Advances and Challenges in Biomarkers Use for Coronary Microvascular Dysfunction: From Bench to Clinical Practice.

Coronary microvascular dysfunction (CMD) is related to a broad variety of clinical scenarios in which cardiac microvasculature is morphologically and functionally affected, and it is associated with impaired responses to vasoactive stimuli. Although the prevalence of CMD involves about half of all patients with chronic coronary syndromes and more than 20% of those with acute coronary syndrome, the diagnosis of CMD is often missed, leading to the underestimation of its clinical importance. The established and validated techniques for the measurement of coronary microvascular function are invasive and expensive. An ideal method to assess endothelial dysfunction should be accurate, non-invasive, cost-effective and accessible. There are varieties of biomarkers available, potentially involved in microvascular disease, but none have been extensively validated in this heterogeneous clinical population. The investigation of potential biomarkers linked to microvascular dysfunction might improve the assessment of the diagnosis, risk stratification, disease progression and therapy response. This review article offers an update about traditional and novel potential biomarkers linked to CMD.

Novel Biomarkers in Heart Failure: New Insight in Pathophysiology and Clinical Perspective.

Heart failure (HF) is a complex clinical syndrome with a huge social burden in terms of cost, morbidity, and mortality. Brain natriuretic peptide (BNP) appears to be the gold standard in supporting the daily clinical management of patients with HF. Novel biomarkers may supplement BNP to improve the understanding of this complex disease process and, possibly, to personalize care for the different phenotypes, in order to ameliorate prognosis. In this review, we will examine some of the most promising novel biomarkers in HF. Inflammation plays a pivotal role in the genesis and progression of HF and, therefore, several candidate molecules have been investigated in recent years for diagnosis, prognosis, and therapy monitoring. Noncoding RNAs are attractive as biomarkers and their potential clinical applications may be feasible in the era of personalized medicine. Given the complex pathophysiology of HF, it is reasonable to expect that the future of biomarkers lies in the application of precision medicine, through wider testing panels and "omics" technologies, to further improve HF care delivery.

Prevalence and characteristics of myocardial injury during COVID-19 pandemic: A new role for high-sensitive troponin.

BACKGROUND: Coronavirus disease 2019 (COVID-19) is a pandemic disease that is causing a public health emergency. Characteristics and clinical significance of myocardial injury remain unclear. METHODS: This retrospective single-center study analyzed 189 patients who received a COVID-19 diagnosis out of all 758 subjects with a high sensitive troponin I (Hs-TnI) measurement within the first 24 h of admission at the Policlinico A.Gemelli (Rome, Italy) between February 20th 2020 to April 09th 2020. RESULTS: The prevalence of myocardial injury in our COVID-19 population is of 16%. The patients with cardiac injury were older, had a greater number of cardiovascular comorbidities and higher values of acute phase and inflammatory markers and leucocytes. They required more frequently hospitalization in Intensive Care Unit (10 [32.3%] vs 18 [11.4%]; p = .003) and the mortality rate was significantly higher (17 [54.8%] vs. 15 [9.5%], p < .001). Among patients in ICU, the subjects with myocardial injury showed an increase need of endotracheal intubation (8 out of 9 [88%] vs 7 out of 19[37%], p = .042). Multivariate analyses showed that hs-TnI can significantly predict the degree of COVID-19 disease, the intubation need and in-hospital mortality. CONCLUSIONS: In this study we demonstrate that hs-Tn can significantly predict disease severity, intubation need and in-hospital death. Therefore, it may be reasonable to use Hs-Tn as a clinical tool in COVID-19 patients in order to triage them into different risk groups and can play a pivotal role in the detection of subjects at high risk of cardiac impairment during both the early and recovery stage.

Healed Plaques in Patients With Stable Angina Pectoris.

