Distal embolization during primary angioplasty: histopathologic features and predictability

Association of Coronary Microvascular Rarefaction and Myocardial Fibrosis With Coronary Artery Disease

BACKGROUND

To evaluate, in a cohort study, whether coronary microvasculature and myocardial structure differ between people with and without coronary artery disease (CAD).

METHODS AND RESULTS

We performed histological analysis of left ventricle free wall obtained at autopsy from 25 men and 23 women with ≥1 coronary artery with ≥75% area stenosis, and 25 men and 25 women without (no or minimal) CAD, matched for sex and age, who died suddenly from noncardiac causes. Decedents with myocardial infarction or other cardiac abnormality were excluded. Decedents with and without CAD had similar height and weight. Heart weight of decedents with CAD was higher than that of decedents without CAD (mean, 391 versus 364 g; mean difference, 27 g [95% CI, 0.3-54.0], P=0.048). Decedents with CAD had lower arteriole density (mean, 1.4 per mm2 versus 1.8 per mm2; mean difference, -0.4 per mm2 [95% CI, -0.6 to -0.2], P=0.0001), lower capillary length density (mean, 3164 versus 3701 mm/mm3; mean difference, -537 [95% CI, -787 to -286], P<0.0001), and higher total myocardial fibrosis (mean, 7.5% versus 5.7%; mean difference, 1.7% [95% CI, 1.0-2.5], P<0.0001), than decedents without CAD.

CONCLUSIONS

CAD was associated with coronary microvascular rarefaction and increased myocardial fibrosis. The association of CAD with coronary microvascular rarefaction and increased myocardial fibrosis may contribute to the increased risks of death, myocardial infarction and heart failure that accompany CAD, and may attenuate the impact of percutaneous coronary intervention on cardiovascular risk in people with stable angina.

The Use of Thrombectomy during Primary Percutaneous Coronary Intervention: Resurrecting an Old Concept in Contemporary Practice

Optimal myocardial reperfusion during primary percutaneous coronary intervention (pPCI) is increasingly recognized to be beyond restoring epicardial coronary flow. Both invasive and non-invasive tools have highlighted the limitation of using this metric, and more efforts are focused towards achieving optimal reperfusion at the level of the microcirculation. Recent data highlighted the close relationship between thrombus burden and impaired microcirculation in patients presenting with ST-segment elevation myocardial infarction (STEMI). Moreover, distal embolization was an independent predictor of mortality in patients with STEMI. Likewise, the development of no-reflow phenomenon has been directly linked with worse clinical outcomes. Adjunctive thrombus aspiration during pPCI is intuitively intended to remove atherothrombotic material to mitigate the risk of distal embolization and the no-reflow phenomenon (NRP). However, prior trials on the use of thrombectomy during pPCI did not support its routine use, with comparable clinical endpoints to patients who underwent PCI alone. This article aims to review the existing literature highlighting the limitation on the use of thrombectomy and provide future insights into trials investigating the role of thrombectomy in contemporary pPCI.

The impact of primary percutaneous coronary intervention strategies during ST-elevation myocardial infarction on the prevalence of coronary microvascular dysfunction

Coronary microvascular dysfunction (CMD) is a common complication of ST-segment elevation myocardial infarction (STEMI) and can lead to adverse cardiovascular events. This is a non-randomized, observational, prospective study of STEMI patients with multivessel disease who underwent primary PCI, grouped based on whether they underwent balloon pre-dilatation stenting or direct stenting of the culprit lesion. Coronary physiology measurements were performed 3 months post-PCI including coronary flow reserve (CFR) and index of microcirculatory resistance (IMR) measurements at the culprit vessel. The primary endpoint was the prevalence of CMD at 3 months, defined as IMR ≥ 25 or CFR < 2.0 with a normal fractional flow reserve. Secondary endpoints included major adverse cardiovascular events (MACE) at 12 months. Two hundred ten patients were enrolled; most were men, 125 (59.5%), with a median age of 65 years. One hundred twelve (53.2%) underwent balloon pre-dilatation before stenting, and 98 (46.7%) underwent direct stenting. The prevalence of CMD at 3 months was lower in the direct stenting group than in the balloon pre-dilatation stenting group (12.24% vs. 40.18%; p < 0.001). Aspiration thrombectomy and administration of intracoronary glycoprotein IIb/IIIa inhibitors were associated with lower odds of CMD (OR = 0.175, p = 0.001 and OR = 0.113, p = 0.001, respectively). Notably, MACE in patients who underwent direct stenting was lower than in those who underwent balloon pre-dilatation before stenting (14.29% vs. 26.79%; p = 0.040). In STEMI patients with multivessel disease, direct stenting of the culprit lesion, aspiration thrombectomy and administration of intracoronary glycoprotein IIb/IIIa inhibitors were associated with a lower prevalence of CMD at 3 months and lower incidence of MACE at 12 months compared with balloon pre-dilatation stenting.This trial is registered at https://ichgcp.net/clinical-trials-registry/NCT05406297 .

The prognostic value of admission D-dimer level in patients with cardiogenic shock after acute myocardial infarction

Background

Shock is associated with the activation of the coagulation and fibrinolytic system, and D-dimer is the degradation product of cross-linked fibrin. However, the prognostic value of D-dimer in patients with cardiogenic shock (CS) after acute myocardial infarction (AMI) remains unclear.

Methods

We retrospectively analyzed the data of consecutive patients with CS complicating AMI. The primary endpoint was 30-day mortality and the secondary endpoint was the major adverse cardiovascular events (MACEs) including 30-day all-cause mortality, ventricular tachycardia/ventricular fibrillation, atrioventricular block, gastrointestinal hemorrhage, and non-fatal stroke. Restricted cubic spline (RCS) analyses were performed to assess the association between admission D-dimer and outcomes. A multivariable Cox regression model was performed to identify independent risk factors. The risk predictive potency with D-dimer added to the traditional risk scores was evaluated by C-statistics and the net reclassification index.

