Distal Protection Improved Reperfusion and Reduced Left Ventricular Dysfunction in Patients With Acute Myocardial Infarction Who Had Angioscopically Defined Ruptured Plaque

Low Plasma Adiponectin Levels Are Associated With Vulnerable Plaque Features in Patients With Acute Coronary Syndrome: An Optical Coherence Tomography Study

BACKGROUND

Vulnerable plaques are the primary cause of acute coronary syndrome (ACS). The association between in-vivo plaque vulnerability and adiponectin levels in ACS still remains to be determined.

OBJECTIVE

The purpose of this study was to investigate the correlation between adiponectin levels and vulnerable plaque features in ACS patients.

METHODS

We enrolled 107 ACS patients admitted to our institution; 83 with Non-ST elevation ACS (NSTE-ACS) and 24 with ST-elevation myocardial infarction (STEMI). Adiponectin levels were measured in these patients. Coronary angiography and subsequent optical coherence tomography (OCT) analysis of culprit lesions were performed.

RESULTS

Adiponectin level was lower in patients with complex angiographic lesions, compared to those with non-complex lesions (7.13 ± 3.04 vs. 8.94 ± 2.84 μg/ml, P = 0.002). Adiponectin level was lower in patients with plaque rupture (PR), micro-thrombi, and thin cap fibroatheroma (TCFA), compared to those with non-vulnerable features (7.19 ± 2.95 vs 8.79 ± 3.02 μg/ml, P = 0.007 & 7.29 ± 2.97 vs 8.44 ± 3.09 μg/ml, P = 0.04 and 4.76 ± 0.65 vs 9.74 ± 2.35 μg/ml, P < 0.001 μg/ml respectively). There was a significant negative correlation between adiponectin levels and lipid rich plaque extent and maximum lipid arc (r = -0.05, P < 0.001 & r = -0.03, P = 0.03, respectively). However, a significant positive correlation was observed between adiponectin levels and fibrous cap thickness (r = 0.95, P < 0.001).

CONCLUSION

Low adiponectin levels were associated with complex angiographic lesions and vulnerable plaque features in ACS patients, where there was a significant correlation between it and PR, TCFA, and lipid rich plaque.

Comparison of angioscopy and histopathology for the evaluation of carotid plaque characteristics: an ex vivo validation study

Intravascular angioscopy is widely used for evaluating plaque characteristics through the plaque color in the coronary artery. This study evaluated whether angioscopy is capable of identifying various plaque morphologies, including necrotic core and intraplaque hemorrhage (IPH) in the carotid artery. Nine patients underwent carotid endarterectomy for carotid artery stenosis, and these specimens were imaged ex vivo by angioscopy within 6 h. An angioscopic examination of carotid plaque evaluated its color intensity as follows: white, yellow, or red. The IPH area, necrotic core area, and fibrous cap thickness was measured on histological sections at each site. A total of 7 plaques were graded as white plaques, 10 as yellow, and 8 as red by angioscopy. The IPH area and the percent area occupied by IPH were larger in red and yellow plaques than in white plaques (10.7 ± 9.3 mm², 9.4 ± 7.8 mm², and 2.2 ± 1.7 mm², respectively, P = 0.074; and 25 ± 10%, 19 ± 13%, and 7 ± 5%, respectively, P = 0.008). Furthermore, the thickness of the fibrous cap was significantly thinner in red plaques than in yellow and white plaques (128 ± 34 µm, 328 ± 136 µm, and 285 ± 102 µm, respectively, P = 0.002). The ROC analysis for predicting a presence of red plaques identified that the optimal cutoff value of fibrous cap thickness was 181 µm (area under the curve = 0.987, 100% sensitivity, 90% specificity). The prevalence of red plaques on intravascular angioscopy may represent the existence of plaques containing relatively larger necrotic core and IPH with a thin fibrous cap.

Atherosclerotic Plaque Component as a Risk Factor for Distal Embolization During Percutaneous Coronary Intervention - Pathology of Tissue Obtained by Distal Protection Device

BACKGROUND

Embolism during percutaneous coronary intervention (PCI) causes microcirculation impairment. The aim of this study was to clarify the relationship between the pathological characteristics of tissue captured by distal protection device (DPD) and amount of tissue accumulated in DPD. Methods and Results: A total of 671 consecutive lesions in PCI using DPD were examined. The amount of necrotic debris, fibrous tissue, calcified particle, platelet thrombus and organized thrombus in the DPD baskets was histologically evaluated. The DPD tissue amount was assessed semi-quantitatively, and the relationship between the captured DPD tissue characteristics and tissue amount was investigated. On pathology, 40.7% of the lesions had necrotic debris, 41.4% had fibrous tissue, and 18.0% had calcified particle. The prevalence of lesions in patients with acute coronary syndrome (ACS) was 62.1%. Tissue amount score distribution was as follows: score 1 (tissue invisible), 3.9%; score 2 (tissue clinging to the basket), 52.0%; score 3 (tissue accumulated at the bottom of the basket), 38.5%; and score 4 (tissue accumulated in more than half of the basket), 5.7%. On multivariate analysis, necrotic debris and fibrous tissue were associated with greater tissue amount as well as clinical presentation of ACS.