OBJECTIVE: Healed plaques, signs of previous plaque destabilization, are frequently found in the coronary arteries. Healed plaques can now be diagnosed in living patients. We investigated the prevalence, angiographic, and optical coherence tomography features of healed plaques in patients with stable angina pectoris. Approach and Results: Patients with stable angina pectoris who had undergone optical coherence tomography imaging were included. Healed plaques were defined as plaques with one or more signal-rich layers of different optical density. Patients were divided into 2 groups based on layered or nonlayered phenotype at the culprit lesion. Among 163 patients, 87 (53.4%) had layered culprit plaque. Patients with layered culprit plaque had more multivessel disease (62.1% versus 44.7%, P=0.027) and more angiographically complex culprit lesions (64.4% versus 35.5%, P<0.001). Layered culprit plaques had higher prevalence of lipid plaque (83.9% versus 64.5%, P=0.004), macrophage infiltration (58.6% versus 35.5%, P=0.003), calcifications (78.2% versus 63.2%, P=0.035), and thrombus (28.7% versus 14.5%, P=0.029). Lipid index (P=0.001) and percent area stenosis (P=0.015) were greater in the layered group. The number of nonculprit plaques, evaluated using coronary angiograms, tended to be greater in patients with layered culprit plaque (4.2±2.5 versus 3.5±2.1, P=0.053). Nonculprit plaques in patients with layered culprit lesion had higher prevalence of layered pattern (P=0.002) and lipid phenotype (P=0.005). Lipid index (P=0.013) and percent area stenosis (P=0.002) were also greater in this group. CONCLUSIONS: In patients with stable angina pectoris, healed culprit plaques are common and have more features of vulnerability and advanced atherosclerosis both at culprit and nonculprit lesions.

Correlation between CD4+CD28null T lymphocytes, regulatory T cells and plaque rupture: An Optical Coherence Tomography study in Acute Coronary Syndromes.

BACKGROUND: A sizeable proportion of patients with Acute Coronary Syndromes (ACS) shows a unique adaptive immune system profile, associated to a worse outcome, characterized by higher CD4+CD28null T-cells, lower regulatory T-cells (Treg) and increased CD4+CD28null/Treg ratio. We sought to investigate the correlation between CD4+CD28null T-cells, Treg, CD4+CD28null/Treg ratio and plaque phenotype as assessed by Optical Coherence Tomography (OCT). METHODS: Peripheral blood mononuclear cells (PBMC) were collected from 30 Non-ST Elevation Myocardial Infarction (NSTEMI) patients, sub-grouped according to OCT analysis of culprit lesions into two cohorts: Ruptured Fibrous Cap (NSTEMI-RFC, n = 12) and Intact Fibrous Cap (NSTEMI-IFC, n = 18). Stable Angina patients (SA, n = 18) were used as controls. We examined the frequency of CD4+CD28null and Treg (defined as CD4+CD25highCD127lowFoxp3+ T-cells) by flow-cytometry. RESULTS: CD4+CD28null frequency (median, range) was significantly higher in NSTEMI-RFC patients (17.3%, 12.5-33.8) as compared with NSTEMI-IFC (3.8%, 0.3-14.1) and SA (3%, 0.6-17.7) (P < 0.001 for all comparisons). We also found a higher CD4+CD28null/Treg ratio in NSTEMI-RFC patients (6.6%, 3.7-13.9) than in NSTEMI-IFC (1.6%, 0.3-5.2) and SA (1.2%, 0.3-8.7) (P < 0.001 for all comparisons). Finally, there was an inverse correlation between CD4+CD28null/Treg ratio and cap-thickness (R = -0.44; P = 0.002). CONCLUSION: Patients with NSTEMI presenting with RFC as culprit lesion at OCT evaluation have a specific perturbation of adaptive immunity, mostly involving CD4+CD28null T- cells and Tregs, as compared with patients with IFC and SA. This specific imbalance of T-cells might play a key role in fibrous cap thinning, predisposing atherosclerotic plaque to rupture.