Results

Among 218 patients with CS complicating AMI, those who died during the 30-day follow-up presented with worse baseline characteristics and laboratory test results, including a higher level of D-dimer. According to the X-tile program result, the continuous plasma D-dimer level was divided into three gradients. The 30-day all-cause mortality in patients with low, medium, and high levels of D-dimer were 22.4, 53.3, and 86.2%, respectively (p < 0.001 for all). The 30-day incidence of MACEs was 46.3, 77.0, and 89.7%, respectively (p < 0.001). In the multivariable Cox regression model, the trilogy of D-dimer level was an independent risk predictor for 30-day mortality (median D-dimer cohort: HR 1.768, 95% CI 0.982-3.183, p = 0.057; high D-dimer cohort: HR 2.602, 95% CI 1.310-5.168, p = 0.006), a similar result was observed in secondary endpoint events (median D-dimer cohort: HR 2.012, 95% CI 1.329-3.044, p = 0.001; high D-dimer cohort: HR 2.543, 95% CI 1.452-4.453, p = 0.001). The RCS analyses suggested non-linear associations of D-dimer with 30-day mortality. The enrollment of D-dimer improved risk discrimination for all-cause death when combined with the traditional CardShock score (C-index: 0.741 vs. 0.756, p _difference = 0.004) and the IABP-SHOCK II score (C-index: 0.732 vs. 0.754, p _difference = 0.006), and the GRACE score (C-index: 0.679 vs. 0.715, p _difference < 0.001). Similar results were acquired after logarithmic transformed D-dimer was included in the risk score. The improvements in reclassification which were calculated as additional net reclassification index were 7.5, 8.6, and 12.8%, respectively.

Conclusion

Admission D-dimer level was independently associated with the short-term outcome in patients with CS complicating AMI and addition of D-dimer brought incremental risk prediction value to traditional risk prediction scores.

Statin Use in Cancer Patients with Acute Myocardial Infarction and Its Impact on Long-Term Mortality

Statin use and its impact on long-term clinical outcomes in active cancer patients following acute myocardial infarction (MI) remains insufficiently elucidated. Of the 1011 consecutive acute MI patients treated invasively between 2012 and 2017, cancer was identified in 134 (13.3%) subjects. All patients were observed within a median follow-up of 69.2 (37.8−79.9) months. On discharge, statins were prescribed less frequently in MI patients with cancer as compared to the non-cancer MI population (79.9% vs. 91.4%, p < 0.001). The most common statin in both groups was atorvastatin. The long-term mortality was higher in MI patients not treated vs. those treated with statins, both in non-cancer (29.5%/year vs. 6.7%/year, p < 0.001) and cancer groups (53.9%/year vs. 24.9%/year, p < 0.05), respectively. Patient’s age (hazard ratio (HR) 1.04, 95% confidence interval (CI) 1.03−1.05, p < 0.001, per year), an active cancer (HR 2.42, 95% CI 1.89−3.11, p < 0.001), hemoglobin level (HR 1.14, 95% CI 1.09−1.20, p < 0.001, per 1 g/dL decrease), and no statin on discharge (HR 2.13, 95% CI 1.61−2.78, p < 0.001) independently increased long-term mortality. In MI patients, simultaneous diagnosis of an active cancer was associated with less frequently prescribed statins on discharge. Irrespective of cancer diagnosis, no statin use was found as an independent predictor of increased long-term mortality.

Development and Validation of a Novel Risk Stratification Model for Slow-Flow/No-Reflow During Primary Percutaneous Coronary Intervention (the RK-SF/NR Score)

In this study, we developed and validated a novel risk stratification model to predict slow-flow/no-reflow (SF/NR) during the primary percutaneous coronary intervention (PCI), namely the RK-SF/NR score. A total of 1,711 consecutive patients with ST-segment elevation myocardial infarction (STEMI) undergone primary PCI. A novel risk stratification model was developed in the development dataset and tested in the validation dataset. The overall incidence rate of SF/NR during the procedure was 28.8% (493/1,711). The final solution consisted of 9 variables: female gender (points = 2), total ischemic time ≥8 hours (points = 1), cardiac arrest at presentation (points = 2), left ventricular end-diastolic pressure ≥24 mm Hg (points = 3), left ventricular ejection fraction ≤30% (points = 2), culprit proximal left anterior descending artery (points = 3), thrombus grade ≥4 (points = 6), preprocedure thrombolysis in myocardial infarction (TIMI) 0 flow (points = 2), and lesion length ≥35 mm (points = 3). In the validation set, the area under the curve the RK-SF/NR score was 0.775 (0.722 to 0.829) and a score ≥10 has sensitivity of 77.9% (68.2% to 85.8%), negative predictive value of 87.3% (82.3% to 91.0%), specificity of 62.6% (56.0% to 68.9%), and positive predictive value of 46.3% (41.4% to 51.2%). In conclusion, RK-SF/NR score had shown good discriminating power for predicting SF/NR during primary PCI with good sensitivity and negative predictive value. Hence, the proposed model can have good clinical utility for screening patients at high risk of developing SF/NR during primary PCI.

Thiols and disulfide levels are correlated with TIMI thrombus grade in non-ST elevation myocardial infarction patients

Aim: We investigated the relationship between thrombolysis in myocardial infarction (TIMI) thrombus grade and thiol/disulfide levels. Materials & methods: 182 non-ST elevation myocardial infarction (NSTEMI) patients were divided into two groups; TIMI grade 0 patients who do not have any visible thrombus in their culprit vessels, and TIMI thrombus grade 1-5 patients. Results: Native and total thiol levels and disulfide to thiol ratio were higher in the low thrombus group. In addition, thrombus grade was positively correlated with disulfide to native and total thiol ratio and negatively with native and total thiol levels in NSTEMI patients. Conclusion: We can assert that thiol levels tend to decrease, and the disulfide to thiol ratio increase with increasing thrombus burden in NSTEMI patients.

A fresh look at coronary microembolization

Mechanical stress from haemodynamic perturbations or interventional manipulation of epicardial coronary atherosclerotic plaques with inflammatory destabilization can release particulate debris, thrombotic material and soluble substances into the coronary circulation. The physical material obstructs the coronary microcirculation, whereas the soluble substances induce endothelial dysfunction and facilitate vasoconstriction. Coronary microvascular obstruction and dysfunction result in patchy microinfarcts accompanied by an inflammatory reaction, both of which contribute to progressive myocardial contractile dysfunction. In clinical studies, the benefit of protection devices to retrieve atherothrombotic debris during percutaneous coronary interventions has been modest, and the treatment of microembolization has mostly relied on antiplatelet and vasodilator agents. The past 25 years have witnessed a relative proportional increase in non-ST-segment elevation myocardial infarction in the presentation of acute coronary syndromes. An associated increase in the incidence of plaque erosion rather than rupture has also been recognized as a key mechanism in the past decade. We propose that coronary microembolization is a decisive link between plaque erosion at the culprit lesion and the manifestation of non-ST-segment elevation myocardial infarction. In this Review, we characterize the features and mechanisms of coronary microembolization and discuss the clinical trials of drugs and devices for prevention and treatment.

