Relationship of thrombus characteristics to the incidence of angiographically visible distal embolization in patients with ST-segment elevation myocardial infarction treated with thrombus aspiration

Coronary No-Reflow after Primary Percutaneous Coronary Intervention-Current Knowledge on Pathophysiology, Diagnosis, Clinical Impact and Therapy

Coronary no-reflow (CNR) is a frequent phenomenon that develops in patients with ST-segment elevation myocardial infarction (STEMI) following reperfusion therapy. CNR is highly dynamic, develops gradually (over hours) and persists for days to weeks after reperfusion. Microvascular obstruction (MVO) developing as a consequence of myocardial ischemia, distal embolization and reperfusion-related injury is the main pathophysiological mechanism of CNR. The frequency of CNR or MVO after primary PCI differs widely depending on the sensitivity of the tools used for diagnosis and timing of examination. Coronary angiography is readily available and most convenient to diagnose CNR but it is highly conservative and underestimates the true frequency of CNR. Cardiac magnetic resonance (CMR) imaging is the most sensitive method to diagnose MVO and CNR that provides information on the presence, localization and extent of MVO. CMR imaging detects intramyocardial hemorrhage and accurately estimates the infarct size. MVO and CNR markedly negate the benefits of reperfusion therapy and contribute to poor clinical outcomes including adverse remodeling of left ventricle, worsening or new congestive heart failure and reduced survival. Despite extensive research and the use of therapies that target almost all known pathophysiological mechanisms of CNR, no therapy has been found that prevents or reverses CNR and provides consistent clinical benefit in patients with STEMI undergoing reperfusion. Currently, the prevention or alleviation of MVO and CNR remain unmet goals in the therapy of STEMI that continue to be under intense research.

In Vitro Comparison of Several Thrombus Removal Tools

BACKGROUND

Although the routine use of thrombus aspiration is not recommended, the thrombectomy technique still might be considered for a selected population of patients. Therefore, the assessment of the effectiveness of commercially available thrombectomy devices is still clinically relevant.

AIM

Here, we present an in vitro comparison of several different types of catheters that can be used for thrombus aspiration or removal.

METHODS

Through the removal of 6 h and 24 h human blood clots in an in vitro model, four catheters were compared: the Launcher, Pronto V4, Vasco+ and the stent-retriever Catchview. The aspiration efficacy was expressed as a percentage of the initial thrombus weight. The effectiveness of the patient's aspiration was dependent on the time of thrombus formation and was significantly higher for a thrombus formed over 24 h (58.5 ± 26.5%) than for one formed over 6 h (48.0 ± 22.5%; p < 0.001). In the presented in vitro model, Pronto V4 and Launcher showed the highest efficiency.

CONCLUSIONS

Large-bore aspiration catheters were found to be more effective than narrow-bore catheters or stent-retrievers in an in vitro model of thrombus removal. The thrombus aspiration efficacy increases with longer thrombus formation times.

Machine learning assisted reflectance spectral characterisation of coronary thrombi correlates with microvascular injury in patients with ST-segment elevation acute coronary syndrome

Aims

We set out to further develop reflectance spectroscopy for the characterisation and quantification of coronary thrombi. Additionally, we explore the potential of our approach for use as a risk stratification tool by exploring the relation of reflectance spectra to indices of coronary microvascular injury.

Methods and results

We performed hyperspectral imaging of coronary thrombi aspirated from 306 patients presenting with ST-segment elevation acute coronary syndrome (STEACS). Spatially resolved reflected light spectra were analysed using unsupervised machine learning approaches. Invasive [index of coronary microvascular resistance (IMR)] and non-invasive [microvascular obstruction (MVO) at cardiac magnetic resonance imaging] indices of coronary microvascular injury were measured in a sub-cohort of 36 patients. The derived spectral signatures of coronary thrombi were correlated with both invasive and non-invasive indices of coronary microvascular injury. Successful machine-learning-based classification of the various thrombus image components, including differentiation between blood and thrombus, was achieved when classifying the pixel spectra into 11 groups. Fitting of the spectra to basis spectra recorded for separated blood components confirmed excellent correlation with visually inspected thrombi. In the 36 patients who underwent successful thrombectomy, spectral signatures were found to correlate well with the index of microcirculatory resistance and microvascular obstruction; R²: 0.80, p < 0.0001, n = 21 and R²: 0.64, p = 0.02, n = 17, respectively.

Conclusion

Machine learning assisted reflectance spectral analysis can provide a measure of thrombus composition and evaluate coronary microvascular injury in patients with STEACS. Future work will further validate its deployment as a point-of-care diagnostic and risk stratification tool for STEACS care.

Ticagrelor versus clopidogrel in reducing inflammatory cell infiltration of thrombus aspirated in patients with ST-elevation myocardial infarction

BACKGROUND

Ticagrelor provides more rapid, potent, and consistent anti-platelet efficacy than clopidogrel. This randomized trial aimed to evaluate the anti-inflammation effects of ticagrelor versus clopidogrel on thrombus aspirated from the ST-elevation myocardial infarction (STEMI) patients.

METHOD

A total of 98 patients with STEMI and intended percutaneous coronary intervention (PCI) were randomly assigned to receive clopidogrel (600-mg loading dose) or ticagrelor (180-mg loading dose), of whom 55 with large thrombus burden underwent thrombus aspiration during PCI. Thrombus specimens were successfully aspirated from 49 patients. Finally, 24 patients in the clopidogrel group and 23 in the ticagrelor group completed the study. Inflammatory cells within thrombi were assessed by hematoxylin-eosin and immunohistochemistry stainings.