Inflammasome, T Lymphocytes and Innate-Adaptive Immunity Crosstalk: Role in Cardiovascular Disease and Therapeutic Perspectives.

Over the past few decades, lot of evidences have shown atherosclerosis as a chronic progressive disease with an exquisite inflammatory feature. More recently, the role of innate immune response in the onset and progression of coronary artery disease (CAD) and an adaptive immunity imbalance, mostly involving T cell sub-sets, have been documented. Therefore, like in many other inflammatory and autoimmune disorders, an altered innate-adaptive immunity crosstalk could represent the key of the inflammatory burden leading to atherosclerotic plaque formation and progression and to the breakdown of plaque stability. In this review, we will address the role of inflammasome in innate immunity and in the imbalance of adaptive immunity. We will discuss how this altered immune crosstalk is related to CAD onset and progression. We will also discuss how unravelling the key molecular mechanisms is of paramount importance in the development of therapeutic tools to delay the chronic progression and prevent the acute destabilization of atherosclerotic plaque.

Indoleamine 2,3-Dioxygenase (IDO) Enzyme Links Innate Immunity and Altered T-Cell Differentiation in Non-ST Segment Elevation Acute Coronary Syndrome.

Atherosclerosis is a chronic inflammatory disease characterized by a complex interplay between innate and adaptive immunity. Dendritic cells (DCs) play a key role in T-cell activation and regulation by promoting a tolerogenic environment through the expression of the immunosuppressive enzyme indoleamine 2,3-dioxygenase (IDO), an intracellular enzyme involved in tryptophan catabolism. IDO expression and activity was analyzed in monocytes derived DCs (MDDCs) from non-ST segment elevation myocardial infarction (NSTEMI) patients, stable angina (SA) patients and healthy controls (HC) by real-time quantitative polymerase chain reaction (RT-qPCR) before and after in vitro maturation with lipopolysaccharide (LPS). The amount of tryptophan catabolite; kynurenine; was evaluated in the culture supernatants of mature-MDDCs by ELISA assay. Autologous mixed lymphocyte reaction (MLR) between mature-MDDCs and naïve T-cells was carried out to study the differentiation towards T-helper 1 (Th1) and induced regulatory T-cells (iTreg). Analysis of IDO mRNA transcripts in mature-MDDCs revealed a significant reduction in cells isolated from NSTEMI (625.0 ± 128.2; mean ± SEM) as compared with those from SA (958.5 ± 218.3; p = 0.041) and from HC (1183.6 ± 231.6; p = 0.034). Furthermore; the concentration of kynurenine was lower in NSTEMI patients (2.78 ± 0.2) and SA (2.98 ± 0.25) as compared with HC (5.1 ± 0.69 ng/mL; p = 0.002 and p = 0.016; respectively). When IDO-competent mature-MDDCs were co-cultured with allogeneic naïve T-cells, the ratio between the percentage of generated Th1 and iTreg was higher in NSTEMI (4.4 ± 2.9) than in SA (1.8 ± 0.6; p = 0.056) and HC (0.9 ± 0.3; p = 0.008). In NSTEMI, the tolerogenic mechanism of the immune response related to IDO production by activated MDDCs is altered, supporting their role in T-cell dysregulation.

Atorvastatin inhibits the immediate-early response gene EGR1 and improves the functional profile of CD4+T-lymphocytes in acute coronary syndromes.