Vitamin D level predicts angiographic no-reflow phenomenon after percutaneous coronary intervention in patients with ST segment elevation myocardial infarction

Aim: No-reflow phenomenon (NRP) is an undesirable result of coronary interventions, and usually occurred during the primary percutaneous coronary intervention (PPCI). On the other hand, there is growing evidence of epidemiological studies suggest that serum 25 hydroxy-vitamin D (25(OH)D3) level is significantly associated with cardiovascular mortality and morbidity. Objective: To investigate whether there is a relationship between admission serum 25(OH)D3 levels and NRP in patients with ST elevation myocardial infarction (STEMI). Methods: This study consisted of 496 consecutive acute STEMI patients who underwent PPCI. After the restoration of antegrade flow, the patients were divided into the normal flow and no-reflow groups. No-reflow defined as; thrombosis in myocardial infarction (TIMI) flow grade ≤2, or a TIMI flow grade = 3 with a myocardial perfusion grade ≤1. Results: Angiographic no-reflow occurred 18.2% of all study patients. Serum 25(OH)D3 levels were significantly lower when compared with the normal flow group (14.6 ± 7.3 vs 22.6 ± 9.6 ng/ml; p < 0.001). 25(OH)D3 level was significantly negatively correlated with Neutrophil/lymphocyte (N/L) ratio. In multivariate analysis, 25(OH)D3 level on admission (OR: 0.738; 95% CI: 0.584-0.878; p = 0.001) was found an independent predictor of NRP together with N/L ratio, N-Terminal-proBNP, balloon pre dilatation and syntax score I. On receiver operating curve analysis (ROC), the cut-off value of admission 25(OH)D3 level was 10.5 ng/ml for the prediction of NRP with a sensitivity of 93% and specificity of 68%. The area under the ROC curve (AUC) was 0.772 (95% CI: 0.697-0.846; p < 0.001). Conclusion: We have shown that lower 25(OH)D3 level on admission is associated with higher NRP frequency and may be used as a predictor for NRP in STEMI patients undergoing PPCI.

[The no-Reflow Phenomenon During Primary Percutaneous Coronary Intervention in Patients With ST-Segment Elevation Myocardial Infarction due to Massive Coronary Thrombosis. Pathogenesis and Predictors of no-Reflow]

Despite successful and timely revascularization of the infarct-related artery, myocardial tissue remains underperfused in some patients. This condition is known as the no-reflow phenomenon, which is associated with a worse prognosis. The first part of the systematic review on no-reflow focuses on description of the no-reflow pathogenesis and predictors. This phenomenon has a complicated, multifactorial pathogenesis, including distal embolization, ischemic injury, reperfusion injury, and a component of individual predisposition. Meanwhile, this phenomenon undergoes spontaneous regression in some patients. Several studies have demonstrated the role of definite biomarkers and clinical indexes as risk predictors for no-reflow. The significance of each pathogenetic component of no-reflow is suggested to be different in different patients, which may warrant an individualized approach in the treatment.

Small lipid core burden index in patients with stable angina pectoris is also associated with microvascular dysfunction: Insights from intracoronary electrocardiogram

Near-infrared spectroscopy with intravascular ultrasound (NIRS)-IVUS enables precise detection of lipid core burden. Intracoronary electrocardiography (ECG) can detect slight ischemia during percutaneous coronary intervention (PCI), indicating microvascular dysfunction (MD) by distal embolization, etc. Thus, this study aimed to investigate whether plaques with a low max-lipid core burden index (LCBI) at 4 mm (LCBI4mm) influence MD, using intracoronary ECG. We enrolled 40 consecutive patients who underwent PCI for stable angina pectoris (SAP) due to stenosis of the proximal segment of the left anterior descending artery in this study. Max-LCBI4mm was measured for each culprit lesion. Gray-scale IVUS data including plaque burden were measured. Intracoronary ECG was performed to measure the time from the initiation of ST-segment elevation from the isoelectric baseline after stent balloon inflation to the return of the ST-segment to the isoelectric baseline after the deflation of the stent balloon, which was defined as the severity of the MD. The patients were divided into two groups according to median max-LCBI4mm of 120 as follows: low- [n = 20] and high- [n = 20] LCBI groups. The overall mean Max-LCBI4mm was 120 ± 86. No differences in baseline characteristics, including prevalence of dyslipidemia, were found between both groups, as well as in the gray-scale IVUS parameters. The severity of the MD was greater in the high-LCBI group than in the low-LCBI group (16.6 ± 9.1 vs 4.7 ± 4.8 s, P < 0.01). The no-reflow and slow-flow phenomena were not observed. Even max-LCBI4mm value <400 on NIRS-IVUS was associated with MD during PCI in patients with SAP.

Rosuvastatin protects against coronary microembolization-induced cardiac injury via inhibiting NLRP3 inflammasome activation

Coronary microembolization (CME), a common reason for periprocedural myocardial infarction (PMI), bears very important prognostic implications. However, the molecular mechanisms related to CME remain largely elusive. Statins have been shown to prevent PMI, but the underlying mechanism has not been identified. Here, we examine whether the NLRP3 inflammasome contributes to CME-induced cardiac injury and investigate the effects of statin therapy on CME. In vivo study, mice with CME were treated with 40 mg/kg/d rosuvastatin (RVS) orally or a selective NLRP3 inflammasome inhibitor MCC950 intraperitoneally (20 mg/kg/d). Mice treated with MCC950 and RVS showed improved cardiac contractile function and morphological changes, diminished fibrosis and microinfarct size, and reduced serum lactate dehydrogenase (LDH) level. Mechanistically, RVS decreased the expression of NLRP3, caspase-1, interleukin-1β, and Gasdermin D N-terminal domains. Proteomics analysis revealed that RVS restored the energy metabolism and oxidative phosphorylation in CME. Furthermore, reduced reactive oxygen species (ROS) level and alleviated mitochondrial damage were observed in RVS-treated mice. In vitro study, RVS inhibited the activation of NLRP3 inflammasome induced by tumor necrosis factor α plus hypoxia in H9c2 cells. Meanwhile, the pyroptosis was also suppressed by RVS, indicated by the increased cell viability, decreased LDH and propidium iodide uptake in H9c2 cells. RVS also reduced the level of mitochondrial ROS generation in vitro. Our results indicate the NLRP3 inflammasome-dependent cardiac pyroptosis plays an important role in CME-induced cardiac injury and its inhibitor exerts cardioprotective effect following CME. We also uncover the anti-pyroptosis role of RVS in CME, which is associated with regulating mitochondrial ROS.