RESULTS

Compared with the clopidogrel group, the number of total inflammatory cells per mm² thrombus area in the ticagrelor group was decreased by 28% (P = 0.009). The numbers of neutrophils and myeloperoxidase-positive cells per mm² thrombus area in the ticagrelor group were respectively decreased by 35% (P = 0.016) and 28% (P = 0.047), as compared with those in the clopidogrel group. Moreover, ticagrelor treatment reduced the ratio of monocytes number higher than 250 per mm² thrombus area compared with clopidogrel treatment (4% versus 29%, P = 0.048).

CONCLUSION

In patients with undergoing PCI for STEMI, the loading dose ticagrelor regimen was associated with a reduction in inflammatory cell infiltration within thrombus compared with the loading dose clopidogrel regimen.

Relationship of superior mesenteric artery thrombus density with transmural intestinal necrosis on multidetector computed tomography in acute mesenteric ischemia

Background

Acute arterial occlusive mesenteric ischemia with transmural intestinal necrosis (TIN) is a fatal disease, which is difficult to diagnose on multidetector computed tomography (MDCT). The aim of the present study was to determine the relationship of superior mesenteric artery (SMA) thrombus density with TIN on MDCT in patients with acute mesenteric ischemia (AMI) due to SMA thromboembolism.

Methods

In this retrospective study, 33 patients who underwent abdominal MDCT and angiography for AMI due to SMA thromboembolism were divided into two groups: the AMI with TIN group and the AMI without TIN group. We analyzed the relationships of clinical characteristics, qualitative MDCT signs, and SMA thrombus density with TIN. The SMA thrombus density was measured on non-contrast MDCT. Univariate and multivariate analyses were performed to determine the risk factors for predicting TIN. The diagnostic performances of risk factors were evaluated by receiver-operating characteristic (ROC) curve analysis.

Results

Of the patients with AMI enrolled in this study, 33.3% (11/33) were diagnosed with TIN. Peritonitis (P=0.042), bowel wall thinning (P=0.033), and pneumatosis/portomesenteric gas (P=0.010) were significantly associated with TIN. AMI patients with TIN exhibited a higher SMA thrombus density than AMI patients without TIN [41.2±6.1 vs. 34.2±3.0 Hounsfield unit (HU), P=0.003]. Multivariate analysis showed that SMA thrombus density was an independent predictor of TIN [P=0.044, hazard ratio (HR): 1.82, 95% confidence interval (CI): 1.02-3.25]. For diagnosing AMI with TIN, the area under the ROC curve (AUC) of SMA thrombus density (0.83) was larger than those of peritonitis (0.68), bowel wall thinning (0.66), and pneumatosis/portomesenteric gas (0.71).

Conclusions

In patients with AMI, erythrocyte-rich thrombus blocking the SMA trunk which has a higher density on MDCT is prone to the occurrence of TIN compared with erythrocyte-scarce thrombus with a lower density. SMA thrombus density could be an independent risk factor for TIN in patients with AMI due to SMA thromboembolism.

Micro-CT-Based Quantification of Extracted Thrombus Burden Characteristics and Association With Angiographic Outcomes in Patients With ST-Elevation Myocardial Infarction: The QUEST-STEMI Study

Background: Angiographic detection of thrombus in STEMI is associated with adverse outcomes. However, routine thrombus aspiration failed to demonstrate the anticipated benefit. Hence, management of high coronary thrombus burden remains challenging. We sought to assess for the first time extracted thrombotic material characteristics utilizing micro-computed tomography (micro-CT). Methods: One hundred thirteen STEMI patients undergoing thrombus aspiration were enrolled. Micro-CT was undertaken to quantify retrieved thrombus volume, surface, and density. Correlation of these indices with angiographic and electrocardiographic outcomes was performed. Results: Mean aspirated thrombus volume, surface, and density (±standard deviation) were 15.71 ± 20.10 mm³, 302.89 ± 692.54 mm², and 3139.04 ± 901.88 Hounsfield units, respectively. Aspirated volume and surface were significantly higher (p < 0.001) in patients with higher angiographic thrombus burden. After multivariable analysis, independent predictors for thrombus volume were reference vessel diameter (RVD) (p = 0.011), right coronary artery (RCA) (p = 0.039), and smoking (p = 0.027), whereas RVD (p = 0.018) and RCA (p = 0.019) were predictive for thrombus surface. Thrombus volume and surface were independently associated with distal embolization (p = 0.007 and p = 0.028, respectively), no-reflow phenomenon (p = 0.002 and p = 0.006, respectively), and angiographically evident residual thrombus (p = 0.007 and p = 0.002, respectively). Higher thrombus density was correlated with worse pre-procedural TIMI flow (p < 0.001). Patients with higher aspirated volume and surface developed less ST resolution (p = 0.042 and p = 0.023, respectively). Conclusions: Angiographic outcomes linked with worse prognosis were more frequent among patients with larger extracted thrombus. Despite retrieving larger thrombus load in these patients, current thrombectomy devices fail to deal with thrombotic material adequately. Further studies of novel thrombus aspiration technologies are warranted to improve patient outcomes. Clinical Trial Registration: QUEST-STEMI trial ClinicalTrials.gov number: NCT03429608 Date of registration: February 12, 2018. The study was prospectively registered.