Background- Adaptive immune-response is associated with a worse outcome in acute coronary syndromes. Statins have anti-inflammatory activity beyond lowering lipid levels. We investigated the effects of ex-vivo and in-vivo atorvastatin treatment in acute coronary syndromes on CD4+T-cells, and the underlying molecular mechanisms.Approach and results- Blood samples were collected from 50 statin-naïve acute coronary syndrome patients. We assessed CD4+T-cell activation by flow-cytometry, the expression of 84 T-helper transcription-factors and 84 T-cell related genes by RT-qPCR, and protein expression by Western-blot, before and after 24-hours incubation with increasing doses of atorvastatin: 3-10-26 µg/ml (corresponding to blood levels achieved with doses of 10-40-80 mg, respectively). After incubation, we found a significant decrease in interferon-γ-producing CD4+CD28nullT-cells (P = 0.009) and a significant increase in interleukin-10-producing CD4+CD25highT-cells (P < 0.001). Atorvastatin increased the expression of 2 genes and decreased the expression of 12 genes (in particular, EGR1, FOS,CCR2 and toll like receptor-4; >3-fold changes).The in-vivo effects of atorvastatin were analyzed in 10 statin-free acute coronary syndrome patients at baseline, and after 24h and 48h of atorvastatin therapy (80 mg/daily): EGR1-gene expression decreased at 24h (P = 0.01) and 48h (P = 0.005); EGR1-protein levels decreased at 48h (P = 0.03).Conclusions-In acute coronary syndromes, the effects of atorvastatin on immune system might be partially related to the inhibition of the master regulator gene EGR1. Our finding might offer a causal explanation on why statins improve the early outcome in acute coronary syndromes.

Bivalirudin versus unfractionated heparin for residual thrombus burden: a frequency-domain optical coherence tomography study.

OBJECTIVES: This study aimed to compare the effect of bivalirudin and unfractionated heparin (UFH) on residual thrombus burden assessed by frequency-domain optical coherence tomography (FD-OCT), and on angiographic indices of microvascular obstruction (MVO). BACKGROUND: The efficacy of bivalirudin to inhibit thrombus formation inside the stent during percutaneous coronary interventions (PCI) as compared to UFH is unknown. METHODS: Sixty patients with coronary artery disease who underwent post-PCI FD-OCT were studied, including 20 patients treated with bivalirudin and 40 control patients treated with UFH, matched by clinical presentation, stent characteristics, and periprocedural medications. In-stent thrombus volume, thrombus score (number of quadrants with thrombus), and thrombus type (white/red) were assessed by FD-OCT. Thrombolysis in myocardial infarction (TIMI) flow grade, corrected TIMI frame count (cTFC), and Quantitative Blush Evaluator (QuBE) score were recorded. RESULTS: Patients treated with bivalirudin showed similar thrombus volume (0.14 mm(3) [0.00-0.88] vs. 0.13 mm(3) [0.00-0.63], P = 0.962), thrombus score (10 [0-25] vs. 8 [0-21], P = 0.849) and thrombus length (1.70 mm [0.00-4.10] vs. 1.40 mm [0.00-4.05], P = 0.968], as compared with patients treated with UFH. Patients in the bivalirudin group showed lower proportion of white thrombus (55.5% vs. 78.6%, P = 0.016). There was no significant difference in TIMI flow grade, cTFC, and QuBE score between the two groups. CONCLUSIONS: The present study showed similar residual thrombus burden and angiographic indices of MVO immediately after PCI between patients treated with bivalirudin and those treated with UFH.

Platelet function and long-term antiplatelet therapy in women: is there a gender-specificity? A 'state-of-the-art' paper.

Although the female gender is generally less represented in cardiovascular studies, observational and randomized investigations suggest that-compared with men-women may obtain different benefits from antiplatelet therapy. Multiple factors, including hormonal mechanisms and differences in platelet biology, might contribute to such apparent gender peculiarities. The thrombotic and bleeding risks, as well as outcomes after a cardiovascular event, appear to differ between genders, partly in relation to differences in age, comorbidities and body size. Equally, the benefits of antiplatelet therapy may differ in women compared with men in different vascular beds, during primary or secondary prevention and according to the type of an antiplatelet agent used. This document is an attempt to bring together current evidence, clinical practices and gaps of knowledge on gender-specific platelet function and antiplatelet therapy. On the basis of the available data, we provide suggestions on current indications of antiplatelet therapy for cardiovascular prevention in women with different clinical features; no strong recommendation may be given because the available data derive from observational studies or post hoc/subgroup analyses of randomized studies without systematic adjustments for baseline risk profiles.