Tirofiban combined with heparin's effect and safety in the treatment of mild to moderate acute ischemic stroke

Tirofiban can be used to treat patients with acute ischemic stroke (AIS), this study was to evaluate the efficacy and safety of tirofiban combined with heparin in the treatment of mild to moderate AIS. A total of 98 patients with mild to moderate AIS randomly were divided into 2 groups within 48 h: the treatment group treated with tirofiban and, and the control group treated with aspirin + clopidogrel. The treatment group was given the same scheme as the control group after the treatment of tirofiban combined with heparin for 48 h. It was found that, compared with the control group, a significant decreased National Institute of Health stroke scale (NIHSS) was found in 48 h and 14 d, especially to the Barthel index (BI) in the treatment group (P < 0.05). Furthermore, Modified Rankin Scale (MRS, ≤2) in the treatment group was significantly upregulated in 90 d (P < 0.05). However, there were no significant differences in the adverse drug reactions between the two groups. It was indicated that nerve function and long-term prognosis in patients undergoing heparin for mild to moderate AIS were obviously improved than the control group.

D-dimers are associated with coronary artery disease severity assessed using Syntax and Syntax II scores in patients with ST elevation myocardial infarction

INTRODUCTION AND OBJECTIVES

D-dimers are a determinant of hypercoagulable state and have been found to be related to acute coronary syndromes. We aimed to establish the association between increased D-dimer levels and coronary artery disease (CAD) severity using SYNTAX Score (SS) II in patients with ST elevation myocardial infarction (STEMI) who underwent primary percutaneous coronary intervention (PCI).

METHODS

This retrospective study included 300 consecutive patients (81.7% males, mean age 55±12 years) with STEMI who underwent a primary PCI. Patients were divided into two groups according to their median SSII [SSII<25 as a low group (n=151) and SSII≥25 as a high group (n=149)]. Blood samples for D-dimers and the other biochemical parameters were obtained from each patient at admission.

RESULTS

When compared with the low SSII group, frequency of female gender, no-reflow phenomenon, D-dimer levels, thrombus score, creatine kinase MB and troponin were significantly higher, whereas left ventricular ejection fraction (LVEF) and glomerular filtration rate (GFR) were lower in the high SSII group (p<0.05, for all). D-dimer levels, thrombus score, LVEF, GFR and no-reflow phenomenon were independent predictors of CAD severity (p<0.05, for all). Receiver operating characteristic curve analysis showed that the D-dimer cut-off value for predicting the severity of CAD was 0.26 μg/ml (69.8% sensitivity and 65.6% specificity, p<0.001).

CONCLUSION

Increased D-dimer levels are associated with the severity of CAD based on Syntax Score II, in patients with STEMI who successfully underwent revascularization with a primary PCI.

No-reflow phenomenon in ST-segment elevation myocardial infarction: still the Achilles' heel of the interventionalist

Improvements in systems, technology and pharmacotherapy have significantly changed the prognosis over recent decades in patients presenting with ST-segment elevation myocardial infarction. These clinical achievements have, however, begun to plateau and it is becoming increasingly necessary to consider novel strategies to further improve outcomes. Approximately a third of patients treated by primary percutaneous coronary intervention for ST-segment elevation myocardial infarction will suffer from coronary no-reflow (NR), a condition characterized by poor myocardial perfusion despite patent epicardial arteries. The presence of NR impacts significantly on clinical outcomes including left ventricular dysfunction, heart failure and death, yet conventional management algorithms neither assess the risk of NR nor treat NR. This review will provide a contemporary overview on the pathogenesis, diagnosis and treatment of NR.

D-Dimer Level Predicts Angiographic No-Reflow Phenomenon After Percutaneous Coronary Intervention Within 2-7 Days of Symptom Onset in Patients with ST-Segment Elevation Myocardial Infarction

It remains uncertain whether plasma D-dimer level can predict no-reflow in patients with STEMI who had pPCI after 48 h of symptom onset. This study retrospectively enrolled 229 consecutive patients who had pPCI for acute STEMI within 2-7 days of symptom onset between January 2008 and December 2018. Patients were divided into no-reflow group (TIMI flow grade 0-2) and reflow group (TIMI flow grade 3). Predictors of no-reflow were assessed by univariate and multivariate binary logistic regression analyses. Plasma D-dimer level can independently predict no-reflow in patients with STEMI who had pPCI within 2-7 days of symptom onset (OR 2.52 per 1 mg/L increase, 95% CI 1.16-5.47, p = 0.019). This finding indicated that pPCI may be safe and feasible for STEMI patients within 2-7 days of symptom onset with low D-dimer level. Graphical Abstract Plasma D-dimer level can independently predict no-reflow in patients with STEMI who had pPCI within 2-7 days of symptom onset. pPCI may be safe and feasible for STEMI patients within 2-7 days of symptom onset with low D-dimer level.

Dual quantitative coronary angiography accurately quantifies intracoronary thrombotic burden in patients with acute coronary syndrome: Comparison with optical coherence tomography imaging

BACKGROUND

Dual quantitative coronary angiography (QCA) has been recently tested for assessment of intracoronary thrombus volume in experimental models. The present study aimed to validate dual QCA in vivo for the assessment of thrombus burden by exploring the correlations between dual QCA-thrombus volume and optical coherence tomography (OCT)-derived indices of thrombotic burden.

