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CARDIOLOGY

Progress in the application of intravascular imaging in the diagnosis and treatment of coronary heart disease

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Expert introduction:
Jia Haibo, chief physician, professor, doctoral tutor, winner of the National Outstanding Youth Science Fund (2017), is currently the deputy director of the Department of Cardiology, the Second Affiliated Hospital of Harbin Medical University.He graduated from Harbin Medical University with a Ph.D. degree from the famous cardiovascular disease expert Yu Bo in China. He studied at Harvard Medical School for 3 years.Mainly engaged in coronary heart disease interventional treatment and intravascular imaging and functional clinical, teaching and research work.The rapid development of intracavitary imaging technology has greatly promoted the improvement of coronary interventional therapy and has become an indispensable part of the cardiovascular field.In the upcoming 2018, intravascular imaging has a number of hot events that may change future clinical practice in the study of coronary heart disease mechanisms, treatment guidance and strategy optimization. The annual events of the latest progress in intravascular imaging are now being counted.(1) The first intracavitary imaging clinical application expert consensus developed by the European Association of Cardiovascular Interventions (EAPCI) and the Chinese Medical Association Cardiovascular Disease Branch (CSC) released a number of previous reports on OCT (optical coherence tomography) and IVUS (vascularThe consensus of internal ultrasound) has made detailed specifications for the application, measurement and definition of the two technologies, but it is mainly based on theory and does not provide authoritative answers to practical problems in clinical practice.Based on the evidence-based medical evidence, combined with the opinions of the expert group, the clinical intervention doctors answered the five questions that are currently the most concerned.1. Can intravascular imaging improve the clinical outcome after PCI?The Consensus Expert Group combined a number of evidence-based medical evidence that IVUS and OCT are not weaker or even better than the “gold standard” coronary angiography in guiding and optimizing PCI.Both intraluminal imaging techniques can identify the advantages and disadvantages of stent implantation (stent expansion, adherence and complications), and can be studied in depth from the mechanism of stent failure.2. Which type of patients and lesions should be examined for intravascular imaging in PCI?The optimization of treatment strategy and stent placement is the main basis for the clinical application of intracavitary imaging, which is the main guiding significance of the current application, and is generally recognized by experts at home and abroad.Consensus: Patients diagnosed with ACS, left main lesions, bifurcation lesions with dual stent technique, bioabsorbable stent implantation, and renal insufficiency are the primary indications for intracavitary imaging.3. What are the criteria for IVUS and OCT in guiding and optimizing stent placement?Consensus from the pre-PCI, intraoperative, postoperative multi-angle, multi-faceted description of the application of intracavitary imaging in stent implantation and optimization, including: 1) recognition of plaque composition before PCI; 2)Selection of optimal stent size during intervention; 3) Evaluation of postoperative stent implantation effect 4. How to evaluate the cause of stent failure?Intravascular imaging analysis of the causes of in-stent restenosis and stent thrombosis is the key to elucidating stent failure (highly recommended); OCT is the preferred technique for elucidating the mechanism of in-stent restenosis and stent thrombosis;When the cause is not clear, the application of intracavity imaging should be considered and must be applied and recommended for evaluating any new DES or BRS stent failure.The OCT results of the series of stent thrombosis studies suggest that the following causes of stent failure can be prevented: poor stent attachment, large plaque load on the stent, and poor expansion of the sandwich and stent.5. What are the limitations of intracavity imaging?A major limitation of intravascular imaging is that imaging itself requires additional time. The cost of IVUS and OCT is also a concern, and this is a limitation recognized by most intervention experts.In a large study, more than 3,600 OCT or IVUS-guided PCI were enrolled, and the results showed that imaging-related complications were very rare (0.6%), self-limiting, or simply treated.Does not cause serious adverse cardiovascular events.The consensus is based on the most controversial clinical problems. Based on the existing evidence-based medical evidence, the clinical practitioners have answered practical questions and have great clinical reference and guiding value.