CONCLUSIONS

The presence of atherosclerotic plaque component, such as necrotic debris and fibrous tissue, might be a risk for distal embolism during PCI.

Predictors of angiographically visible distal embolization in STEMI

BACKGROUND

Distal embolization during primary percutaneous coronary intervention (p-PCI) in the treatment of ST-segment elevation myocardial infarction (STEMI) is associated with a poor prognosis. In this situation, thrombectomy is performed to prevent distal embolization and to restore myocardial reperfusion. The aim of our study was to determine angiographic predictors of angiographically visible distal embolization (AVDE) in patients with STEMI treated by p‑PCI with thrombectomy.

PATIENTS AND METHODS

This prospective study included all consecutive patients who underwent p‑PCI with thrombectomy for STEMI at our institution between October 2011 and December 2014 AVDE was defined as a distal filling defect with an abrupt cut-off in one of the peripheral coronary branches of the infarct-related artery, distal to the angioplasty site. Thrombectomy was considered positive when it removed thrombi, and successful when it improved coronary flow.

RESULTS

Among the 346 patients included, 59 (17%) developed AVDE during p‑PCI. In multivariate analysis, the infarct-related right coronary artery (OR: 2.48, 95% CI: 1.36-4.52; p = 0.003) and a culprit lesion diameter of >3 mm (OR : 1.90, 95% CI: 1.01-3.56; p = 0.048) were identified as independent factors associated with AVDE during p‑PCI with thrombectomy for STEMI. The success of thrombectomy and the Syntax score were not associated with AVDE.

CONCLUSION

AVDE complicating p‑PCI with thrombectomy in STEMI is frequent (17%) and a successful thrombectomy does not rule out AVDE.

The utility of total lipid core burden index/maximal lipid core burden index ratio within the culprit plaque to predict filter-no reflow: insight from near-infrared spectroscopy with intravascular ultrasound

Filter-no reflow (FNR) is a phenomenon wherein flow improves after the retrieve of distal protection. Near-infrared spectroscopy with intravascular ultrasound (NIRS-IVUS) enables lipid detection. We evaluated the predictors of FNR during PCI using NIRS-IVUS. Thirty-two patients who underwent PCI using the Filtrap® for acute coronary syndrome (ACS) were enrolled. The culprit plaque (CP) was observed using NIRS-IVUS. Total lipid-core burden index (T-LCBI) and maximal LCBI over any 4-mm segment (max-LCBI4mm) within CP were evaluated. T-LCBI/max-LCBI4mm ratio within CP was calculated as an index of the extent of longitudinal lipid expansion. The attenuation grade (AG) and remodeling index (RI) in CP were analyzed. AG was scored based on the extent of attenuation occupying the number of quadrants. The patients were divided into FNR group (N = 8) and no-FNR group (N = 24). AG was significantly higher in FNR group than in no-FNR group (1.6 ± 0.6 vs. 0.9 ± 0.42, p = 0.01). RI in FNR group tended to be greater than in no-FNR group. T-LCBI/max-LCBI4mm ratio within the culprit plaque was significantly higher in FNR group than in no-FNR group (0.50 ± 0.10 vs. 0.33 ± 0.13, p < 0.01). In multivariate logistic regression analysis, AG > 1.04 (odds ratio [OR] 18.4, 95% confidence interval [CI] 1.5-215.7, p = 0.02) and T-LCBI/max-LCBI4mm ratio > 0.42 (OR 14.4, 95% CI 1.2-176.8, p = 0.03) were independent predictors for the occurrence of FNR. The use of T-LCBI/max-LCBI4mm ratio within CP might be an effective marker to predict FNR during PCI in patients with ACS.