METHODS AND RESULTS

Fifty-one patients with ACS and angiographic evidence of thrombus undergoing OCT of the culprit lesion before stenting were included. Dual QCA-thrombus volume was calculated as difference between edge-detection and video-densitometry area functions along the target segment. Culprit lesion was categorized using the Ambrose's and AHA/ACC angiographic classifications. Thrombus volume (mean thrombus area × thrombus length), thrombus burden [(mean thrombus area/mean lumen area) x100] and Prati thrombus score (number of quadrants with thrombus) were measured by OCT, and the presence of plaque rupture (PR) or intact fibrous cap (IFC) was assessed. Dual QCA-thrombus volume correlated significantly with OCT-thrombus volume (R = 0.791), thrombus burden (R = 0.767) and Prati thrombus score (R = 0.600) (all p < 0.001). Dual-QCA thrombus volume was significantly higher in patients with PR compared with those with IFC (3.48 mm³ [1.45-11.26] vs. 1.69 mm³ [0.09-5.02], p = 0.013). Compared with IFC, PR showed higher prevalence of eccentric type II Ambrose lesion (41.7% vs. 7.4%, p = 0.004), complex B2/C lesion (87.5% vs. 55.6%, p = 0.012), and heavy calcification (29.2% vs. 3.7%, p = 0.013).

CONCLUSIONS

Dual QCA analysis appears to be a promising tool for quantification of intracoronary thrombus in vivo. This novel methodology may be useful to guide intracoronary thrombus removal during percutaneous coronary intervention and to aid prognostic stratification in patients with ACS.

Colloids, nanoparticles, and materials for imaging, delivery, ablation, and theranostics by focused ultrasound (FUS)

This review focuses on different materials and contrast agents that sensitize imaging and therapy with Focused Ultrasound (FUS). At high intensities, FUS is capable of selectively ablating tissue with focus on the millimeter scale, presenting an alternative to surgical intervention or management of malignant growth. At low intensities, FUS can be also used for other medical applications such as local delivery of drugs and blood brain barrier opening (BBBO). Contrast agents offer an opportunity to increase selective acoustic absorption or facilitate destructive cavitation processes by converting incident acoustic energy into thermal and mechanical energy. First, we review the history of FUS and its effects on living tissue. Next, we present different colloidal or nanoparticulate approaches to sensitizing FUS, for example using microbubbles, phase-shift emulsions, hollow-shelled nanoparticles, or hydrophobic silica surfaces. Exploring the science behind these interactions, we also discuss ways to make stimulus-responsive, or "turn-on" contrast agents for improved selectivity. Finally, we discuss acoustically-active hydrogels and membranes. This review will be of interest to those working in materials who wish to explore new applications in acoustics and those in acoustics who are seeking new agents to improve the efficacy of their approaches.

Coronary artery ectasia, an independent predictor of no-reflow after primary PCI for ST-elevation myocardial infarction

BACKGROUND

The no-reflow phenomenon is a serious complication after primary percutaneous coronary intervention (PCI) for ST-elevation Myocardial Infarction (STEMI). Coronary artery ectasia (CAE) may increase the risk of no-reflow, however, only limited data is available on the potential impact of CAE. The aim of this study was to determine the potential association between CAE and no-reflow after primary PCI.

METHODS

A case control study was performed based on a prospective cohort of STEMI patients from January 2000 to December 2011. All patients with TIMI 0-1 flow post primary PCI, in the absence of dissection, thrombus, spasm or high-grade residual stenosis, were considered as no-reflow case. Control subjects were two consecutive STEMI patients after each case, with TIMI flow ≥2 after primary PCI. CAE was defined as dilatation of an arterial segment to a diameter at least 1.5 times that of the adjacent normal coronary artery.

RESULTS

In the no-reflow group, frequency of CAE was significantly higher (33.8% vs 3.9%, p < 0.001) compared to the control group. Baseline variables were comparable between patients with and without CAE. Patients with CAE had more often TIMI 0-1 flow pre-PCI (91% vs 71% p = 0.03), less often anterior STEMI (3% vs 37%, p < 0.001) and underwent significantly less often a PCI with stenting (47% vs 74%, p = 0.003). After multivariate analysis, CAE remained a strong and independent predictor of no-reflow (OR 13.9, CI 4.7-41.2, p < 0.001).

CONCLUSION

CAE is a strong and independent predictor of no-reflow after primary PCI for STEMI. Future studies should assess optimal treatment.

Contrast agent dose and slow/no-reflow in percutaneous coronary interventions : A case-control study of patients with non-ST-segment elevation acute coronary syndromes

BACKGROUND

The angiographic slow/no-reflow phenomenon after primary percutaneous coronary intervention carries a poor prognosis for patients with non-ST-segment elevation acute coronary syndrome (NSTEACS). There is evidence that contrast agents cause endothelial dysfunction, myocardial cell damage, and coronary spasms. We hypothesized that the contrast agent dose may be related to slow/no-reflow in patients with NSTEACS undergoing percutaneous transluminal coronary angioplasty and stent (PTCA + stent).

PATIENTS AND METHODS

We enrolled 3369 patients with NSTEACS who underwent PTCA + stent only in the culprit vessel for the first time from September 2007 to May 2017 in this study. Coronary blood flow of ≤TIMI grade 2 after PTCA + stent was defined as slow/no-reflow. The relationship between the contrast agent dose and slow/no-reflow phenomenon was analyzed by multivariate conditional logistic regression and smooth curve fitting.

RESULTS

In multivariable conditional logistic regression analysis, the contrast agent dose was found to be an independent risk factor for slow/no-reflow after adjusting for the number of stents and the thrombus burden (OR: 1.0112; 95% CI: 1.0049-1.0176; p < 0.0001), and after adjusting for type 2 diabetes mellitus, NSTEACS risk stratification, application of platelet glycoprotein (GP) IIB/IIIA receptor antagonists, type of contrast agent, number of balloon dilatations, number of stents, and thrombus burden (OR: 1.0113; 95% CI: 1.0036-1.0191; p = 0.004). Further, the risk of slow/no-reflow increased significantly with the contrast agent level up to the inflection point of 160 ml.

CONCLUSION

The contrast agent dose may be a risk factor for slow/no-reflow phenomenon after PTCA + stent in patients with NSTEACS. When the dose was greater than 160 ml, the risk of slow/no-reflow increased significantly.

Relation of Low-Density Lipoprotein Cholesterol With Microvascular Injury and Clinical Outcome in Revascularized ST-Elevation Myocardial Infarction

BACKGROUND

Microvascular injury (MVI) after primary percutaneous coronary intervention for ST-elevation myocardial infarction (STEMI) is a major determinant of adverse clinical outcome. Experimental data indicate an impact of hypercholesterolemia on MVI; however, there is a lack of clinical studies confirming this relation. We aimed to investigate the association of cholesterol concentrations on admission with MVI visualized by cardiac magnetic resonance imaging and clinical outcome in STEMI patients treated by primary percutaneous coronary intervention.