(II) Prediction of plaque erosion in the EROSION series: smoking, age <50 years old, female patients, and other risk factors for coronary heart disease are prone to plaque erosion. Patients with myocardial infarction caused by plaque erosion (PE)Non-stent treatment strategy is initially proven to be safe and reliable after opening blood flow. Although the long-term safety is still further confirmed by subsequent large-scale follow-up clinical trials, the individualization of non-stent plaque erosion patientsThe precise treatment mode breaks the current treatment concept of conventional stent implantation for patients with myocardial infarction, and it is in line with the concept of modern precise individualized treatment.Whether plaque erosion patients have predictable population characteristics, thus achieving secondary prevention to primary prevention transformation, is still a clinical problem to be solved.Our team performed a pre-interventional OCT examination of prospectively selected 822 STEMI patients. Under the established diagnostic criteria, 209 patients with PE (25.4%) and 564 patients with PR (68.6%) were enrolled.The rate was higher (p=0.009), and men had a similar but not obvious trend (p=0.011). PE was highly developed in smokers and had a lower risk factor for coronary heart disease. At the site of the disease, LAD (61.2%)Most of them, and plaque rupture mainly occurred in LAD (47%) and right crown (43.3%).Despite a similar lesion length, plaque rupture was more common in the bifurcation (p < 0.001).Multivariate regression analysis confirmed that a quarter of ACS was first caused by plaque erosion in the population, age <50 years, smoking, no other risk factors for coronary heart disease, single vessel disease, mild lesions, residual lumen areaLarge, lesions close to the branch are significantly associated with plaque erosion; for male patients, smoking and lesions close to the branch are the most important factors associated with plaque erosion. Among female patients, age <50 years (premenopausal) predicts the highest value of plaque erosion..A large sample analysis of clinical, angiographic and OCT features of PE patients revealed that PE is a predictable population in patients with ACS, thus establishing a precise PE warning model, which makes the prevention and treatment front of PE patients advance and improves the prevention of PE patients.The precise treatment system for diagnosis and treatment, the basis of the anti-diagnosis system has realized the transformation from clinical manifestation to pathological mechanism.(C) OCT, IVUS and traditional coronary angiography, the three guide PCI is better than the traditional coronary angiography is still the gold standard for the diagnosis of coronary heart disease, but with the continuous development of medical technology, the implementation of individualized precision treatment conceptContinuous enhancement, the shortcomings of coronary angiography to identify only two-dimensional images of coronary vessels are gradually revealed, and intracavitary imaging techniques can accurately evaluate the fine structure of coronary lumens, not only to evaluate the degree of lumen stenosis, but alsoEvaluation of other refined structures such as plaque load and vulnerability is of great clinical significance for exploring the pathogenesis of coronary heart disease and optimizing the interventional treatment of coronary heart disease.As the most promising two intracavitary imaging techniques, OCT and IVUS have their own advantages and disadvantages in scientific research and clinical applications. However, the prognosis of both patients with PCI and OCU is still a hot topic in clinical practice..A cohort study based on the Pan-London (UK) PCI registry included 123,764 patients who underwent PCI at the National Health Service Hospital in London from 2005 to 2015.After exclusion of patients receiving emergency PCI, 87 166 patients were eventually enrolled.The primary endpoint was all-cause mortality (median follow-up of 4.8 years).1149 (1.3%) patients used OCT, 10 971 (12.6%) patients used intravascular ultrasound (IVUS), and the remaining 75 046 patients used angiography alone.The total OCT usage increased over time (P < 0.0001) and the different central growth rates were different (P = 0.002).The average stent length was the shortest in the