The combination assessment of lipid pool and thrombus by optical coherence tomography can predict the filter no-reflow in primary PCI for ST elevated myocardial infarction

The usefulness of distal protection devices is still controversial. Moreover, there is no report on thrombus evaluation by using optical coherence tomography (OCT) for determining whether to use a distal protection device. The aim of the present study was to investigate the predictor of filter no-reflow (FNR) by using OCT in primary percutaneous coronary intervention (PCI) for ST-elevated acute myocardial infarction (STEMI).We performed preinterventional OCT in 25 patients with STEMI who were undergoing primary PCI with Filtrap. FNR was defined as coronary flow decreasing to TIMI flow grade 0 after mechanical dilatation.FNR was observed in 13 cases (52%). In the comparisons between cases with or without the FNR, the stent length, lipid pool length, lipid pool + thrombus length, and lipid pool + thrombus index showed significant differences. In multivariate analysis, lipid pool + thrombus length was the only independent predictor of FNR (OR 1.438, 95% CI 1.001 - 2.064, P < .05). The optimal cut-off value of lipid pool + thrombus length for predicting FNR was 13.1 mm (AUC = 0.840, sensitivity 76.9%, specificity 75.0%). Moreover, when adding the evaluation of thrombus length to that of lipid pool length, the prediction accuracy of FNR further increased (IDI 0.14: 0.019-0.25, P = .023).The longitudinal length of the lipid pool plus thrombus was an independent predictor of FNR and the prediction accuracy improved by adding the thrombus to the lipid pool. These results might be useful for making intraoperative judgment about whether filter devices should be applied in primary PCI for STEMI.

Coronary plaque morphology on multi-modality imagining and periprocedural myocardial infarction after percutaneous coronary intervention

Percutaneous coronary intervention (PCI) may be complicated by periprocedural myocardial infarction (PMI) as manifested by elevated cardiac biomarkers such as creatine kinase (CK)-MB or troponin T. The occurrence of PMI has been shown to be associated with worse short- and long-term clinical outcome. However, recent studies suggest that PMI defined by biomarker levels alone is a marker of atherosclerosis burden and procedural complexity but in most cases does not have independent prognostic significance. Diagnostic multi-modality imaging such as intravascular ultrasound, optical coherence tomography, coronary angioscopy, near-infrared spectroscopy, multidetector computed tomography, and magnetic resonance imaging can be used to closely investigate the atherosclerotic lesion in order to detect morphological markers of unstable and vulnerable plaques in the patients undergoing PCI. With the improvement of technical aspects of multimodality coronary imaging, clinical practice and research are increasingly shifting toward defining the clinical implication of plaque morphology and patients outcomes. There were numerous published data regarding the relationship between pre-PCI lesion subsets on multi-modality imaging and post-PCI biomarker levels. In this review, we discuss the relationship between coronary plaque morphology estimated by invasive or noninvasive coronary imaging and the occurrence of PMI. Furthermore, this review underlies that the value of the multimodality coronary imaging approach will become the gold standard for invasive or noninvasive prediction of PMI in clinical practice.

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Periprocedural myocardial infarction (PMI) has been shown to be associated with worse short- and long-term clinical outcome.

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Clinical practice and research are increasingly shifting toward the plaque morphology and patients outcomes.

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This review discusses the relationship between plaque morphology estimated by coronary imaging and the occurrence of PMI.

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This review underlies the value of the multimodality coronary imaging approach for prediction of PMI in clinical practice.

Manual Thrombus Aspiration and the Improved Survival of Patients With Unstable Angina Pectoris Treated With Percutaneous Coronary Intervention (30 Months Follow-Up)

The clinical effect of intracoronary thrombus aspiration during percutaneous coronary intervention in patients with unstable angina pectoris is unknown. In this study, we aimed to assess how thrombus aspiration during percutaneous coronary intervention affects in-hospital and 30-month mortality and complications in patients with unstable angina pectoris.We undertook an observational cohort study of 645 consecutive unstable angina pectoris patients who had performed percutaneous coronary intervention from February 2011 to March 2013. Before intervention, 159 patients who had culprit lesion with thrombus were randomly assigned to group 1 (thrombus aspiration group) and group 2 (stand-alone percutaneous coronary intervention group). All patients were followed-up 30 months until August 2015.Thrombus aspiration was performed in 64 patients (46%) whose cardiac markers (ie, creatinine kinase [CK-MB] mass and troponin T) were significantly lower after percutaneous coronary intervention than in those of group 2 (CK-MB mass: 3.80 ± 1.11 vs 4.23 ± 0.89, P = 0.012; troponin T: 0.012 ± 0.014 vs 0.018 ± 0.008, P = 0.002). Left ventricular ejection fraction at 6, 12, and 24 months postintervention was significantly higher in the group 1. During a mean follow-up period of 28.87 ± 6.28 months, mortality rates were 6.3% in the group 1 versus 12.9% in the group 2. Thrombus aspiration was also associated with significantly less long-term mortality in unstable angina pectoris patients (adjusted HR: 4.61, 95% CI: 1.16-18.21, P = 0.029).Thrombus aspiration in the context of unstable angina pectoris is associated with a limited elevation in cardiac enzymes during intervention that minimises microembolization and significantly improves both of epicardial flow and myocardial perfusion, as shown by angiographic TIMI flow grade and frame count. Thrombus aspiration during percutaneous coronary intervention in unstable angina pectoris patients has better survival over a 30-month follow-up period.

