioresorbable Scaffold.

Although a domestic trial in Japan revealed that Absorb bioresorbable vascular scaffold (BVS) has no inferiority to everolimus-eluting stent (EES) cohort in the primary endpoint of the target lesion failure at 12 months, the scaffold/stent thrombosis (ST) rates with the BVS at 24 months were higher than those with the EES (Absorb BVS 3.1% vs. EES 1.5%), the ST rate of 3.1% with Absorb BVS is not an acceptable level in Japan. A cause-of-ST analysis revealed that cases in which diagnostic imaging and ensuing post-dilatation had been performed appropriately had lower ST rates than those without such management (within 1 year: 1.37% vs. 7.69%, from 1 to 2 years: 0.00% vs. 8.33%). Therefore, a further evaluation was needed to confirm that the ST rate with the Absorb BVS would be reduced by a proper implementation procedure. Regulatory approval was given conditionally to initiate rigorous post-marketing data collection in order to ensure the proper use of this device in limited facilities. The One-year Use-Result Survey in Japan for the Absorb BVS revealed no instances of ST. This approach to reducing the premarket regulatory burden of clinical trials and enhancing the post-marketing commitments of medical device regulation is useful for expediting patient access to innovative medical devices.

Trial Design Principles for Patients at High Bleeding Risk Undergoing PCI: JACC Scientific Expert Panel.

Investigating the balance of risk for thrombotic and bleeding events after percutaneous coronary intervention (PCI) is especially relevant for patients at high bleeding risk (HBR). The Academic Research Consortium for HBR recently proposed a consensus definition in an effort to standardize the patient population included in HBR trials. The aim of this consensus-based document, the second initiative from the Academic Research Consortium for HBR, is to propose recommendations to guide the design of clinical trials of devices and drugs in HBR patients undergoing PCI. The authors discuss the designs of trials in HBR patients undergoing PCI and various aspects of trial design specific to HBR patients, including target populations, intervention and control groups, primary and secondary outcomes, and timing of endpoint reporting.

Independent Factors for In-Hospital Death Following Drug-Eluting Stent Thrombosis From the Japanese Adverse Event Report System.

BACKGROUND: Stent thrombosis (ST) is a serious complication after drug-eluting stents (DES) implantation. To identify the risk factors of mortality following ST, we evaluated adverse event reports used for safety measures after approval.Methods and Results:Between July 2004 and August 2019, 2,887 ST case reports were submitted to the Pharmaceutical and Medical Device Agency. Reports of probable or possible ST (n=604), with insufficient data regarding in-hospital outcome or duration between procedure and ST occurrence (n=37) or duplicate reports (n=191) were excluded. Accordingly, 2,045 reports with definite ST were analyzed. Among the subjects, there were 286 in-hospital deaths (14.0%). Multivariate logistic regression analysis revealed that left main trunk (LMT) (odds ratio [OR]: 4.76, 95% confidence interval [CI]: 3.26-6.96), chronic heart failure (CHF) (OR: 2.88, 95% CI: 1.61-5.14), hemodialysis (OR: 2.69, 95% CI: 1.66-4.36), prior stroke (OR: 2.28, 95% CI: 1.15-4.51), over 70 years old (OR: 1.62, 95% CI: 1.22-2.16), and right coronary artery (OR: 0.41, 95% CI: 0.27-0.63) were independent factors for in-hospital death after DES-ST. CONCLUSIONS: LMT, CHF, hemodialysis, prior stroke, and older age were independently associated with higher risk of in-hospital death following DES-ST. If target patients have these factors, maximum preventive strategies against ST occurrence, including adequate dual-antiplatelet therapy duration and optimal DES deployment procedures, are required.

Patient and lesion characteristics in late/very late stent thrombosis with everolimus-eluting stents from real-world adverse event reporting.

BACKGROUND: Stent thrombosis (ST) is a rare but serious complication after deployment of a drug-eluting stent. The features of ST after implantation of an everolimus-eluting stent (EES) have not been fully elucidated. METHODS: A comprehensive survey of real-world adverse event reporting with conditions for approval under the Pharmaceuticals and Medical Devices Act identified 490 cases of ST with EES. A total of 370 patients with definite ST after EES implantation [287 with early (E)ST (within 30 days), 54 with late (L)ST (31-365 days), and 29 with very late (VL)ST (over 1 year)] were divided into an EST group and an LST/VLST group to compare the patients and lesions characteristics. RESULTS: The frequency of patients with hemodialysis and in-stent restenosis (ISR) lesions were significantly higher in the LST/VLST group than in the EST group (hemodialysis, 22.9% vs 2.7%, p = 0.0001; ISR lesions, 25.9% vs 9.4%, p = 0.0001). Characteristic demographic factors for LST/VLST versus EST identified by multivariable model were hemodialysis and ISR lesions (hemodialysis: odds ratio 7.348, 95% confidence interval 2.458-21.968, p = 0.0001; ISR lesions: odds ratio, 2.490, 95% confidence interval 1.100-5.638, p = 0.027). The in-hospital death rates from ST were not significantly different between the EST group and the LST/VLST group (EST, 15% vs LST/VLST, 21.7%, p = 0.147). CONCLUSIONS: Patient-related and lesion-related characteristics were significantly different between EST and LST/VLST. Data collection from adverse event reporting could be a helpful strategy for evaluation of this serious but rare complication.