Different Microcirculation Response Between Culprit and Non-Culprit Vessels in Patients With Acute Coronary Syndrome

Background

This study investigated whether the microvascular dysfunction differed between culprit and non‐culprit vessels in patients with acute coronary syndrome who underwent percutaneous coronary intervention.

Methods and Results

In 115 prospectively recruited patients, after successful percutaneous coronary intervention, culprit and non‐culprit intracoronary hemodynamic measurements were performed and repeated at 6‐month follow‐up. ¹³N‐ammonia positron emission tomography was performed at 6‐month follow‐up visit to determine absolute myocardial blood flow. The resistance values of each vessel were calculated using the coronary pressure data and the myocardial blood flow values obtained from ¹³N‐ammonia positron emission tomography data. We compared the measurements between culprit and non‐culprit vessels and assessed changes in microvascular dysfunction during the study period. In 334 vessels (115 culprit and 219 non‐culprit), the culprit vessel group showed a lower fractional flow reserve and coronary flow reserve than the non‐culprit vessel group at baseline and 6‐month follow‐up, respectively. The value of index of microcirculatory resistance was different between the 2 groups in the baseline but not at 6‐month follow‐up. The microvascular resistance at rest and hyperemic microvascular resistance were not different between the 2 groups, but resistance to stenosis was higher in the culprit vessel group, under both resting and hyperemic status (P=0.02 and P<0.01, respectively). In the culprit vessel analysis, the fractional flow reserve and index of microcirculatory resistance decreased whereas coronary flow reserve increased (P<0.01 for all) at 6‐month follow‐up. However, there was no change in index of microcirculatory resistance, coronary flow reserve, and fractional flow reserve from baseline to 6‐month follow‐up in the non‐culprit vessel analysis.

Conclusions

The observed microvascular dysfunction in acute coronary syndrome is limited to the culprit vessel territory in the acute phase, which is relatively recovered in the chronic phase and there is no out‐of‐culprit territory involvement.

Registration

URL: https://www.clini​caltr​ials.gov; Unique identifier: NCT04169516.

Reflectance spectral analysis for novel characterization and clinical assessment of aspirated coronary thrombi in patients with ST elevation myocardial infarction

OBJECTIVE

The visual appearance of coronary thrombi may be clinically informative in ST elevation myocardial infarction (STEMI) patients undergoing primary percutaneous coronary intervention (pPCI). However, subjective assessment is poorly reproducible and cannot provide an objective basis for treatment decisions or patient stratification. We have assessed the feasibility of a novel reflectance spectroscopy technique to systematically characterize coronary artery thrombi retrieved by aspiration during pPCI in patients with STEMI, and the clinical utility for predicting distal microvascular obstruction.

APPROACH

Patients with STEMI treated with pPCI and thrombus aspiration (n = 288) were recruited from the Oxford Acute Myocardial Infarction (OxAMI) Study. Of these, 158 patients underwent cardiac magnetic resonance imaging within 48 h for assessment of microvascular obstruction (MVO). Coronary thrombi were imaged by reflectance spectroscopy across wavelengths 500-800 nm.

MAIN RESULTS

Spectral data were analysed using function fitting and multivariate models. The coefficient 'c _red' determined from the fitting procedure correlated with the visually-assessed colour of thrombi ('red' or 'white') and with MVO. When applied to a reduced data set, consisting of spectra from 20 patients with the largest MVO and from 20 propensity-score-matched patients with no MVO, three multivariate analysis methods were able to discriminate spectra of thrombi from patients without MVO and with the largest MVO.

SIGNIFICANCE

Reflectance spectral analysis of coronary thrombus provides new insights into the pathology of STEMI, with potential clinical implications for emergency patient care. Further studies are warranted for validation as a point-of-care stratification tool in predicting the degree of microvascular injury and clinical outcomes in STEMI.

Etosis, rather than apoptosis or cell proliferation, typifies thrombus progression - An immunohistochemical study of coronary aspirates

Background

Coronary thrombosis is a process with unpredictable clinical outcome. Changes of thrombus composition overtime influence tissue repair and stabilization. We investigated rates of cell deaths and cell proliferation at different time points after initiation of thrombosis.

Methods

Thrombectomy aspirates of 55 myocardial infarction patients were selected and histomorphologically classified as fresh (25), lytic (25), partially fibrocellular (10), completely fibrocellular (10). Paraffin sections were immunostained with anti-(cleaved) caspase-3/Casp3 (apoptosis), Citrullinated histone/CitH 3 (etosis), C-reactive protein/CRP and Ki67 (proliferation) in combination with either Feulgen counterstaining (DNA) or cell markers for granulocytes, macrophages, SMCs, platelets and endothelium. Rates of apoptosis, etosis and proliferation were measured as a percentage of total number of immunopositive pixels versus total number of DNA positive pixels, while co-localization with cell markers was assessed by digital image analysis.

Results

Positive staining of CitH3 was observed more frequently (93%) than Casp3 (70%), Ki67 (79%) or CRP (59%) (p < 0.05). Moreover, rate of etosis, found in granulocytes and macrophages, differed significantly among thrombi of different age, being higher in lytic (12.82) than in fresh (8.52) and late-organized (2.75) (p < 0.05). Such differences were not observed for the rates of apoptosis or cell proliferation related to thrombus age. CRP staining was present in fresh, lytic and organized thrombi, but did not reliably identify necrotic areas.