Optical coherence tomography features of angiographic complex and smooth lesions in acute coronary syndromes

Plaque rupture (PR) and superimposed thrombosis have been shown as the most frequent underlying substrate in acute coronary syndromes (ACS). Coronary angiography is a luminogram not able to define in vivo features of the culprit plaques. The aim of the study was to use optical coherence tomography (OCT) to investigate the pathology underlying complex (CL) and non-complex angiographic lesions (NCL). We retrospectively enrolled 107 ACS patients admitted to our institution; 83 with non-ST elevation ACS (NSTE-ACS) and 24 with ST-elevation myocardial infarction. Coronary angiography was performed and culprit lesions were classified according to Ambrose criteria into NCL (n = 47) and CL (n = 60). OCT imaging was then performed to better identify plaque morphology; either PR or intact fibrous cap, the presence of superimposed thrombosis, lipid rich plaque, and thin cap fibroatheroma (TCFA). OCT analysis showed that 58 lesions (54.2%) were classified as PR and 48 lesions (44.9%) were associated with thrombi. Lipid rich plaques were identified in 62 lesions (57.9%). PR, intracoronary thrombi, lipid rich plaques and TCFA were more frequent in CL compared with NCL (71.7 vs 31.9%, 63.3 vs 21.3%, 71.7 vs 40.4% and 46.7 vs 21.3% respectively), but PR with superimposed thrombus may be also detected in NCL. OCT demonstrates PR and thrombosis in the majority of ACS patients presenting with CL. However, one-third of NCL show PR by OCT, suggesting that additional intracoronary imaging by OCT may better identify the underlying mechanism of coronary instability than coronary angiography alone.

Slow-flow phenomenon after elective percutaneous coronary intervention of computed tomography-detected vulnerable coronary lesion

No-reflow or slow-flow phenomenon is one of the serious complications of percutaneous coronary interventions (PCI) in acute myocardial infarction, as well as during elective procedures, and is an independent predictor of myocardial infarction, and in-hospital and long-term mortality. We present a case of an elective PCI of native coronary artery lesion that was assessed to be vulnerable based on coronary computed tomography angiography, complicated with slow-flow phenomenon.

Association of target lesion characteristics evaluated by coronary computed tomography angiography and plaque debris distal embolization during percutaneous coronary intervention

BACKGROUND

The slow-flow or no re-flow phenomenon has been associated with distal embolization, especially of plaque debris, and with unfavorable clinical outcomes. Therefore, we examined the association between the coronary computed tomography angiography (CCTA) findings of the target lesion and distal embolization during percutaneous coronary intervention (PCI). METHODS AND RESULTS: Consecutive patients (n=55: 18 unstable angina, 19 stable effort angina, 18 silent ischemia) who underwent PCI with a filter-type distal protection device after evaluation of the target lesion by CCTA were analyzed. CCTA examined low-attenuation plaque (LAP), positive remodeling (PR), and ring-like enhancement of the target lesion. Distal embolization of thrombus and plaque debris was evaluated by pathological examination of material collected in the filter.Any distal embolization and distal embolization of plaque debris were respectively detected in 75% and 0% of patients with LAP or PR alone, in 95% and 17% of patients with both LAP and PR, and in 100% and 27% of patients with all of LAP, PR and ring-like enhancement. The sensitivity and specificity to predict plaque debris embolization by having both findings of LAP and PR was 100% and 46%, respectively.

CONCLUSIONS

The CCTA findings of the target lesion were associated with distal embolization and were very sensitive for predicting plaque debris embolization.

Difference of ruptured plaque morphology between asymptomatic coronary artery disease and non-ST elevation acute coronary syndrome patients: an optical coherence tomography study

BACKGROUND

Autopsy studies have reported that rupture of a thin-cap fibroatheroma and subsequent thrombus formation is the major mechanism leading to acute coronary syndrome (ACS). However, it is not clear why only some plaque ruptures lead to ACS. Optical coherence tomography (OCT) is a high-resolution imaging modality which is capable of investigating detailed coronary plaque morphology in vivo. The objective of this study was to determine whether ruptured plaque morphology assessed by OCT differs between asymptomatic coronary artery disease (CAD) and non-ST elevation acute coronary syndrome (NSTEACS).

METHODS

We examined ruptured plaque morphology using OCT in 80 patients, 33 with asymptomatic CAD and 47 with NSTEACS.