Endothelial progenitor cells in morbid obesity.

BACKGROUND: The aim of this study was to assess the relationship among anthropometric indexes of adiposity (body mass index [BMI], waist circumference [WC]), endothelial progenitor cells (EPC) and carotid intima-media thickness (IMT) in patients with morbid obesity, and the effect of diabetes and weight loss. METHODS AND RESULTS: BMI, WC, IMT and circulating EPC (defined as CD34+/KDR+/CD45- cells) were assessed in 100 patients (37 with diabetes). Fifty patients underwent bariatric surgery, and in 48 of them a complete re-assessment after an average follow-up of 252±108 days was carried out. In 29 of them subcutaneous and visceral adipose tissue samples were obtained at the time of intervention and analyzed for the presence and number of EPC. EPC were directly correlated with weight, BMI, WC and insulin level, and inversely with mean IMT. All correlations were confined to non-diabetic patients. EPC were found in both subcutaneous and visceral adipose tissue specimens. Circulating EPC significantly decreased after weight loss (P=0.002). CONCLUSIONS: EPC are positively related to markers of adiposity in severe obesity, when not complicated by diabetes. Weight loss is associated with decrease in EPC level. EPC are inversely correlated with IMT, confirming their protective role also in severe obesity. Diabetes has a negative modulating action.

Predictors of postoperative atrial fibrillation in patients with coronary artery disease undergoing cardiopulmonary bypass: a possible role for myocardial ischemia and atrial inflammation.

OBJECTIVE: To evaluate the preoperative presence of C-reactive protein (CRP) and troponin T(hs-TnT) in patients with coronary artery disease (CAD) undergoing cardiopulmonary bypass (CPB) in order to better clarify the role of atrial inflammation and/or myocardial ischemia in the development of postoperative atrial fibrillation (POAF). DESIGN: Prospective, nonrandomized study. SETTING: University hospital. PARTICIPANTS: Thirty-eight consecutive ischemic patients admitted to the authors' hospital for CAD undergoing elective on-pump coronary artery bypass grafting (CABG). INTERVENTION: Elective on-pump CABG. MEASUREMENTS AND MAIN RESULTS: Peripheral blood samples were collected from all patients before and 24 hours after CABG to assess high sensitive (hs)-CRP and troponin T (hs-TnT) levels. The patients' heart rhythm was monitored by continuous ECG telemetry. Biopsies from the right atrial appendage were obtained at the beginning of the CABG procedure in order to perform immunohistochemistry for CRP and reverse transcription polymerase chain reaction for CRP mRNA expression. Fourteen patients out of 38 (36%) developed POAF. Atrial CRP was found in 31 patients (82%), 10 with POAF and 21 with sinus rhythm (71% v 87% respectively, p = ns). None of the atrial samples was positive for CRP mRNA. Atrial CRP did not correlate with serum hs-CRP levels and with occurrence of POAF, but with the incidence of diabetes (p = 0.010). Postoperative hs-TnT levels, but not hs-CRP levels, were identified as the only predictor of POAF occurrence (p = 0.016). CONCLUSIONS: In patients undergoing CABG, neither peripheral nor tissue preoperative CRP levels, but only postoperative hs-TnT levels, correlated with POAF, suggesting the primary role of an ischemic trigger of atrial fibrillation.

Endothelial progenitor cells, microvascular obstruction, and left ventricular remodeling in patients with ST elevation myocardial infarction undergoing primary percutaneous coronary intervention.