Conclusions

Different patterns of cell death and cell proliferation are noticed during progression of coronary thrombus overtime, but with significant differences for only etosis. Etosis could potentially serve as a biomarker for thrombus instability with clinical significance.

Microvascular obstruction in acute myocardial infarction: an old and unsolved mystery

In the setting of acute myocardial infarction, flow restoration in the culprit epicardial coronary artery is not synonymous with efficient reperfusion. Microvascular obstruction occurs in 50% of cases and represents a predictor of a long-term unfavorable outcome. Its prevalence has remained constant in recent years despite various treatment attempts. However, the success of targeted therapies could be mainly a problem of timing. Recent data bring evidence with regard to the role of pre-procedural distal embolization and highlight the relation between distal embolism, microvascular obstruction and intramyocardial inflammation. As a result, early detection of microvascular injury represents the first step in the development of targeted, individualized therapeutic approaches. In this context, the identification of new invasive surrogate parameters for the timely assessment and quantification of microvascular obstruction in the catheterization laboratory has become an important subject of current research. Among these, coronary wedge pressure is the most practical and revealing in the setting of primary percutaneous coronary intervention. It may offer comprehensive details on the mechanisms of microvascular injury and may therefore offer guidance for appropriate treatment selection.

MicroRNA-33 and SIRT1 influence the coronary thrombus burden in hyperglycemic STEMI patients

Primary percutaneous coronary intervention (PPCI) is a pivotal treatment in ST-segment elevation myocardial infarction (STEMI) patients. However, in hyperglycemic-STEMI patients, the incidence of death is still significant. Here, the involvement of sirtuin 1 (SIRT1) and miR33 on the pro-inflammatory/pro-coagulable state of the coronary thrombus was investigated. Moreover, 1-year outcomes in hyperglycemic STEMI in patients subjected to thrombus aspiration before PPCI were evaluated. Results showed that hyperglycemic thrombi displayed higher size and increased miR33, reactive oxygen species, and pro-inflammatory/pro-coagulable markers. Conversely, the hyperglycemic thrombi showed a lower endothelial SIRT1 expression. Moreover, in vitro experiments on endothelial cells showed a causal effect of SIRT1 modulation on the pro-inflammatory/pro-coagulative state via hyperglycemia-induced miR33 expression. Finally, SIRT1 expression negatively correlated with STEMI outcomes. These observations demonstrate the involvement of the miR33/SIRT1 pathway in the increased pro-inflammatory and pro-coagulable state of coronary thrombi in hyperglycemic STEMI patients.

Behçet's syndrome as a tool to dissect the mechanisms of thrombo-inflammation: clinical and pathogenetic aspects

Behçet's syndrome (BS) is a complex disease with different organ involvement. The vascular one is the most intriguing, considering the existence of a specific group of patients suffering from recurrent vascular events involving the venous and, more rarely, the arterial vessels. Several clinical clues suggest the inflammatory nature of thrombosis in BS, especially of the venous involvement, thus BS is considered a model of inflammation-induced thrombosis. Unique among other inflammatory conditions, venous involvement (together with the arterial one) is currently treated with immunosuppressants, rather than with anti-coagulants. Although many in-vitro studies have suggested the different roles of the multiple players involved in clot formation, in-vivo models are crucial to study this process in a physiological context. At present, no clear mechanisms describing the pathophysiology of thrombo-inflammation in BS exist. Recently, we focused our attention on BS patients as a human in-vivo model of inflammation-induced thrombosis to investigate a new mechanism of clot formation. Indeed, fibrinogen displays a critical role not only in inflammatory processes, but also in clot formation, both in the fibrin network and in platelet aggregation. Reactive oxygen species (ROS)-derived modifications represent the main post-translational fibrinogen alterations responsible for structural and functional changes. Recent data have revealed that neutrophils (pivotal in the pathogenetic mechanisms leading to BS damage) promote fibrinogen oxidation and thrombus formation in BS. Altogether, these new findings may help understand the pathogenetic bases of inflammation-induced thrombosis and, more importantly, may suggest potential targets for innovative therapeutic approaches.

Comparison of visual assessment and computer image analysis of intracoronary thrombus type by optical coherence tomography

Background

Analysis of intracoronary thrombus type by optical coherence tomography (OCT) imaging is highly subjective. We aimed to compare a newly developed image analysis method to subjective visual classification of thrombus type identified by OCT.

Methods

Thirty patients with acute ST elevation myocardial infarction were included. Thrombus type visually classified by two independent readers was compared with analysis using QCU-CMS software.

Results

Repeatability of the computer-based measurements was good. By using a ROC, area under curve values for discrimination of white and red thrombi were 0.92 (95% confidence intervals (CI) 0.83–1.00) for median attenuation, 0.96 (95% CI 0.89–1.00) for mean backscatter and 0.96 (95% CI 0.89–1.00) for mean grayscale intensity. Median attenuation of 0.57 mm^-1 (sensitivity 100%, specificity 71%), mean backscatter of 5.35 (sensitivity 92%, specificity 94%) and mean grayscale intensity of 120.1 (sensitivity 85%, specificity 100%) were identified as the best cut-off values to differentiate between red and white thrombi.