angiographic guidance group, the IVUS guidance group was longer, and the OCT guidance group was the longest.OCT-guided surgery has a higher success rate and can reduce the in-hospital MACE rate.There were significant differences in mortality between OCT-guided PCI patients (7.7%) compared with IVUS guidance (12.2%) or angiographic guidance (15.7%; P < 0.0001).Overall, this difference was in multivariate Cox analysis (HR = 0.48; 95% CI: 0.26 to 0.81; P = 0.001) and propensity matching (HR = 0.39; 95% CI: 0.21 to 0.77; P = 0.0008; OCT)After vs. angiography, there was no difference in the matched OCT and IVUS groups (HR=0.88; 95% CI: 0.61 to 1.38; P=0.43).This large observational study suggests that OCT-guided PCI is associated with improved surgical outcomes, in-hospital events, and long-term survival compared with standard angiographically guided PCI.Another ULTIMATE study enrolled 1448 patients and was randomized to the IVUS guidance group and the coronary angiography group with a ratio of 1;1.During the follow-up of 12 months, 60 patients (4.2%) developed TVFs, 21 patients (2.9%) in the IVUS group, and 39 patients (5.4%) in the angiography group (HR: 0.530, 95% CI: 0.312 - 0.901; p = 0.019).In the IVUS group, 1.6% of successful surgical patients recorded TVF, compared with 4.4% of patients who failed to meet all the best criteria (TV: 0.349; 95% CI: 0.135-0.898; p =0.029).Based on the analysis of IVUS at the lesion level, clinical factors led to a significant reduction in target lesion revascularization (TLR) or definite stent thrombosis (HR: 0.407; 95% CI: 0.188-0.880; p=0.018).Within the larger population, IVUS-guided PCI treatment reduced the incidence of postoperative adverse events, superior to coronary angiography, providing evidence-based medical evidence for a broader clinical application of IVUS.Whether intraluminal imaging technology can eventually replace coronary angiography, or only as a supplementary diagnosis and treatment, will be further answered by future clinical trials.In addition, as a follow-up study to the ILUMIEN series, the ILUMIEN IV trial began to enroll patients this year. The study will be the largest randomized trial in the field of intracavitary imaging to guide clinical PCI, evaluating OCT, IVUS to guide the clinical effects of PCI, for furtherThe clinical application provides evidence-based medical evidence.Previous studies have shown that IVUS-assisted PCI can effectively reduce severe cardiovascular adverse events (MACE) after PCI and has been widely used in clinical practice.OCT has higher resolution than IVUS, can analyze finer structure gold, has better clinical guidance, and will give an answer through further clinical trials in the future.(4) LRP study: NIRS has a promising future in predicting ACS prognosis Professor Ron Waksman published the latest LRP study results at the TCT 2018 conference, demonstrating the uninterrupted non-blood flow-limited lipids detected by NIRS-IVUS imagingThe presence of plaque is associated with major adverse cardiovascular events (MACE).Coronary artery-rich lipid plaques may be associated with subsequent cardiovascular events, and can be used to identify high-risk groups and lipid-rich vulnerable plaques, and appropriate interventions can effectively improve the clinical outcome of PCI patients.The NIRS-IVUS has a dual-modal imaging catheter that simultaneously evaluates the lipid content of the plaque and the plaque load, allowing for risk stratification and judgment.The study enrolled a total of 1563 patients with suspected coronary artery disease who underwent cardiac catheterization from 44 centers in the United States and Europe from February 2014 to March 2016. Imaging was performed in two or more arteries by NIRS-IVUS.Patient levels and plaque level events were observed over 2 years.All follow-up patients had at least one maxLCBI 4 mm segment ≥ 250 and 50% randomized patients with all maxLCBI 4 mm segments <250.In the analysis of susceptible patients, for every 100 units increase in maxLCBI 4 mm, the risk of a non-culprit lesion MACE event within 24 months was greater than 18%.The MACE rate for patients with maxLCBI 4 mm ≥ 400 was 12.6%, compared with 6.3% for maxLCBI 4 mm < 400 patients.In the vulnerable plaque level analysis, for every 100 units increased by maxLCBI 4 mm, the risk of events in the coronary segments was greater than 45% within 24 months.The MACE rate of maxLCBI 4 mm ≥ 400 plaques was 3.7%, while the plaques of maxLCBI 4 mm 400 were 0.8%.Professor Ron Waksman of the MedStar Cardiovascular Institute in Washington, DC, said that multi-vascular NIRS can be easily and safely performed to assess and identify susceptible patients and vulnerable plaques, and NIRS imaging can identify and act as mild or non-risk patients with high-risk events.Tools for obstructive coronary and non-criminal arterial examination should be considered for patients undergoing cardiac catheterization for viable PCI.