METHODS AND RESULTS

In this prospective, observational study, we included 235 consecutive revascularized STEMI patients. Cholesterol (total cholesterol, low-density lipoprotein [LDL], and high-density lipoprotein cholesterol) and triglyceride concentrations were determined at presentation. Cardiac magnetic resonance scans were performed 2 (2-4) days after infarction to assess infarct characteristics, including MVI. Clinical end point was the occurrence of major adverse cardiac events (MACE) comprising all-cause mortality, nonfatal reinfarction, and new congestive heart failure. Patients with MVI (n=129; 55%) showed higher levels of total cholesterol (204 [172-226] versus 185 [168-212] mg/dL; P=0.01) and LDL cholesterol (142 [113-166] versus 118 [103-149] mg/dL; P=0.001), whereas high-density lipoprotein cholesterol and triglycerides did not differ significantly. In multivariable analysis, including all significant clinical and cardiac magnetic resonance determinants of MVI, LDL concentration emerged as an independent predictor of MVI (odds ratio, 1.02 [95% confidence interval, 1.01-1.02]; P=0.002). Furthermore, increased LDL cholesterol (>150 mg/dL) significantly predicted the occurrence of major adverse cardiac events (hazard ratio, 3.09 [95% confidence interval, 1.22-7.87]; P=0.01).

CONCLUSIONS

In STEMI patients undergoing primary percutaneous coronary intervention, baseline LDL cholesterol concentrations were independently associated with MVI, revealing a clinically relevant link between LDL metabolism and MVI in acute STEMI.

PRotective Effect on the coronary microcirculation of patients with DIabetes by Clopidogrel or Ticagrelor (PREDICT): study rationale and design. A randomized multicenter clinical trial using intracoronary multimodal physiology

Background

In diabetic patients a predisposed coronary microcirculation along with a higher risk of distal particulate embolization during primary percutaneous intervention (PCI) increases the risk of peri-procedural microcirculatory damage. However, new antiplatelet agents, in particular Ticagrelor, may protect the microcirculation through its adenosine-mediated vasodilatory effects.

Methods

PREDICT is an original, prospective, randomized, multicenter controlled study designed to investigate the protective effect of Ticagrelor on the microcirculation during PCI in patient with diabetes mellitus type 2 or pre-diabetic status. The primary endpoints of this study aim to test (i) the decrease in microcirculatory resistance with antiplatelet therapy (Ticagrelor > Clopidogrel; mechanistic effect) and (ii) the relative microcirculatory protection of Ticagrelor compared to Clopidogrel during PCI (Ticagrelor < Clopidogrel; protective effect).

Conclusions

PREDICT will be the first multicentre clinical trial to test the adenosine-mediated vasodilatory effect of Ticagrelor on the microcirculation during PCI in diabetic patients. The results will provide important insights into the prospective beneficial effect of this drug in preventing microvascular impairment related to PCI (http://www.clinicaltrials.gov No. NCT02698618).

Electronic supplementary material

The online version of this article (doi:10.1186/s12933-017-0543-5) contains supplementary material, which is available to authorized users.

Lymphocyte Communication in Myocardial Ischemia/Reperfusion Injury

SIGNIFICANCE

Myocardial ischemia/reperfusion (I/R) is an important complication of reperfusion therapy for myocardial infarction (MI). It is a complex process involving metabolic and immunological factors. To date, no effective treatment has been identified. Recent Advances: Previous research has focused on the role of innate immune cells in I/R injury. In recent years, increasing evidence has accumulated for an important role for adaptive immune cells, particularly T lymphocytes. Data from ST elevation MI patients have identified prognostic significance for lymphocyte counts, particularly postreperfusion lymphopenia. Dynamic changes in circulating CD4⁺ T cell subsets occurring early after reperfusion are associated with development of I/R injury in the form of microvascular obstruction. Transcoronary gradients in cell counts suggest sequestration of these cells into the reperfused myocardium. These findings support existing data from mouse models indicating a role for CD4⁺ T cells in I/R injury. It is clear, however, the effects of lymphocytes in the ischemic myocardium are time and subset specific, with some having protective effects, while others are pathogenic.

CRITICAL ISSUES

An understanding of the cellular events that lead to accumulation of lymphocytes in the myocardium, and their actions once there, is key to manipulating this process. Chemokines produced in response to ischemia and cellular injury have an important role, while lymphocyte-derived cytokines are critical in the balance between inflammation and healing.

FUTURE DIRECTIONS

Further research into the involvement of lymphocytes in myocardial I/R injury may allow development of targeted therapies, opening a new avenue of considerable therapeutic potential. Antioxid. Redox Signal. 26, 660-675.

Expert Opinion: Optimising Stent Deployment in Contemporary Practice: The Role of Intracoronary Imaging and Non-compliant Balloons

Final stent dimensions remain an important predictor of restenosis, target vessel revascularisation (TVR) and subacute stent thrombosis (ST), even in the drug-eluting stent (DES) era. Stent balloons are usually semi-compliant and thus even high-pressure inflation may not achieve uniform or optimal stent expansion. Post-dilatation with non-compliant (NC) balloons after stent deployment has been shown to enhance stent expansion and could reduce TVR and ST. Based on supporting evidence and in the absence of large prospective randomised outcome-based trials, post-dilatation with an NC balloon to achieve optimal stent expansion and maximal luminal area is a logical technical recommendation, particularly in complex lesion subsets.

Predictors and outcome of no-reflow post primary percutaneous coronary intervention for ST elevation myocardial infarction

Background

No-reflow (TIMI < 3) during primary PCI (PCI) for STEMI occurs in 11–41% of cases, indicates poor myocardial tissue perfusion, and is associated with a poor outcome. We aimed to determine predictors and 12 month outcomes of patients who developed no-reflow.

Methods

We analysed the PCI database of The Canberra Hospital and identified 781 patients who underwent primary PCI during 2008–2012. Follow-up at 12 months was with letter, phone call and review of hospital records.

Results

No-reflow was observed in 189 patients (25%) at the end of the procedure. Patients with no-reflow were older (64 vs. 61 years, p = 0.03). No-reflow patients were more likely to have initial TIMI flow < 3 (89% vs. 79%, p = 0.001), thrombus score ≥ 4 (83% vs. 69%, p = 0.0001), higher use of glycoprotein IIb/IIIa inhibitors (57% vs. 48%, p = 0.03) and longer median symptom to balloon time (223 min vs. 192 min, p = 0.004). No-reflow was an independent predictor of mortality (HR 1.95, CI 1.04-3.59, p = 0.037) during 12 month follow-up. On multivariate analysis, age > 60 years, thrombus score ≥ 4 and symptom to balloon time > 360 min were independent predictors of no-reflow. In 17% of cases of no reflow, it occurred only after stent insertion.