Conclusions

Attenuation, backscatter and grayscale intensity of thrombi in OCT images differentiated red and white thrombi with high sensitivity and specificity. Measurement of these continuous parameters can be used as a less user-dependent method to characterize in vivo thrombi. The clinical significance of these findings needs to be tested in further studies.

Phospholipid signaling in innate immune cells

Phospholipids comprise a large body of lipids that define cells and organelles by forming membrane structures. Importantly, their complex metabolism represents a highly controlled cellular signaling network that is essential for mounting an effective innate immune response. Phospholipids in innate cells are subject to dynamic regulation by enzymes, whose activities are highly responsive to activation status. Along with their metabolic products, they regulate multiple aspects of innate immune cell biology, including shape change, aggregation, blood clotting, and degranulation. Phospholipid hydrolysis provides substrates for cell-cell communication, enables regulation of hemostasis, immunity, thrombosis, and vascular inflammation, and is centrally important in cardiovascular disease and associated comorbidities. Phospholipids themselves are also recognized by innate-like T cells, which are considered essential for recognition of infection or cancer, as well as self-antigens. This Review describes the major phospholipid metabolic pathways present in innate immune cells and summarizes the formation and metabolism of phospholipids as well as their emerging roles in cell biology and disease.

Pre-revascularization coronary wedge pressure as marker of adverse long-term left ventricular remodelling in patients with acute ST-segment elevation myocardial infarction

The aim of this study was to investigate the relationship between coronary wedge pressure (CWP), measured as a marker of pre-procedural microvascular obstruction, and left ventricular remodelling in high-risk ST-segment elevation myocardial infarction (STEMI) patients. Pre-revascularization CWP was measured in 25 patients with high-risk anterior STEMI. Left ventricular volumes and ejection fraction were echocardiographically measured at discharge and at follow-up. A 20% increase in left ventricular volumes was used to define remodelling. Patients with CWP ≤ 38 mmHg were characterized by late ventricular remodelling. Patients with CWP > 38 mmHg developed a progressive remodelling process which was associated with a significant 60 months increase in left ventricular volumes (P = 0.01 for end-systolic volume and 0.03 for end-diastolic volume) and a significant decrease in left ventricular ejection fraction (P = 0.05). A significant increase in both left ventricular end-systolic (P = 0.009) and end-diastolic volume (P = 0.02) from baseline to 60 months follow-up was recorded in patients with extracted thrombus length ≥2 mm. Pre-revascularization elevated CWP was associated with increased left ventricular volumes and decreased ejection fraction at long-term follow-up. CWP was a predictor of severe left ventricular enlargement, besides extracted thrombus quantity.

Relationship between thrombus age in aspirated coronary material and mid-term major adverse cardiac and cerebrovascular events in patients with acute myocardial infarction

BACKGROUND AND AIMS

Recent studies have shown that coronary thrombus histopathology is associated with impaired myocardial reperfusion and poor clinical outcome in patients with acute myocardial infarction (AMI). We sought to investigate the age of thrombi aspirated during percutaneous coronary intervention (PCI) in patients with AMI and evaluate the relationship between histopathologic findings and major adverse cardiac and cerebrovascular events (MACCEs) defined as all-cause death, stroke, or myocardial infarction within 6 months of PCI.

METHODS

In this prospective 2-center observational study, coronary material was obtained during PCI from 305 patients with AMI within 24 h of symptom onset. Thrombi were morphologically classified as either only fresh or older (lytic changes or organization).

RESULTS

MACCE occurred in 38 (12.5%) patients. Only fresh thrombi were observed in 114 (37%) of 305 patients; older thrombi were identified in 191 (63%). The rate of MACCE was significantly higher among patients with older thrombus (p = 0.011). Multivariate analysis also showed the presence of older thrombus [odds ratio (OR) 3.03, 95% confidence interval (CI) 1.122-9.522] is an independent predictor of MACCE within 6 months of PCI, as well as age (OR 1.051, 95% CI 1.013-1.094) and creatine kinase concentration (OR 1.025, 95% CI 1.013-1.037). The prevalence of slow flow or distal embolization during PCI and peak creatine kinase concentration were significantly higher in the older thrombus group (p < 0.05, respectively).

CONCLUSIONS

Older thrombus found in aspirated coronary material is associated with impaired myocardial reperfusion and is an independent predictor of mid-term MACCE in patients with AMI.

Molecular signature of coronary stent thrombosis: oxidative stress and innate immunity cells

The clinical impact of in-stent thrombosis is high because it is associated with high mortality and 20 % of the patients suffer a recurrent event within the two following years. The aim of this study was to characterise the morphologic and proteomic profile of in-stent thrombi (IST) in comparison to thrombi developed on native coronary arteries (CT) to identify a differential molecular signature. The study included 45 patients with ST-elevation-myocardial-infarction (STEMI) treated by primary-percutaneous-intervention and thrombus aspiration: 21 had IST and 24 had CT. Thrombi were characterised by morphologic immunohistochemical analysis and differential proteomic profiling (2-DE+MALDI-TOF/TOF). Bioinformatic analysis revealed differences in proteins related to oxidative-stress and cell death/survival. IST showed a higher content of structural proteins (gelsolin, actin-cytoplasmic-1, tropomyosin, and myosin) together with an imbalance in redox-homeostasis related proteins (increased superoxide-dismutase and decreased peroxiredoxin-2 thrombus content), and a coordinated increase of chaperones (HSP60 and HSC70) and cellular quality control-related proteins (26S–protease-regulatory-subunit-7). These changes were reflected into a significant decrease in HSC70 systemic levels and a significant increase in advanced-oxidation-protein-products (AOPP) indicative of increased oxidative stress-mediated protein damage in IST. Our results reveal an imbalance in redox-related proteins indicative of an exacerbated oxidative-stress that leads to an accumulation of AOPP serum levels in IST. Moreover, the coordinated increase in chaperones and regulatory proteins reflects the activation of intracellular protection mechanisms to maintain protein integrity in IST. The failure to counterbalance the stress situation could trigger cellular apoptosis leading to the destabilization of the thrombus and to a worse prognosis of IST-STEMI-patients.