RESULTS

The frequency of lipid-rich plaque and intracoronary thrombus was significantly lower in asymptomatic CAD than in NSTEACS (61% vs. 85%, p = 0.013 and 9% vs. 83%, p < 0.001, respectively). Although maximal ruptured cavity cross-sectional area (CSA) was similar in both groups, lumen area at the rupture site and minimal lumen area were significantly larger in asymptomatic CAD than in NSTEACS (3.78 ± 1.50 mm(2) vs. 2.70 ± 1.55 mm(2), p = 0.003 and 2.75 ± 0.99 mm(2) vs. 1.72 ± 0.90 mm(2), p < 0.001, respectively).

CONCLUSIONS

OCT revealed that the morphology of ruptured plaques differs between asymptomatic CAD and NSTEACS in terms of lumen area and the frequency of lipid-rich plaques and thrombi. These morphological features may be associated with the clinical presentation of CAD.

Detection of yellow plaque by near-infrared spectroscopy - Comparison with coronary angioscopy in a case of no-flow phenomenon during coronary intervention

Yellow plaques detected by coronary angioscopy have been regarded as vulnerable plaques and associated with distal embolization or slow/no-flow phenomenon during coronary intervention. This is the first report that compared the findings of angioscopy and near-infrared spectroscopy (NIRS) in a patient who suffered no-flow phenomenon during coronary intervention. A 41-year-old male patient with silent myocardial ischemia received coronary intervention. Coronary angiogram revealed diffuse stenosis in the distal right coronary artery. Target lesion was examined by NIRS and angioscopy. NIRS can detect lipid core plaque, which is presented as an yellow area in contrast to the normal red area. Target segment was filled with lipid core plaques. On the other hand, angioscopy revealed a ruptured yellow plaque with a thrombus in the target segment. The distribution of yellow plaques detected by angioscopy appeared well corresponded to the yellow areas detected by NIRS. After the insertion of filter-type distal protection device, balloon pre-dilatation and stent implantation were performed. Then, no-flow phenomenon occurred. Coronary flow was finally recovered in the protected vessel but was still disturbed in the non-protected vessel. The filter was filled with much plaque debris. The correlation between the yellow area detected by NIRS and the yellow plaques detected by angioscopy appeared very well. <Learning objective: The correlation between the yellow area detected by near-infrared spectroscopy (NIRS) and the yellow plaques detected by angioscopy appeared very well. As well as yellow plaque detected by angioscopy, lipid core plaque as shown in yellow area by NIRS may also be associated with future event of acute coronary syndrome and distal embolization during coronary intervention.>.

Prevention of no-reflow phenomenon in culprit lesions involving a large side branch

No-reflow/slow-flow phenomenon (NF) is a poor prognostic factor in patients undergoing percutaneous coronary intervention. Distal protection devices (DPDs) prevent myocardial injury due to microembolic debris. When the target lesion involves a large side branch, DPDs can only protect the main vessel but not the side branch. In the present report, we describe the use of a two-step deflation in kissing-balloon technique for preventing NF in 4 patients (M/F = 4/0, 65 ± 6 years) in which the culprit lesions with NF risk involved a bifurcation. The procedures were uneventful and the 4 patients were discharged ≤24 h without ECG change and elevation of serum level of creatine kinase. The sequential deflation of kissing-balloon technique may constitute a possible solution for the NF related with the side branch on bifurcation lesions.

Comparison of the reperfusion efficacy of thrombus aspiration with and without distal protection during primary percutaneous coronary intervention in patients with acute ST-segment elevation myocardial infarction

We evaluated a hypothesis that thrombus aspiration with distal protection is superior to simple thrombus aspiration in patients treated with primary percutaneous coronary intervention (PCI). A total of 176 consecutive patients with ST-segment elevation myocardial infarction were enrolled in this study and assigned to either the thrombus aspiration group (A, n = 104) or the thrombus aspiration with distal protection group using a filter device system (A + DP, n = 72). We compared the angiographic reperfusion grade, left ventricular (LV) function, and clinical outcomes between the 2 groups. There were no significant differences in age, gender distribution, the onset-to-reperfusion time, the peak levels of creatine kinase, or 6-month mortality between the 2 groups. The rate of achieving a Thrombolysis In Myocardial Infarction flow grade of 3 and a myocardial blush grade of 3 was higher in the A + DP group than in the A group. Among the patients who underwent follow-up catheterization 6 months after PCI (A, n = 62; A + DP, n = 52), there were no significant differences in the LV end-diastolic volume index, LV end-systolic volume index, or LV ejection fraction between the 2 groups at the time of PCI or 6 months after PCI. In conclusion, thrombus aspiration with distal protection may be more effective in initially restoring the coronary blood flow than thrombus aspiration alone, although it may not be superior to thrombus aspiration in preventing LV remodeling or preserving the LV function in patients with ST-segment elevation myocardial infarction.