Low ankle brachial index predicts poor outcomes including target lesion revascularization during the long-term follow up after drug-eluting stent implantation for coronary artery disease.

BACKGROUND: Peripheral arterial disease (PAD) frequently coexists with coronary artery disease (CAD). The ankle-brachial index (ABI) is widely used for the screening for PAD. Low ABI is associated with short-term clinical outcomes in patients receiving coronary drug-eluting stent (DES) implantation. However, there is no report to examine the relationship between lower ABI and long-term clinical outcomes after DES implantation. Thus, we investigated the clinical long-term impact of low ABI after DES implantation. METHODS: This retrospective analysis included 181 CAD patients treated with DES from April 2010 to March 2013 in our institute. Based on ABI values, we divided the subjects into the low-ABI group　(ABI<0.9, n=29) and the normal ABI group　(0.9≤ABI<1.4, n=152). The incidence of target lesion revascularization (TLR), all-cause mortality, and major adverse cardiac and cerebrovascular events (MACCE) defined as a composite of cardiac death, myocardial infarction, stroke, and any repeat revascularization, were compared between the 2 groups. RESULTS: During the median follow-up period of 43 months, the incidences of TLR, all-cause mortality, and MACCE were significantly higher in the low ABI group than in the normal ABI group (TLR: 41.4% vs 9.9%, p<0.001, all-cause mortality: 31.0% vs 3.9%, p<0.001, MACCE: 48.3% vs 11.2%, p<0.001, respectively). CONCLUSIONS: Low ABI may predict poor long-term outcomes, including TLR, in CAD patients treated with DES.

First Experience of Robotic-assisted Percutaneous Coronary Intervention in Japan.

In 2018, the CorPath GRX system (Corindus) was approved for use in Japan, marking the introduction of the first robotic-assisted system for percutaneous coronary intervention (PCI) in the country. The present report describes the first experience of robotic-assisted PCI for four coronary lesions in two cases in a single center. All procedures succeeded without any complications, although one procedure was converted to manual PCI by the operator's decision. Post-marketing surveillance to assess the impact of this novel system on both Japanese patients and physicians is currently ongoing in Japan.

Defining High Bleeding Risk in Patients Undergoing Percutaneous Coronary Intervention.

Identification and management of patients at high bleeding risk undergoing percutaneous coronary intervention are of major importance, but a lack of standardization in defining this population limits trial design, data interpretation, and clinical decision-making. The Academic Research Consortium for High Bleeding Risk (ARC-HBR) is a collaboration among leading research organizations, regulatory authorities, and physician-scientists from the United States, Asia, and Europe focusing on percutaneous coronary intervention-related bleeding. Two meetings of the 31-member consortium were held in Washington, DC, in April 2018 and in Paris, France, in October 2018. These meetings were organized by the Cardiovascular European Research Center on behalf of the ARC-HBR group and included representatives of the US Food and Drug Administration and the Japanese Pharmaceuticals and Medical Devices Agency, as well as observers from the pharmaceutical and medical device industries. A consensus definition of patients at high bleeding risk was developed that was based on review of the available evidence. The definition is intended to provide consistency in defining this population for clinical trials and to complement clinical decision-making and regulatory review. The proposed ARC-HBR consensus document represents the first pragmatic approach to a consistent definition of high bleeding risk in clinical trials evaluating the safety and effectiveness of devices and drug regimens for patients undergoing percutaneous coronary intervention.

Defining high bleeding risk in patients undergoing percutaneous coronary intervention: a consensus document from the Academic Research Consortium for High Bleeding Risk.