Supplementary Material to this article is available online at www.thrombosis-online.com.

Can thrombectomy and catheters used increase angiographically visible distal embolization in ST elevation myocardial infarction?

INTRODUCTION

Primary percutaneous coronary intervention (PPCI) is the preferred treatment of ST segment elevation myocardial infarction (STEMI). Manual thrombectomy catheters developed to prevent distant embolization are theoretically attractive; however, their clinical efficacy remains controversial. The effects of manual thrombectomy catheters on angiographically visible distal embolisation (AVDE) have not been studied so far. The aim of this study was to evaluate the effects of manual thrombectomy during PPCI on AVDE and to investigate whether there are differences in the incidence of AVDE according to the catheters used.

MATERIAL AND METHODS

Six hundred thirty-six consecutive patients undergoing primary PCI were included in the study between January 2010 and December 2012. Patients were divided into two groups: the PCI only group (465 patients) and the PCI plus manual thrombectomy group (171 patients).

RESULTS

Thrombus aspiration was associated with higher AVDE (13.55% vs. 26.9%, p = 0.0001), lower thrombolysis in myocardial infarction frame rate (2.49 ±0.86 vs. 2.79 ±0.57, p = 0.0001), lower myocardial blush grade (2.31 ±0.87 vs. 2.47 ±0.7, p = 0.016), lower ejection fraction (EF) (49.9 ±8.5 vs. 46.1 ±9.6, p = 0.0001) and higher maximal troponin release (15.7 ±16 vs. 9.4 ±11, p = 0.0001). No difference was observed in terms of mortality between the groups in follow-up (5.2% vs. 9.03%, p = 0.12). Angiographically visible distal embolisation was observed more frequently with Invatec catheters (p = 0.0001).

CONCLUSIONS

Angiographically visible distal embolisation during primary PCI occurs in a significant number of patients treated with manual thrombectomy. The results indicated that the incidence of AVDE may be different depending on the thrombectomy catheters used.

Quantified coronary frequency domain optical coherence tomography signal analysis for the evaluation of erythrocyte-rich thrombus: ex-vivo validation study

Previous study has demonstrated that erythrocyte-rich thrombi contain more inflammatory cells and reflect high thrombus burden, leading to impaired myocardial reperfusion in myocardial infarction. The aim of this study is to investigate the utility of quantified frequency domain optical coherence tomography (FD-OCT) signal analysis in evaluating the erythrocyte-rich thrombus with ex-vivo materials. We evaluated 54 specimens of coronary artery thrombus obtained by thrombectomy catheter from 8 patients who underwent primary percutaneous coronary intervention. The thrombi were immersed in saline immediately after thrombectomy and FD-OCT image acquisition was performed ex-vivo. Quantitative analysis for all contiguous frames was performed by the dedicated automated software (OCT system software, Light Lab Inc.). For the maximum thrombus area, mean signal intensity (MSI) and normalized standard deviation of signal (NSD) was evaluated. All thrombi were stained using double staining of phosphotungstic acid-hematoxylin and eosin to enable automatic extraction of erythrocyte from fibrin. Computer-assisted analysis was performed using dedicated image processing software (WinROOF, Mitani Corp., Tokyo, Japan) for color identification of the erythrocyte area. Erythrocyte-rich thrombus, defined as % erythrocyte [(erythrocyte area/total thrombus area) × 100] ≥ 10%, showed significantly lower MSI [4.39 ± 0.24 vs. 4.74 ± 0.35, p = 0.002] than that of <10%. The cut-off point for prediction of erythrocyte-rich thrombus was defined as MSI ≤ 4.56, sensitivity: 87.5%, specificity: 82.9%, area under the curve: 0.836, respectively). The present ex-vivo study suggested the utility of quantified FD-OCT signal analysis on the detection of erythrocyte-rich thrombus.

Clinic Predictive Factors for Insufficient Myocardial Reperfusion in ST-Segment Elevation Myocardial Infarction Patients Treated with Selective Aspiration Thrombectomy during Primary Percutaneous Coronary Intervention