Conclusions

No-reflow occurred in 25% of STEMI patients undergoing primary PCI and was more likely with older age, high thrombus burden and delayed presentation. No-reflow was associated with a higher risk of death at 12 month follow-up.

Pre-PCI angiographic TIMI flow in the culprit coronary artery influences infarct size and microvascular obstruction in STEMI patients

OBJECTIVE

The influence of initial-thrombolysis in myocardial infarction (i-TIMI) coronary flow in the culprit coronary artery on myocardial infarct and microvascular obstruction (MVO) size is unclear. We assessed the impact on infarct size of i-TIMI flow in the culprit coronary artery, as well as on MVO incidence and size, by contrast-enhanced cardiac magnetic resonance (ce-CMR).

METHODS

In a prospective, multicenter study, pre-percutaneous coronary intervention (PCI) coronary occlusion was defined by an i-TIMI flow ≤1, and patency was defined by an i-TIMI flow ≥2. Infarct size, as well as MVO presence and size, were measured on ce-CMR 72h after admission.

RESULTS

A total of 140 patients presenting with ST-elevated myocardial infarction referred for primary PCI were included. There was no significant difference in final post-PCI TIMI flow between the groups (2.95±0.02 vs. 2.97±0.02, respectively; p=0.44). In the i-TIMI flow ≤1 group, infarct size was significantly larger (32±17g vs. 21±17g, respectively; p=0.002), MVO was significantly more frequent (74% vs. 53%, respectively; p=0.012), and MVO size was significantly larger [1.3 IQR (0; 7.1) vs. 0 IQR (0; 1.6)], compared to in the i-TIMI ≥2 patient group.

CONCLUSION

Initial angiographic TIMI flow in the culprit coronary artery prior to any PCI predicted final infarct size and MVO size: the better was the i-TIMI flow, the smaller were the infarct and MVO size.

Embolization after percutaneous coronary intervention in acute coronary syndrome. Saphenous vein grafts versus native coronary arteries

AIMS

The aim of this study was to assess the occurrence of distal embolization and to quantify the amount of embolic material captured during stent implantation in native coronary arteries, as compared with saphenous vein grafts (SVG) in patients at different time periods after an acute coronary syndrome.

PATIENTS AND METHODS

In all, 104 patients presenting with unstable or stable angina underwent percutaneous coronary intervention (PCI) in 107 vessels and stent implantation in 112 lesions, 53 % of which were in SVG.

RESULTS

Device deployment and retrieval was successful in 111 lesions. Embolic material was detected in 74 % of the protection devices. Early PCI, during a 2-week period after the last ischemic episode, was associated with larger embolic load, especially in the right coronary artery. The length of the lesion was the only preprocedural independent variable that was found to be a significant predictor for the presence of emboli (p = 0.002). The stent diameter and the maximum dilatation pressure were the two procedural variables found to be significant predictors for the presence of emboli (p = 0.025 and p = 0.008, respectively). The irregularity of the lesion and the number of stents deployed were found to have a predictive correlation to the total area of the embolic particles (p = 0.04 and p = 0.005, respectively).

CONCLUSION

Distal embolization of atherosclerotic debris is a frequent phenomenon after PCI not only in SVG but also in native vessels. The amount of embolic material seems to be related to the atherosclerotic burden of the vessel and to the early timing of the procedure as related to acute coronary syndrome.

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.

Thrombus age, clinical presentation, and reperfusion grade in myocardial infarction

INTRODUCTION

Autopsy studies show that dynamic coronary thrombosis leads to infarction. We studied intracoronary thrombus age in ST-segment elevation myocardial infarction (STEMI) and its relationship with clinical presentation and epicardial reperfusion grade.

METHODS AND RESULTS

Intracoronary thrombectomy was performed in 131 STEMI patients within 24 h after symptom onset, and material sufficient for pathological analysis was retrieved from 81 patients. Thrombus age was classified as fresh (<1day), lytic (1 to 5 days), or organized (>5days). A fresh thrombus was found in 48 patients (60%), whereas the thrombus showed lytic or organized changes in 33 patients (40%). Both thrombus and plaque material were aspirated in 40% of cases. Lytic or organized thrombi were aspirated in one third of the cases early (<12h) after symptom onset, and fresh thrombi were also aspirated in one third of STEMI of>12h evolution. In multivariable analysis, fresh thrombus was associated with both persistent ST-segment elevation (even after 12 h of onset) during percutaneous coronary intervention [odds ratio (OR) 4.23, 95% confidence interval (CI) 1.05-17.42, P=.042) and a previous history of ischemic heart disease (OR 4.54, 95% CI 1.41-14.64, P=.011). There were no associations between thrombus composition and epicardial reperfusion grade or the presence of the no-reflow phenomenon. Plaque components were found in all cases of distal embolization (5%).

CONCLUSION

Intracoronary thrombi aspirated in STEMI frequently show more than one stage of maturation. Fresh thrombi predominate in patients with known ischemic heart disease or persistent ST-segment elevation.

SUMMARY

In STEMI, thromboaspiration revealed thrombi at different stages of maturation, supporting a dynamic process of rupture and repair of the atherosclerotic plaque. Fresh thrombi were present more frequently within 12 h of infarction onset but also in patients with symptoms beyond 12 h. When containing plaque material, thrombi were often associated with macroscopic distal embolization during angioplasty.

A prospective randomized trial of thrombectomy versus no thrombectomy in patients with ST-segment elevation myocardial infarction and thrombus-rich lesions: MUSTELA (MUltidevice Thrombectomy in Acute ST-Segment ELevation Acute Myocardial Infarction) trial

OBJECTIVES

The aim of this study was to evaluate whether thrombectomy during primary percutaneous coronary intervention (pPCI) in patients with high thrombus burden improves myocardial reperfusion and reduces infarct size.

BACKGROUND

Thrombectomy aims at reducing distal thrombotic embolization during pPCI, improving myocardial reperfusion and clinical outcome.