Ruptured plaque and large plaque burden are risks of distal embolisation during percutaneous coronary intervention: evaluation by angioscopy and virtual histology intravascular ultrasound imaging

AIMS

Slow flow and no flow phenomena have been associated with distal embolisation, especially of plaque debris, and with unfavourable clinical outcomes. However, patients at high risk of distal embolisation for whom distal protection might be beneficial have not been adequately identified. We examined the frequency of distal embolisation and its predicting factors, including both ACS and non-ACS patients.

METHODS AND RESULTS

Consecutive patients (n=98) with or without ACS who had received PCI with a filter-type distal protection device and successful angioscopic and VH-IVUS examination were prospectively enrolled. The presence of yellow plaque and plaque rupture was evaluated by angioscopy. Tissue classification and plaque burden was evaluated by VH-IVUS. Distal embolisation was evaluated by pathological examination of material collected in the filter. Distal embolisation of plaque debris was more frequently detected in patients with ACS (48% vs. 25%, p=0.02), in those with ruptured plaque (86% vs. 13%, p<0.001), in those with large (>75%) plaque burden (50% vs. 23%, p=0.006), and in those with grade 2/3 yellow plaque (52% vs. 7%, p<0.001), as compared to those without it.

CONCLUSIONS

The presence of ruptured yellow plaque and of large plaque burden, rather than the setting of ACS, was highly predictive of distal embolisation of plaque debris.

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

OBJECTIVES

This study sought to investigate the association between pathological characteristics of aspirated intracoronary thrombi and the incidence of angiographically visible distal embolization (AVDE) during primary percutaneous coronary intervention (p-PCI) in patients with ST-segment elevation myocardial infarction (STEMI) treated with thrombus aspiration.

BACKGROUND

AVDE of atherosclerotic and thrombotic material has been shown to impair myocardial perfusion and contribute to poor clinical outcome in patients with STEMI. Recent studies have shown that thrombus composition and size are associated with the incidence of AVDE.

METHODS

Aspirated thrombi from 164 STEMI patients within 12 h of symptom onset were investigated immunohistochemically using antibodies against platelets, erythrocytes, and inflammatory cells.

RESULTS

The angiographic results showed that AVDE during p-PCI occurred in 22 (13.4%) patients. Pathological analysis revealed that thrombi from patients with AVDE had a greater erythrocyte-positive area (60 ± 15% vs. 43 ± 21%, p < 0.0005) and more myeloperoxidase-positive cells (943 ± 324 cells/mm(2) vs. 592 ± 419 cells/mm(2), p < 0.0005) than those from patients without AVDE. Thrombus size, quantified as the thrombus surface area, was positively correlated with the erythrocyte component (r = 0.362, p < 0.0001). Moreover, multivariate logistic analysis demonstrated that erythrocyte-positive area in the thrombi, glucose levels on admission, larger vessel diameter (≥ 3.5 mm), and pre-balloon dilation were independent predictors of the incidence of AVDE.

CONCLUSIONS

This study demonstrated that the erythrocyte-rich component of aspirated thrombi may be associated with the incidence of AVDE during p-PCI in patients with STEMI.

No-Reflow Phenomenon

No-reflow is responsible for 40% of the primary percutaneous coronary intervention without complete myocardial reperfusion despite successful reopening of the infarct-related artery. This review describes the main pathophysiological mechanisms of no-reflow, its clinical manifestation, including the strong association with increased in-hospital mortality, malignant arrhythmias, and cardiac failure as well as the diagnostic methods. The latter ranges from simple angiographic thrombolysis in myocardial infarction grade score to more complex angiographic indexes, imaging techniques such as myocardial contrast echo or cardiac magnetic resonance, and surrogate clinical end points such as ST-segment resolution. This review also summarizes the strategies of prevention and treatment of no-reflow, considering the most recent studies results regarding medical therapy and devices.

Intense yellow culprit plaque coloration is closely associated with troponin-T elevation and flow complications following elective coronary stenting

AIM

The elevation of troponin-T (TnT) and occurrence of transient slow-flow phenomena have been recognized as procedure-related myocardial injuries. Little is known about the characteristics of high-risk plaque resulting in myocardial injury after coronary stenting.

METHODS

The culprit plaques in 42 consecutive patients with stable angina undergoing elective coronary stenting were observed by angioscopy. The plaque color upon angioscopic examination was classified as either intense yellow or not yellow. Slow flow was defined as < TIMI grade 3 flow during the procedure. The TnT levels were measured 8, 16, and 24 hours after stenting, and myocardial injury was defined as TnT ≥ 0.03 ng/mL at any time point.