Background. Insufficient data are available on the potential benefit of selective aspiration and clinical predictors for no-reflow in STEMI patients undergoing primary percutaneous coronary intervention (PPCI) adjunct with aspiration thrombectomy. Objective. The aim of our study was to investigate clinical predictors for insufficient reperfusion in patients with high thrombus burden treated with PPCI and manual aspiration thrombectomy. Methods. From January 2011 till December 2015, 277 STEMI patients undergoing manual aspiration thrombectomy and PPCI were selected and 202 patients with a Thrombolysis in Myocardial Infarction (TIMI) thrombus grade 4~5 were eventually involved in our study. According to a cTFC value, patients were divided into Group I (cTFC > 40), namely, insufficient reperfusion group; Group II (cTFC ≤ 40), namely, sufficient reperfusion group. Results. Univariate analysis showed that hypertension, multivessel disease, time from symptom to PCI (≧4.8 hours), and postaspiration cTFC > 40 were negative predictors for insufficient reperfusion. After multivariate adjustment, age ≧ 60 years, hypertension, time from symptom to PCI (≧4.8 hours), and postaspiration cTFC > 40 were independently associated with insufficient reperfusion in STEMI patients treated with manual aspiration thrombectomy. Upfront intracoronary GP IIb/IIIa inhibitor (Tirofiban) was positively associated with improved myocardial reperfusion. Conclusion. Fully identifying risk factors will help to improve the effectiveness of selective thrombus aspiration.

Thrombus aspirated from patients with ST-elevation myocardial infarction: Clinical and angiographic outcomes

Objective

To investigate differences in clinical and angiographic outcomes between patients with acute myocardial infarction with red and white thrombi.

Methods

A total of 137 patients with ST-segment elevation myocardial infarction undergoing primary percutaneous coronary interventions were included. Thrombus material was classified as white or red based on its pathology. Information on characteristics of thrombi was available for 97 (70.8%) patients.

Results

The total ischaemic time was significantly longer in the red thrombus group compared with the white thrombus group. The incidence of major adverse cardiovascular events in hospital was higher in the red thrombus group than in the white thrombus group (15.6% vs 0%). Multivariable logistic analysis showed that the total ischaemic time was the only predictor of thrombus composition (odds ratio 1.353; 95% confidence interval 1.003, 1.826).

Conclusion

Red thrombi were present in nearly two-thirds of cases, and were associated with a longer ischaemic time and higher incidence of major adverse cardiovascular events in hospital.

Development and Validation of a Distal Embolization Risk Score During Primary Angioplasty in ST-Elevation Myocardial Infarction

This study aims to develop and validate a new angiographic risk score to predict the risk of distal embolization (DE) during primary percutaneous coronary intervention (p-PCI) for ST-elevation myocardial infarction. Study included data from 1,200 patients who underwent p-PCI. The cohort was randomly split into a derivation cohort (n = 814) and a validation cohort (n = 386). Logistic regression was used to examine the relation between risk factors and the occurrence of DE. To each covariate in the model was assigned an integer score based on the regression coefficients. Variables included in the risk score, according to multivariable analysis, were occlusion pattern of infarct-related artery, Thrombolysis In Myocardial Infarction Thrombus Score 2 to 4, reference vessel diameter ≥3.5 mm, and lesion length >20 mm. To each variable was assigned a 0- to +2-point score according to the strength of the statistical association. Rates of DE in low-, intermediate-, and high-risk groups were 5.6%, 15.8%, and 40% in the derivation cohort (p for trend <0.0001; C-statistic 0.70) and 7.5%, 12.1%, and 37.9% in the validation cohort (p for trend <0.0001; C-statistic 0.62), respectively. In conclusion, the individual risk of DE in patients who underwent p-PCI can be predicted using a simple 4-variables model based on angiographic features.

Clinical significance of no-reflow in different stages of primary angioplasty among patients with acute myocardial infarctions

Background:

The coronary no-reflow (NR) phenomenon, which is associated with poor clinical outcomes, is usually referred to as a post-percutaneous coronary intervention (PCI) state. NR can occur in different stages of the PCI procedure, not only including the post-stenting stage, but from balloon pre-dilation to pre-stenting. The clinical significance of NR in the different stages of the PCI procedure is unclear. The purpose of the current study was to analyze the clinical and angiographic characteristics, the prognosis for NR patients in the aforementioned two stages and to determine the predictors of NR in the early stage.

Methods:

Between January 2009 and December 2013, a total of 420 consecutive patients with ST-segment elevation myocardial infarction (STEMI) underwent primary PCI. Sixty-three patients (15%) with NR constituted the study population. The patients were divided into an early NR group and a subsequent NR group. The clinical and angiographic findings were compared between the two groups. Multivariate logistic regression was used to determine the predictors for early NR. The long-term clinical outcomes after PCI were analyzed.

Results:

Regarding the baseline characteristics, we identified that the early NR group had statistically significant effects on the higher percentage of diabetes mellitus (42.9% vs. 20%), lower admission systolic blood pressure (SBP) (102.2±8.3 mmHg vs. 110.5±7.6 mmHg), higher percentage of Killip classification III (71.4% vs. 45.7%,) and longer reperfusion time (7.1±2.3 h vs. 5.88±2.2 h) compared to the subsequent NR group. There were significant differences between the two groups with respect to the percentage of initial thrombolysis in myocardial infarction (TIMI) flow 0/1 (64.3% vs. 37.1%), target lesion length (31.4±13.6 mm vs. 20.5±17.3 mm) and thrombus score ⩾4 (67.9% vs. 42.9%; p<0.05 for all). Multiple stepwise logistic regression analysis indicated that an admission SBP <100 mmHg (OR=4.580; 95% CI=1.385–15.150; p=0.0130), reperfusion time ⩾6 h (OR=4.978; 95% CI=1.468–16.882; p=0.010) and a thrombus score ⩾4 (OR=2.708; 95% CI=0.833–8.799; p=0.008) were the independent determinants of the early NR. During a 1-year follow-up, the all-cause mortality and overall major adverse cardiac events (MACEs) in the early NR group occurred significantly more often than in the subsequent NR group (28.6% vs. 5.7% and 35.7% vs. 14.3%, respectively, p <0.05). The early NR group had a lower left ventricular ejection fraction (LVEF) (42.5±4.7 vs. 47.8±3.5, p <0.001) and a larger left ventricular end diastolic diameter (LVEDD) (56.0±4.0 vs. 51.5 ±4.7, p=0.001) at the end of the follow-up.