METHODS

We randomized 208 patients with high thrombus burden in a 1:1 ratio to either pPCI with thrombectomy (Group T) or standard pPCI (Group S). Thrombectomy was performed with either rheolytic or manual aspiration catheters. Three-month magnetic resonance imaging was performed to assess infarct size and transmurality and microvascular obstruction (MVO). The primary endpoints were ST-segment elevation resolution (STR) >70% at 60 min and 3-month infarct size.

RESULTS

The baseline profile was similar between groups, except for a higher rate of initial Thrombolysis In Myocardial Infarction flow grade 3 in Group S (p = 0.002). Group T showed a significantly higher rate of STR (57.4% vs. 37.3%; p = 0.004) and of final myocardial blush 3 (68.3% vs. 52.9%; p = 0.03). Group T and Group S did not differ with regard to infarct size (20.4 ± 10.5% vs. 19.3 ± 10.6%; p = 0.54) and transmurality (11.9 ± 12.0% vs. 11.6 ± 12.7%; p = 0.92), but Group T showed significantly less MVO (11.4% vs. 26.7%; p = 0.02) and a higher prevalence of inhomogeneous scar (p < 0.0001). One-year freedom from major adverse cardiac events was similar between groups.

CONCLUSIONS

Thrombectomy as an adjunct to pPCI in patients with high thrombus load yielded better post-procedural STR and reduced MVO at 3 months but was not associated with a reduction in infarct size and transmurality. Thromboaspiration in Patients With High Thrombotic Burden Undergoing Primary Percutaneous (Coronary Intervention; NCT01472718).

Imaging the myocardial microcirculation post-myocardial infarction

The myocardial microcirculation provides the vital pressure control and metabolic homeostasis for normal muscle function. Microvascular dysfunction is implicated in chronic cardiac disease and can signify higher risk, but its effect in acute myocardial infarction (AMI) can be profound. Modern management of AMI is focussed entirely on timely epicardial coronary patency, but as a result can leave microcirculatory devastation in its wake. The 'no-reflow' phenomenon occurs in up to 40 % of those successfully reperfused following an ST-elevation AMI (STEMI), and reflects significant microvessel injury that at its most severe involves both microvascular obstruction (MVO) and intramyocardial haemorrhage. Myocardial contrast echocardiography and cardiac magnetic resonance imaging have both led the field in establishing MVO as the prime determinant of adverse left ventricular (LV) remodeling, LV dysfunction, heart failure and increased mortality. These imaging techniques will be essential to support future research endeavours and shift focus to the maintenance of microvascular flow in AMI.

Large coronary thrombus: A safe and effective approach using percutaneous coronary intervention after vigorous antithrombotic therapy

After percutaneous coronary intervention, high thrombotic burden is the strongest correlate for extensive microvascular obstruction, distal embolization, and the no-reflow phenomenon. It is suggested that in these cases conventional thrombectomy methods may mechanically dislodge thrombi downstream and decrease myocardial perfusion. The following report includes an alternative approach in which a coronary vessel with large thrombotic burden was treated successfully first with vigorous pharmacological antithrombotic and antiplatelet therapy followed by coronary intervention after several days.

In vivo distribution of particulate matter from coated angioplasty balloon catheters

Most catheter-based vascular medical devices today have hydrophilic lubricious coatings. This study was designed to perform a territory-based downstream analysis of end organs subsequent to angioplasty with coated balloon catheters to better understand the potential in vivo physiological consequence of coating wear materials. Coronary angioplasty was performed on swine using balloon catheters modified with two polyvinylpyrrolidone (PVP)-based coatings of similar lubricity, but different levels of particulates (5-fold) when tested in a tortuous path model. Myocardial tissues examined 28 days post-angioplasty revealed no visible particulates in the animals treated with the lower particulate catheters while 3 of 40 sections from higher particulate catheters contained amorphous foreign material, and 1 of 40 sections from tissue treated with uncoated catheters had amorphous foreign material. Non-target organs and downstream muscle revealed no particulates for any of the treatments. Histological analysis showed that the overall number of vessels with embolic foreign material was low and evidence of myocyte necrosis was rare with either of the coatings investigated in this study.

Incidence and outcomes of no-reflow phenomenon during percutaneous coronary intervention among patients with acute myocardial infarction

Previous studies describing the no-reflow phenomenon in patients with acute myocardial infarction (AMI) undergoing percutaneous coronary intervention (PCI) were largely confined to single-center studies or small registries. To better characterize the incidence, predictors, and outcomes of the no-reflow phenomenon in a large contemporary population, we analyzed patients with AMI who were undergoing PCI of native coronary artery stenoses in the CathPCI Registry from January 1, 2004 through September 5, 2008 (n = 291,380). The angiographic no-reflow phenomenon was site reported using a standardized definition. No-reflow developed in 2.3% of the patients with AMI (n = 6,553) during PCI. Older age, ST-segment elevation AMI, prolonged interval from symptom onset to admission, and cardiogenic shock were clinical variables independently associated with the development of no-reflow (p <0.001). The angiographic factors independently associated with no-reflow included longer lesion length, higher risk class C lesions, bifurcation lesions, and impaired preprocedure Thrombolysis In Myocardial Infarction flow (p <0.001). No-reflow was associated with greater in-hospital mortality (12.6% vs 3.8%, adjusted odds ratio 2.20, 95% confidence interval 1.97 to 2.47, p <0.001) and unsuccessful lesion outcome (29.7% vs 6.6%, adjusted odds ratio 4.70, 95% confidence interval 4.28 to 5.17, p <0.001) compared to patients without no-reflow. In conclusion, the development of no-reflow, although relatively uncommon during PCI for AMI, is associated with adverse clinical outcomes. Upfront strategies to reduce the incidence of no-reflow could be considered for high-risk patients to improve outcomes.

Pathophysiology of coronary thrombus formation and adverse consequences of thrombus during PCI

Atherosclerosis is a systemic vascular pathology that is preceded by endothelial dysfunction. Vascular inflammation "fuels" atherosclerosis and creates the milieu for episodes of intravascular thromboses. Thrombotic events in the coronary vasculature may lead to asymptomatic progression of atherosclerosis or could manifest as acute coronary syndromes or even sudden cardiac death. Thrombus encountered in the setting of acute coronary syndromes has been correlated with acute complications during percutaneous coronary interventions such as no-reflow, acute coronary occlusion and long term complications such as stent thrombus. This article reviews the pathophysiology of coronary thrombogenesis and explores the complications associated with thrombus during coronary interventions.