Endothelial progenitor cells (EPCs) are released from the bone marrow during cardiac ischemic events, potentially influencing vascular and myocardial repair. We assessed the clinical and angiographic correlates of EPC mobilization at the time of primary percutaneous coronary intervention in 78 patients with ST elevation myocardial infarction and the impact of both baseline and follow-up EPC levels on left ventricular (LV) remodeling. Blood samples were drawn from the aorta and the culprit coronary artery for cytofluorimetric EPC detection (CD34+CD45dimKDR+ cells, in percentage of cytofluorimetric counts). Area at risk was assessed by Bypass Angioplasty Revascularization Investigation myocardial jeopardy index, thrombotic burden as thrombus score and microvascular obstruction (MVO) as a combination of ST segment resolution and myocardial blush grade. Echocardiographic evaluation of LV remodeling was performed at 1-year follow-up in 54 patients, whereas peripheral EPC levels were reassessed in 40 patients. EPC levels during primary percutaneous coronary intervention were significantly higher in intracoronary than in aortic blood (0.043% vs 0.0006%, p <0.001). Both intracoronary and aortic EPC were related to area at risk extent, to intracoronary thrombus score (p <0.001), and inversely to MVO (p = 0.001). Peripheral EPC levels at 1-year follow-up were lower in patients with LV remodeling than in those without (0.001% [0.001 to 0.002] vs 0.003% [0.002 to 0.010]; p = 0.01) and independently predicted absence of remodeling at multivariate analysis. In conclusion, a rapid intracoronary EPC recruitment takes place in the early phases of ST elevation myocardial infarction, possibly reflecting an attempted reparative response. The extent of this mobilization seems to be correlated to the area at risk and to the amount of MVO. Persistently low levels of EPC are associated to LV remodeling.

Microparticles and microRNAs: new players in the complex field of coagulation.

Atherosclerosis is a complex process that begins with endothelial dysfunction, and continues with several inflammatory processes leading, eventually, to plaque rupture and formation of arterial thrombus. Increased platelet reactivity and classical coagulation pathways are not the only players of the whole thrombotic process: microparticles (MPs), irregularly shaped small vesicles released from the plasma membrane after cell activation, apoptosis, or exposure to shear stress have been demonstrated to be involved in such a process. MicroRNAs (MiRs), small-non-coding single-strand RNAs acting as post-transcriptional modulator of target gene expression are expressed in the large majority of eukaryotes. MiRs are implicated in several phenomena: control of metabolism, control of cell-differentiation, control of cell-proliferation and control of cell-apoptosis, therefore contributing to physiologic and pathogenic processes in hematologic, genetic, infective and cardiac diseases. Microparticles operate as a delivery system of MiRs, playing an active and important role in processes such as coagulation and thrombosis. These novel findings also suggest MPs and, in particular MIRs, as possible and promising therapeutic targets.

Differences in microparticle release in patients with acute coronary syndrome and stable angina.

BACKGROUND: Microparticles (MP) are vesicles released from activated or apoptotic cells. Endothelial MP (EMP) are derived from injured endothelium, platelet MP (PMP) from activated platelets, and Annexin V positive MP (AMP) from apoptotic endothelial cells. The aim was to assess the release of MP and its association with inflammation and atherosclerotic burden. METHODS AND RESULTS: AMP, EMP and PMP were measured on admission (Day 0) in 33 patients with stable angina (SA) and 43 patients with acute coronary syndrome (ACS) undergoing percutaneous coronary interventions (PCI). In SA, peripheral artery disease (PAD) was assessed by ultrasound examination. In 30 of the 76 patients (20 ACS and 10 SA), MP, high-sensitivity-C-reactive protein (hs-CRP), and troponin T (TnT) levels were also assessed 24h (Day 1) and 48 h (Day 2) after PCI. AMP, EMP, and PMP were higher in ACS than in SA (all P<0.01). In the SA group, AMP, PMP, and EMP were similar in patients with or without PAD. In the ACS group, AMP increased until Day 2 (P=0.001), while EMP and PMP peaked on Day 1 (P<0.01) then decreased to baseline values. Day 2 AMP correlated with Day 2 TnT levels (r=0.43, P=0.01) while Day 1 EMP and PMP correlated with Day 1 hs-CRP (r=0.37, P=0.04 and r=0.33, P=0.05; respectively). CONCLUSIONS: Higher MP levels were observed in ACS than in SA. Atherosclerotic burden did not affect MP levels in stable patients.