(V) MINOCA (non-obstructive myocardial infarction) exploration: the first use of OCT combined with MRI to reveal its pathogenesis Currently, many studies focus on the prognosis and treatment of MINOCA patients, but the research on MINOCA mechanism is still lacking.In fact, MINOCA is a heterogeneous disease with many underlying causes, and atherosclerosis is one of the important pathogenesis.However, the specific pathogenesis of MINOCA is still an unknown field.OCT relies on its high resolution or an imaging technique that effectively identifies the etiology of MINOCA.The study was eventually enrolled in 38 patients (mean age 62 ± 13 years, 55% female, 39% ST-segment elevation myocardial infarction).The most important point of coronary lesions was stenosis 35%, and 5 patients (13%) had normal coronary angiography results.There were 9 cases (24%) with plaque disruption [including plaque rupture (PR) and calcified nodules (CN)], and 7 cases (18%) with coronary thrombosis.Of the 31 patients, 16 (52%) had LGE and 7 (23%) had ischemic LGE.Ischemic LGE was more common in patients with plaque destruction (50% vs. 13%, p=0.053) and coronary thrombosis (67% vs. 12%, p=0.014).IRA was associated with non-IRA plaque destruction (40% vs. 6%, p=0.02), thrombosis (50% vs. 4%, p=0.014), and thin fiber cap plaque (70% vs. 30%,p=0.03) The incidence is higher.This study found that 24% and 18% of patients with MINOCA had plaque destruction and thrombosis.In addition, plaque destruction and thrombosis have been found to be associated with smoking and higher maximal stenosis, which provides clues to the pathogenesis of some patients with MINOCA and suggests whether smoking and mild to moderate CAD can be used asIt is necessary to further clarify whether there are important signs of plaque destruction and/or thrombosis.At present, CMR has a high diagnostic value for detecting myocardial fibrosis, and has become the gold standard for detecting myocardial infarction.In addition, based on the precise location of the infarct area on the CMR, CMR can directly establish the association between the offender's blood vessels and the myocardial infarct area.This study found that patients with plaque destruction or thrombosis were more likely to develop ischemic LGE, with the latter being statistically significant. In addition, plaque destruction (caused by PR), thrombosis, and IRA were compared with non-IRA.Thin fiber cap atherosclerosis changes are common, suggesting that atherosclerosis may be the pathological basis of MINOCA.However, it is worth noting that the number of entries in this experiment is small and the statistical persuasiveness is small.(VI) New applications in the field of heart transplantation: Early warning and early prevention of heart transplantation has become an effective means of rescue for end-stage heart failure, saving tens of thousands of lives.However, heart transplantation still faces many difficulties, and there is a failure rate that cannot be ignored, such as CAV heart graft vascular disease (CAV). The incidence of CAV is more than 50% after 5 years of transplantation, which affects patients far away.The main factor of prognosis.Due to the denervation of the transplanted heart, CAV patients lack typical symptoms.Therefore, coronary angiography is usually used to regularly screen for CAV and to provide timely treatment.However, due to the limitations of the method itself, coronary angiography has a poor diagnostic ability for early stage or mild CAV, so it has been clinically looking for a technique that can effectively detect early CAV instead of coronary angiography, and OCT relies on it.High resolution and identification of the fine structure of the lumen wall are expected to stand out in many intracavity imaging techniques.The study analyzed 110 OCT images from 76 patients.Of the 110 cases, there were 26 cases of intimal thickening, 11 of which were severely thickened (0.4 mm). It is worth noting that 8 cases of angiography were normal.The angiography of 5 patients with I/M CSA (ratio of intimal to medial cross-sectional area) ≥ 2 was normal.The maximum intima thickness ≥ 0.25 mm is 24%, and the maximum intima thickness ≥ 0.40 mm is 10%.The average I/M CSA ≥ 1 in 80% of cases.The I/M CSA ratio was significantly lower in the statin-treated group than in the non-statin-treated group (P=0.03).17% of cases have changed clinical