RESULTS

Twenty-four patients (57%) had intense yellow plaques and myocardial injury occurred in 22 patients (52%). The frequency of intense yellow plaque was significantly higher in the patients with myocardial injury than in those without myocardial injury (91% vs. 20%, p < 0.001). Transient slow flow occurred frequently in patients with myocardial injury than in those without myocardial injury (23% vs. 0%, p = 0.049). All patients with transient slow flow had intense yellow plaques at the culprit lesions.

CONCLUSIONS

Intense yellow culprit plaque coloration was closely associated with TnT elevation and flow complications following elective coronary stenting. Angioscopically-observed intense yellow coloration may therefore predict high-risk plaque for peri-procedural myocardial injury.

Management of the no-reflow phenomenon

The lack of reperfusion of myocardium after prolonged ischaemia that may occur despite opening of the infarct-related artery is termed "no reflow". No reflow or slow flow occurs in 3-4% of all percutaneous coronary interventions, and is most common after emergency revascularization for acute myocardial infarction. In this setting no reflow is reported to occur in 30% to 40% of interventions when defined by myocardial perfusion techniques such as myocardial contrast echocardiography. No reflow is clinically important as it is independently associated with increased occurrence of malignant arrhythmias, cardiac failure, as well as in-hospital and long-term mortality. Previously the no-reflow phenomenon has been difficult to treat effectively, but recent advances in the understanding of the pathophysiology of no reflow have led to several novel treatment strategies. These include prophylactic use of vasodilator therapies, mechanical devices, ischaemic postconditioning and potent platelet inhibitors. As no reflow is a multifactorial process, a combination of these treatments is more likely to be effective than any of these alone. In this review we discuss the pathophysiology of no reflow and present the numerous recent advances in therapy for this important clinical problem.

Angioscopic and virtual histology intravascular ultrasound characteristics of culprit lesion morphology underlying coronary artery thrombosis

Although rupture of vulnerable plaque with subsequent thrombosis is the most common mechanism of acute coronary syndromes, a significant percentage of patients with acute coronary syndrome may not have plaque rupture. We used angioscopy and virtual histology intravascular ultrasound (VH-IVUS) to investigate the underlying morphology of coronary thrombosis. We correlated the angioscopic diagnosis of coronary thrombosis in 42 lesions (37 patients) with gray-scale and VH-IVUS findings of the underlying plaque. By angioscopy plaque rupture was present in 19 thrombotic lesions (45.2%), whereas 23 (54.8%) had no rupture. VH-IVUS findings comparing thrombotic lesions with to those without angioscopic plaque rupture were remarkably similar except that angioscopic nonruptures tended to have more necrotic core (NC) at the minimum lumen area site (22.2 ± 12.5% vs 16.3 ± 9.3%, p=0.09) and at the maximum NC site (32.7 ± 12.8% vs 25.0 ± 12.1%, p=0.053) compared to angioscopic ruptures. Furthermore, among 19 lesions with angioscopic plaque rupture, there were 11 VH thin-cap fibroatheromas (TCFAs; 57.9%); among 23 lesions without angioscopic rupture, there were 17 VH-TCFAs (73.9%, p=0.22). In conclusion, the similarity of VH-IVUS plaque composition (percentage of NC and percentage of VH-TCFA) in lesions with or without angioscopic plaque rupture suggest a spectrum of underlying morphologies to explain thrombosis in the absence of a ruptured plaque including classic erosions, small (and undetectable) plaque ruptures, and potentially unruptured TCFAs with superimposed thrombosis.

Coronary angioscopy: current topics and future direction

Disruption of vulnerable plaque and following thrombus formation are considered the main cause of acute coronary syndrome (ACS). Intracoronary angioscopy is an endoscopic technology that allows direct visualization of the coronary artery lumen and provides detailed information regarding plaque morphology in patients with coronary artery disease. The color and morphology of coronary plaque under angioscopy observation are proposed to be determinants for plaque stability. Angioscopically yellow plaque represents a thin-cap fibroatheroma, and is associated with a higher incidence of disruption and thrombus formation, and may be associated with future acute coronary syndromes. To circumvent the subjectivity of color interpretation, various quantitative methods have been proposed for identifying vulnerable plaques. Superior to other coronary imaging techniques such as VH IVUS and optical coherence tomography, angioscopy has impressively high sensitivity and specificity in detection of intraluminal thrombus. Angioscopy can also be used as an adjunctive technique during catheter intervention by directly visualizing the thrombus, stent struts and proliferating neointima. The time course and pattern of neointima coverage, as seen by angioscopy, various among different stent systems. Angioscopic assessment of serial changes after stent implantation may have potential benefits on patient's management after coronary stenting.