Identification and management of patients at high bleeding risk undergoing percutaneous coronary intervention are of major importance, but a lack of standardization in defining this population limits trial design, data interpretation, and clinical decision-making. The Academic Research Consortium for High Bleeding Risk (ARC-HBR) is a collaboration among leading research organizations, regulatory authorities, and physician-scientists from the United States, Asia, and Europe focusing on percutaneous coronary intervention-related bleeding. Two meetings of the 31-member consortium were held in Washington, DC, in April 2018 and in Paris, France, in October 2018. These meetings were organized by the Cardiovascular European Research Center on behalf of the ARC-HBR group and included representatives of the US Food and Drug Administration and the Japanese Pharmaceuticals and Medical Devices Agency, as well as observers from the pharmaceutical and medical device industries. A consensus definition of patients at high bleeding risk was developed that was based on review of the available evidence. The definition is intended to provide consistency in defining this population for clinical trials and to complement clinical decision-making and regulatory review. The proposed ARC-HBR consensus document represents the first pragmatic approach to a consistent definition of high bleeding risk in clinical trials evaluating the safety and effectiveness of devices and drug regimens for patients undergoing percutaneous coronary intervention.

Regulatory approval review of transcatheter mitral valve repair - Difference in the indication between the USA and Japan.

The indication for MitraClip (Abbott Vascular, Santa Clara, CA, USA) in the USA is degenerative mitral regurgitation (DMR), but the Japanese indication includes both DMR and functional mitral regurgitation (FMR), in patients without severe left ventricular dysfunction. One of the reasons for this difference is that the Japanese Circulation Society submitted a formal request to the Japanese government for early approval of MitraClip for both DMR and FMR on the basis of unmet medical need for MR patients resistant to medical therapy, but at prohibitive risk for mitral valve surgery. Here, we describe the regulatory approval review process of MitraClip in Japan. Clinical data from outside Japan indicated that MitraClip provides significant improvements from baseline in New York Heart Association Class and hospitalizations for heart failure due to the reduction of MR grade without adversely affecting long-term prognosis in FMR patients as well as DMR patients. Also, a Japanese domestic trial showed a favorable acute procedural success rate without serious adverse events with MitraClip in both DMR and FMR patients. Further, it is considered in Japan that improvement of MR mechanically is clinically important in both DMR and FMR, in patients without severe left ventricular dysfunction. On the basis of these considerations, the MitraClip was approved in Japan for indications of both DMR and FMR with preserved cardiac function in patients at prohibitive risk for mitral valve surgery.

An intravascular magnetic wire for the high-throughput retrieval of circulating tumour cells in vivo.

The detection and analysis of rare blood biomarkers is necessary for early diagnosis of cancer and to facilitate the development of tailored therapies. However, current methods for the isolation of circulating tumour cells (CTCs) or nucleic acids present in a standard clinical sample of only 5-10 ml of blood provide inadequate yields for early cancer detection and comprehensive molecular profiling. Here, we report the development of a flexible magnetic wire that can retrieve rare biomarkers from the subject's blood in vivo at a much higher yield. The wire is inserted and removed through a standard intravenous catheter and captures biomarkers that have been previously labelled with injected magnetic particles. In a proof-of-concept experiment in a live porcine model, we demonstrate the in vivo labelling and single-pass capture of viable model CTCs in less than 10 s. The wire achieves capture efficiencies that correspond to enrichments of 10-80 times the amount of CTCs in a 5-ml blood draw, and 500-5,000 times the enrichments achieved using the commercially available Gilupi CellCollector.

Dose-Dependent Cardioprotection of Moderate (32°C) Versus Mild (35°C) Therapeutic Hypothermia in Porcine Acute Myocardial Infarction.

OBJECTIVES: The study investigated whether a dose response exists between myocardial salvage and the depth of therapeutic hypothermia. BACKGROUND: Cardiac protection from mild hypothermia during acute myocardial infarction (AMI) has yielded equivocal clinical trial results. Rapid, deeper hypothermia may improve myocardial salvage. METHODS: Swine (n = 24) undergoing AMI were assigned to 3 reperfusion groups: normothermia (38°C) and mild (35°C) and moderate (32°C) hypothermia. One-hour anterior myocardial ischemia was followed by rapid endovascular cooling to target reperfusion temperature. Cooling began 30 min before reperfusion. Target temperature was reached before reperfusion and was maintained for 60 min. Infarct size (IS) was assessed on day 6 using cardiac magnetic resonance, triphenyl tetrazolium chloride, and histopathology. RESULTS: Triphenyl tetrazolium chloride area at risk (AAR) was equivalent in all groups (p = 0.2), but 32°C exhibited 77% and 91% reductions in IS size per AAR compared with 35°C and 38°C, respectively (AAR: 38°C, 45 ± 12%; 35°C, 17 ± 10%; 32°C, 4 ± 4%; p < 0.001) and comparable reductions per LV mass (LV mass: 38°C, 14 ± 5%; 35°C, 5 ± 3%; 32°C 1 ± 1%; p < 0.001). Importantly, 32°C showed a lower IS AAR (p = 0.013) and increased immunohistochemical granulation tissue versus 35°C, indicating higher tissue salvage. Delayed-enhancement cardiac magnetic resonance IS LV also showed marked reduction at 32°C (38°C: 10 ± 4%, p < 0.001; 35°C: 8 ± 3%; 32°C: 3 ± 2%, p < 0.001). Cardiac output on day 6 was only preserved at 32°C (reduction in cardiac output: 38°C, -29 ± 19%, p = 0.041; 35°C: -17 ± 33%; 32°C: -1 ± 28%, p = 0.041). Using linear regression, the predicted IS reduction was 6.7% (AAR) and 2.1% (LV) per every 1°C reperfusion temperature decrease. CONCLUSIONS: Moderate (32°C) therapeutic hypothermia demonstrated superior and near-complete cardioprotection compared with 35°C and control, warranting further investigation into clinical applications.