Conclusion:

Early NR patients during primary PCI have more severe baseline clinical and angiographic characteristics, as well as a poorer long-term prognosis.

Coronary thrombus in patients undergoing primary PCI for STEMI: Prognostic significance and management

Acute ST-elevation myocardial infarction (STEMI) usually results from coronary atherosclerotic plaque disruption with superimposed thrombus formation. Detection of coronary thrombi is a poor prognostic indicator, which is mostly proportional to their size and composition. Particularly, intracoronary thrombi impair both epicardial blood flow and myocardial perfusion, by occluding major coronary arteries and causing distal embolization, respectively. Thus, although primary percutaneous coronary intervention is the preferred treatement strategy in STEMI setting, the associated use of adjunctive antithrombotic drugs and/or percutaneous thrombectomy is crucial to optimize therapy of STEMI patients, by improving either angiographical and clinical outcomes. This review article will focus on the prognostic significance of intracoronary thrombi and on current antithrombotic pharmacological and interventional strategies used in the setting of STEMI to manage thrombotic lesions.

Thrombus burden and myocardial damage during primary percutaneous coronary intervention

Large thrombus burden (LTB) lesions in the context of primary percutaneous coronary intervention (p-PCI) have been related to unsuccessful angiographic reperfusion and unfavorable clinical outcomes. However, the hazard of LTB treatment on myocardial damage has not been evaluated. We investigated the impact of LTB on myocardial damage using contrast-enhanced cardiac magnetic resonance (CE-CMR) in the setting of p-PCI. In 327 patients, who underwent p-PCI without thrombus aspiration within 12 hours from symptom onset, we prospectively assessed the impact of LTB on infarct size and microvascular damage using CE-CMR. LTB was defined by the presence of Thrombolysis In Myocardial Infarction thrombus score ≥3 in patent infarct-related artery (IRA); or by "cut-off" occlusion pattern and/or large reference vessel diameter (≥3.5 mm) in occluded IRA. One hundred ninety-seven patients (60.2%) showed LTB and 130 (39.8%) did not. Distal embolization occurred in 18.8% patients with versus 6.9% without LTB (p = 0.003). At CE-CMR, patients with LTB had larger infarct size index (27.5 ± 11.1 vs 22.1 ± 17.5, p = 0.009) and more often transmural necrosis (70.5% vs 55.4%, p = 0.008) compared with patients without LTB. Excluding patients with distal embolization, patients with LTB still had larger necrosis. At multivariate analysis, occluded (IRA) at baseline, anterior infarction, and presence of LTB predicted transmural necrosis. In conclusion, LTB in the setting of p-PCI is related to larger myocardial damage as detected by CE-CMR, regardless of angiographic detectable distal embolization.

Usefulness of local delivery of thrombolytics before thrombectomy in patients with ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention (the delivery of thrombolytics before thrombectomy in patients with ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention [DISSOLUTION] randomized trial)

Thrombus aspiration during percutaneous coronary intervention can result in improved rates of normal epicardial flow and myocardial perfusion, but several unmet needs remain. The purpose of the Delivery of thrombolytIcs before thrombectomy in patientS with ST-segment elevatiOn myocardiaL infarction Undergoing primary percuTaneous coronary interventION (DISSOLUTION) trial was to evaluate the hypothesis that local delivery of thrombolytics can enhance the efficacy of thrombus aspiration in patients with ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention. A total of 102 patients with ST-segment elevation myocardial infarction and angiographic evidence of massive thrombosis in the culprit artery were randomly assigned to receive a local, intrathrombus bolus of 200,000 U of urokinase (n = 51) or saline solution (n = 51) by way of an infusion microcatheter, followed by manual aspiration thrombectomy. The end points included the final Thrombolysis In Myocardial Infarction flow grade and frame count, myocardial blush grade, 60-minute ST-segment resolution >70%, and major adverse cardiac and cerebrovascular events, defined as the death, reinfarction, stroke, or clinically driven target vessel revascularization at 6 months. The use of intrathrombus urokinase was associated with a significantly higher incidence of Thrombolysis In Myocardial Infarction flow grade 3 (90% vs 66%, p = 0.008) and lower postpercutaneous coronary intervention Thrombolysis In Myocardial Infarction frame count (19 ± 15 vs 25 ± 17, p = 0.033). The postprocedural myocardial perfusion was significantly increased with the use of urokinase (myocardial blush grade 2 or 3, 68% vs 45%, p = 0.028), with more patients showing ST-segment resolution >70% (82% vs 55%, p = 0.006). At 6 months of follow-up, the patients treated with intrathrombus urokinase showed a better major adverse cardiac event-free survival (6% vs 21%; log-rank p = 0.044). In conclusion, local, intrathrombus delivery of thrombolytics before manual thrombectomy improved the postprocedural coronary flow and myocardial perfusion and the 6-month clinical outcomes.