treatment strategies due to OCT findings.OCT provides important information that is lacking in coronary angiography, and may be able to effectively detect early signs of CAV. This provides an early warning for CAV and provides an early warning. Early warning of CAV can be reduced by changing the treatment strategy for transplant patients.The incidence of CAV improves the quality of life of patients with end-stage heart failure.However, the statistical convincingness of this study is not sufficient. Whether the management mode change after CAV early prediction reduces the rate of heart transplantation failure, and whether it has wide applicability, it still needs to be confirmed by large-scale clinical trials in the future.Cardiovascular imaging technology has gone through the process from general 2D imaging to 3D stereo imaging, from macroscopic, gross imaging to microscopic, molecular imaging, from simple display to functional information.With the standardization and popularization of applications, its role in the study of disease mechanisms and the optimization of clinical diagnosis and treatment strategies has become increasingly prominent. In addition, intracavitary imaging plays an important role in other cardiovascular fields, such as heart transplantation.Decay and so on.In the future, the continuous advancement of intracavity imaging technology will further promote the development of modern cardiovascular imaging to a higher level.The use of intracavitary imaging to guide clinical treatment will further promote the improvement of cardiovascular disease diagnosis and treatment, and better serve the majority of patients.(7) A promising new field: OCT combined with IVUS.

With the rapid economic development, lifestyle changes and the aging of the population, the proportion of coronary calcification in China is also increasing.Vascular calcification results in increased vascular stiffness, decreased compliance, and increased systolic and pulse pressure.The mechanism of calcification from the occurrence mechanism to the diagnosis and treatment strategy is a major controversial problem in clinical practice, and there is no unified conclusion.In the past, vascular calcification was considered to be a passive, degenerative end-stage process of deposition of calcium salts in the vessel wall dominated by calcium-phosphorus metabolism imbalance.Recent studies have found that vascular calcification is an active, multi-factor involved in the regulation of biological processes, in which inflammation, metabolic disorders, oxidative stress, hormonal interference and chronic stress affect the composition of the vascular microenvironment.This greatly improved the understanding of the mechanism of calcification.So what is the evolution of calcification?The study included 72 baseline and follow-up intra- and extra-segment cross-sectional IVUS-virtual tissue imaging and OCT pairing matching for fusion studies.At the time of follow-up, 46 calcified plaques were detected, 33 in the stent, 13 in the stent, calcification progression (52.2%) or neonatal calcification (47.8%).In October, the volume of calcification increased from baseline to follow-up by 2.3 – 2.4 mm3 (P = 0.001).At baseline virtual histological follow-up, the tissue precursor necrotic nucleus of dense calcium accounted for 73.9%, and fibrous or fibrous fat plaque accounted for 10.9%.Calcification of 15.2% of patients already exists at baseline.71.2% of the calcification precursors on the OCT were lipid pools, 4.3% were fibrous plaques, and 23.9% were fibrous calcified plaques.OCT combined with IVUS in vivo detected a process of calcification evolution, necrosis is the most common calcification precursor, and the stent will lead to a new layer of tissue covering calcification lesions.What is more significant than clinical trials is that OCT combined with IVUS to explore a new field of clinical trials. IVUS has strong penetrating power, can visualize the whole vascular lesions, measure plaque area, plaque load, and show positive remodeling of blood vessels.Negative remodeling is used to quantitatively analyze the effect of a certain treatment on plaque burden. The high resolution of OCT can clearly show lesions or plaques under the intima, identify vulnerable plaques, stabilize plaques, thrombus,Intimal hyperplasia and in-stent restenosis on calcification, dissection, stent and stent surfaces.Therefore, in the future in the vulnerable plaque, interventional therapy, clinical research and evaluation of the efficacy of restenosis, OCT combined with IVUS has important application value.

ouyangshaoxia

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