Acute coronary syndrome: insight from angioscopy

Although the concept of vulnerable plaque has become common, it is still impossible to predict effectively the onset of acute coronary syndrome (ACS). Thin-cap fibroatheroma (TCFA) is regarded as vulnerable from pathological studies and various diagnostic tools have tried to detect TCFA clinically but failed to predict ACS. Because there are so many silent plaque ruptures detected, it is supposed that many vulnerable plaques might have ruptured but not caused ACS. Some factor(s) other than the rupture of vulnerable plaque is required for the onset of ACS. "Vulnerable blood" may be one of them. The thrombogenic potential of blood (ie, vulnerable blood) may play an important and determinant role in the onset of ACS, the process of which will be discussed from the angioscopic point of view.

Coronary microembolization: from bedside to bench and back to bedside

Coronary microembolization from the erosion or rupture of a vulnerable atherosclerotic plaque occurs spontaneously in acute coronary syndromes and iatrogenically during percutaneous coronary interventions. Typical consequences of coronary microembolization are microinfarcts with an inflammatory response, contractile dysfunction, and reduced coronary reserve. Apart from transient elevations of creatine kinase and troponin, microemboli can be visualized by intracoronary Doppler and the resulting microinfarcts by late-enhancement nuclear magnetic resonance. Statins, antiplatelet agents, and coronary vasodilators protect against microembolization and microinfarction when started before percutaneous coronary interventions. Distal protection devices can retrieve atherothrombotic debris and prevent its embolization into the microcirculation, but their effect on clinical outcome has been disappointing so far, except for saphenous vein bypass grafts. Devices for aspiration of thrombi and thrombus-derived vasoconstrictor, thrombogenic, and inflammatory substances, however, reduce thrombus burden, improve perfusion, and provide protection in patients with acute myocardial infarction.

The results of a new distal protection method in intervention for chronic total occlusion of the superficial femoral artery

Aims. To determine the efficacy of a new distal protection method in SFA CTO interventions. Methods and Results. From June 2003 to February 2009, ninety-two consecutive, chronic total occlusions of superficial femoral arteries were treated with catheter-based intervention using a bidirectional approach. Nine of these cases were managed with our original, distal protection method, based on symptoms, angiographic images, wire resistance, and intravascular ultrasound images. The average age was 73 years; eight patients were male. The mean occlusion length was 17.1 cm. A distal protection balloon was inserted from the retrograde sheath in the popliteal artery and placed distal to the occluded lesion after successful wire crossing. Lesion dilatation with a balloon was performed antegradely and debris was removed by 6Fr. guiding catheter. Debris was retrieved from all lesions, consisting mainly of thrombus. Where we decided not to use the distal protection method, there was no distal thromboembolism. Conclusion. In SFA-CTO intervention, the risk of distal embolization is 10%, which can be anticipated and eliminated by the distal protection method.

Systematic analysis of functional and structural changes after coronary microembolization: a cardiac magnetic resonance imaging study

OBJECTIVES

Our study aimed to detect the morphological und functional effects of coronary microembolization (ME) in vivo by cardiac magnetic resonance (CMR) imaging in an established experimental animal model.

BACKGROUND

Post-mortem morphological alterations of coronary ME include perifocal inflammatory edema and focal microinfarcts. Clinically, the detection of ME after successful coronary interventions identifies a population with a worse long-term prognosis.

METHODS

In 18 minipigs, ME was performed by intracoronary infusion of microspheres followed by repetitive in vivo imaging on a 1.5-T MR system from 30 min to 8 h after ME. Additionally, corresponding ex vivo CMR imaging and histomorphology were performed.

RESULTS

Cine CMR imaging demonstrated a time-dependent increase of wall motion abnormalities from 9 of 18 animals after 30 min to all animals after 8 h (0.5 h, 50%; 2 h, 78%; 4 h, 75%; 8 h, 100%). Whereas T2 images were negative 30 min after ME, 4 of 18 animals showed myocardial edema at follow-up (0.5 h, 0%; 2 h, 6%; 4 h, 25%; 8 h, 17%). In vivo late gadolinium enhancement (LGE) was observed in none of the animals after 30 min, but in 33%, 50%, and 83% of animals at 2 h, 4 h, and 8 h, respectively, after ME. Ex vivo CMR imaging showed patchy areas of LGE in all but 1 animal (2 h, 83%; 4 h, 100%; 8 h, 100%). A significant correlation was seen between the maximum troponin I level and LGE in vivo (r = 0.63) and the spatial extent of ex vivo LGE (r = 0.76).

CONCLUSIONS

Our results show that in vivo contrast-enhanced CMR imaging allows us to detect functional and structural myocardial changes after ME with a high sensitivity. Ex vivo, the pattern of LGE of high-resolution, contrast-enhanced CMR imaging is different from the well-known pattern of LGE in compact myocardial damage. Thus, improvements in spatial resolution are thought to be necessary to improve its ability to visualize ME-induced structural alterations even in vivo.