Predictors of thromboxane levels in patients with non-ST-elevation acute coronary syndromes on chronic aspirin therapy.

High levels of thromboxane A2 (TxA2), a key mediator of platelet activation and aggregation, are associated with an increased risk of cardiovascular events. We aimed at assessing the predictors of higher plasma levels of TxB2, the stable metabolite of TxA2, in consecutive patients presenting with non-ST-elevation acute coronary syndrome (NSTE-ACS) on previous aspirin (ASA) treatment undergoing coronary angiography. Ninety-eight consecutive patients (age 61 ± 11, 75% males) with NSTE-ACS, on previous chronic ASA treatment, were prospectively enrolled in this study. Coronary disease extent was assessed by angiography according to the Bogaty score. In all patients, admission plasma levels of TxB2 (pg/ml) were measured by enzyme-linked immunosorbent assay, and patients showing TxB2 levels in the fourth quartile were compared to patients showing TxB2 levels in the lower quartiles. Multivariable logistic regression analysis showed that platelet count (odds ratio [OR] 1.18, 95% confidence interval [CI] 1.02-1.63, p=0.04), multivessel coronary disease (OR 1.37, 95% CI 1.13-3.67, p=0.03), and coronary atherosclerosis extent index (OR 1.91, 95% CI 1.45-6.79, p=0.001) were independent predictors of TxB2 level upper quartile. Of note, C-reactive protein serum levels were similar in patients with TxB2 levels in the upper quartile as compared to those in the lower quartiles (p=0.49). In conclusion, NSTE-ACS patients with severe coronary atherosclerosis may have incomplete suppression of TxA2 production despite chronic ASA therapy. This finding suggests that additional efforts should be made to lower TxA2 levels in patients with widespread coronary artery disease.

Intracoronary microparticles and microvascular obstruction in patients with ST elevation myocardial infarction undergoing primary percutaneous intervention.

AIMS: Microparticles (MP) are cell-derived fragments known to be increased in the blood of patients with acute coronary syndromes. We aimed to assess, in ST elevation myocardial infarction (STEMI), the systemic and local (in the culprit coronary artery) levels of platelet-derived MP (PMP, CD42+CD31+) and endothelial-derived MP (EMP, CD42-CD31+) and their relation to indexes of microvascular obstruction (MVO). METHODS AND RESULTS: In 78 STEMI patients undergoing successful primary percutaneous coronary intervention, blood samples were sequentially drawn from the aorta and the culprit coronary artery for cytofluorimetric MP detection. Thrombolysis in myocardial infarction (TIMI) flow, thrombus score (TS), corrected TIMI frame count (cTFC), myocardial blush grade (MBG), quantitative blush evaluator (QuBE) score, and 90 min ST resolution (ΣSTR) were calculated. Both PMP and EMP levels were significantly higher in the intracoronary than in the aortic blood samples. Intracoronary PMP and EMP levels were positively related to TS and cTFC and inversely related to MBG and QuBE. Aortic PMP (but not EMP) levels were related to TS and cTFC and, inversely, to QuBE. Intracoronary PMP were independently related to angiographic and electrocardiographic MVO in a multivariate model. CONCLUSION: The correlations of intracoronary EMP and of both systemic and intracoronary PMP levels with TS support the role of MP as markers of ongoing thrombosis. Moreover, the correlation of intracoronary MP with indexes of microvascular dysfunction suggests, for the first time, a possible direct role of MP in the pathogenesis of MVO.