Assessment of bioresorbable scaffold with a novel high-definition 60 MHz IVUS imaging system: Comparison with 40-MHz IVUS referenced to optical coherence tomography.

BACKGROUND: In vivo assessment of bioresorbable scaffold (BRS) is of growing clinical interest. The novel 60MHz high-definition intravascular ultrasound (HD-IVUS) has been developed to overcome the limitations of conventional 40 MHz IVUS. This study aimed to evaluate the performance and limitations of 60 MHz HD-IVUS compared with 40 MHz IVUS with respect to polymeric-strut visualization, quantitative and qualitative analysis, and feasibility of high-speed pullback in the assessment of BRS. METHODS AND RESULTS: In a bench-test model, 361 struts were analyzed to evaluate the influence of ultrasound-beam angles and proximity of adjacent struts on IVUS visualization of BRS struts. Various settings were created by deforming the BRS and positioning the transducer offcenter. In an in vivo swine coronary model, scaffold and lumen areas, degree of visible external elastic membrane, incomplete strut apposition, and strut fracture were evaluated in 59 matched cross-sections obtained at conventional (0.5 mm/sec) and high speed (10 mm/sec) pullbacks. Both studies utilized optical coherence tomography (OCT) as reference. Overall, 60 MHz HD-IVUS demonstrated significantly improved visualization of polymeric struts compared with 40 MHz IVUS (well-visualized: 84.5% vs 62.3%, not visible: 4.4% vs 13.9%, respectively. P < 0.001), which was less affected by the beam angle and adjacent strut proximity. In the in vivo model, 60-MHz HD-IVUS showed better agreement of area measurements and strut abnormalities with OCT than 40 MHz IVUS. These findings were also confirmed on high-speed pullback images of 60 MHz HD-IVUS. CONCLUSION: As referenced to OCT, this study showed superiority of 60 MHz HD-IVUS over 40 MHz IVUS in the assessment of BRS with feasibility of high-speed pullback imaging.

Differences in Vascular Response between Balloon Overstretch and Stent Overexpansion in Nonatherosclerotic Porcine Coronary Arteries.

Which preclinical models are best suited for restenosis research remains uncertain. Here we compared the restenotic responses after balloon or stent overstretch injury in a porcine coronary artery. A total of 30 coronary lesions in 5 pigs were treated by balloon overdilatation or oversized stent implantation at various balloon-to-artery (B:A) ratios. Four weeks later, the lesions were examined in vivo by using coronary angiography, intravascular ultrasound, and optical coherence tomography (OCT). At follow-up, the lumen area stenosis and plaque burden at the minimal lumen area site were greater in stented sites than in balloon injury site (lumen area stenosis, 21.7 ± 8.9% compared with 32.8 ± 12.1%; plaque burden, 30.1% ± 10.1% compared with 44.7% ± 10.1%, respectively). The remodeling index was significantly smaller for the balloon-injury group than the stent group (0.86 ± 0.11 compared with 1.00 ±0.04). Only the stent group that was dilated at a high B:A ratio resulted in increased plaque burden. In the balloon-injury sites, high B:A ratios were significantly associated with greater negative remodeling. Tissue morphology assessment by OCT revealed that the predominant pattern in balloon injury sites was homogeneous, whereas that in stented sites was a layered to heterogeneous pattern. Neointimal proliferation was significantly greater after oversized stenting than after balloon overstretch injury. Together these findings suggest that stent overexpansion of porcine coronary arteries might be appropriate for researching restenosis than is the balloon overstretch injury model.