No-reflow following dilatation of a coronary lesion with a large lipid core

Evaluation of Variable Thin-Cap Fibroatheroma Definitions and Association of Virtual Histology-Intravascular Ultrasound Findings With Cavity Rupture Size

The accepted definition of virtual histology intravascular ultrasound (IVUS-VH) thin-cap fibroatheroma (TCFA) is only a modest predictor of plaque rupture (PR). We sought to determine the relation between IVUS-VH findings and culprit lesions with PR using computational analysis. A total of 80 culprit lesions from 80 patients with stable angina (n = 37), unstable angina (n = 20), and myocardial infarction (n = 23) were divided into those with (n = 15) and without PR (n = 65). By use of automated computational analysis, the standard IVUS-VH TCFA criterion and 124 additional criteria were compared. The standard TCFA definition demonstrated modest ability to discriminate lesions with and without PR (sensitivity 87%, specificity 37%, PPV 0.24, and NPV 0.92). Of 124 additional IVUS-VH TCFA definitions, only 2 improved the discriminative ability even modestly. However, a positive correlation was demonstrated between cavity size and necrotic core percentage (r = 0.78, p <0.01) and a negative correlation with percentage of fibrous tissue (r = -0.81, p <0.01). In conclusion, IVUS-VH criteria were only modestly associated with PR, without significant improvement by varying IVUS-VH TCFA features, but IVUS-VH features of ruptured plaques were strongly correlated with cavity size.

Association between local interleukin-6 levels and slow flow/microvascular dysfunction

We aimed to investigate the association between local interleukin-6 (IL-6) levels at the infarct-related artery and the risk of slow flow/microvascular dysfunction after PCI in ST-elevation acute myocardial infarction (AMI) patients treated by successful primary PCI. 56 eligible ST-elevation AMI patients (34 male/22 female, mean age: 63.5 ± 10.3 years), undergoing successful primary PCI, were included in the current study. Blood samples were obtained from the extraction catheter placed distal to the lesion before PCI. Plasma IL-6 levels were determined by immunoassay method. Slow flow/microvascular dysfunction was observed in 21 patients (37.5%). Using multiple logistic regression analysis, local IL-6 levels (OR 1.592, CI 1.135-2.268; P = 0.007) were found to be a significant risk factor of slow flow/microvascular dysfunction together with diabetes mellitus (OR = 8.065, CI 1.244-52.632; P = 0.029) and thrombus score (OR = 12.500, CI 1.100-142.857; P = 0.042). Receiver operating characteristic (ROC) curve analysis revealed that local IL-6 (ROC area 0.824, OR 1.704, CI 1.274-2.281, P < 0.001; optimal threshold ≥11.3 pg/ml) had a predictive value of slow flow/microvascular dysfunction with sensitivity of 73% and specificity of 71%. Our study indicated that inflammatory response as presented by local IL-6 levels was associated with slow flow/microvascular dysfunction in patients with ST-elevation AMI after successful primary PCI.

Microemboli and microvascular obstruction in acute coronary thrombosis and sudden coronary death: relation to epicardial plaque histopathology

OBJECTIVES

This study examined myocardial microvascular emboli and obstruction, and related these to plaque in the epicardial coronary arteries supplying the affected microvessels.

BACKGROUND

Epicardial coronary thrombosis often causes microemboli and microvascular obstruction. The consequences of myocardial microvessel obstruction and myocyte necrosis are substantial, yet histopathologic characterization of epicardial coronary artery plaque has been incompletely characterized. This study examined myocardial microvascular emboli, and related these to plaque in the coronary arteries supplying the microvessels.

METHODS

Hearts from sudden coronary death patients underwent examination for coronary artery plaque type and cardiac microemboli.

RESULTS

Forty-four hearts were available for evaluation. Mean age at death was 51 +/- 15 years. Coronary artery analysis found 26 plaque ruptures and 21 erosions, and a mean of 4.5 microemboli per heart. Microemboli and microvascular obstruction occurred most often from eroded plaques. Microemboli and occluded intramyocardial vessels were most common in the left anterior descending coronary artery, and all vessels contained fibrin and platelets. Mean stenoses of the culprit lesion was 74% in those with emboli and 75% in those without (p = NS). Intramyocardial microemboli were more common in plaque erosion than in rupture. Microvessels <200 mum were most often those that were occluded.

CONCLUSIONS

Microemboli and microvascular obstruction are common in patients dying of acute coronary thrombosis. Plaque erosion is more likely to cause emboli in vessels <200 mum. These emboli and microvessel obstruction have a prominent clinical role since myonecrosis is often associated with these findings.

Comparison of the Effects of a Distal Embolic Protection Device and an Aspiration Catheter During Percutaneous Coronary Intervention in Patients With Acute Myocardial Infarction

BACKGROUND

The beneficial effect of percutaneous coronary intervention (PCI) using stents for acute myocardial infarction (AMI) has already been demonstrated, but there is the problem that mechanical microvascular occlusion can occur because of thrombus/atheroma embolization when the PCI was performed. The aim of the present study was to retrospectively test and compare the effects of an aspiration catheter or distal embolic protection with a distal occlusion balloon catheter to prevent peripheral vascular embolization.

METHODS AND RESULTS

The subjects consisted of 135 patients who underwent PCI with stenting within 12 h of the onset of chest pain caused by their first AMI. They were divided into 2 groups; the aspiration group, consisted of 81 consecutively seen patients who underwent aspiration catheter treatment between January 2001 and May 2002, and the distal protection group was the next group of 54 consecutively seen patients treated with a distal protection device between June 2002 and February 2003. The results were as follows. Thrombolysis in Myocardial Infarction (TIMI) score of 3 was obtained significantly more frequently in the distal protection group (94.4%) than in the aspiration group (79.0%). Additionally, the intensity of the cardiac muscle stain (blush score) was evaluated on coronary angiography and the rate of cases showing a blush score of 3, which indicates favorable blood perfusion at the tissue level, in the distal protection group (56.6%) was significantly greater than in the aspiration group (33.3%, p<0.01). The time to peak blood concentration of creatinine kinase was also significantly shorter in the distal protection group.

CONCLUSIONS

The distal embolism protection method is superior to the aspiration method for prevention of embolization after PCI with stenting for AMI, in terms of tissue level reperfusion in myocardial recanalization therapy.

Characteristics of the Pathological Images of Coronary Artery Thrombi According to the Infarct-Related Coronary Artery in Acute Myocardial Infarction

BACKGROUND

Unstable plaque and coronary arterial thrombi sometimes induce a no-reflow phenomenon after intervention whereby there is sufficient reperfusion. The greater susceptibility of the right coronary artery to development of large thrombi makes successful reperfusion more difficult, therefore the characteristics of the pathological images of coronary arterial thrombi according to the infarct-related coronary artery were investigated.

METHODS AND RESULTS

Coronary arterial thrombi were extracted from 77 patients with acute myocardial infarction (AMI) using a thrombectomy catheter. The 36 patients had a thrombus containing atherosclerotic cells. Platelets, fibrin, and neutrophils were seen in all cases. The mean ratios of structural components of thrombi were 51.0 +/- 29.5% (mean +/- SD) of the platelet component, 19.9 +/- 25.7% of the erythrocyte component and 11.9 +/- 22.5% of atherosclerosis component. Erythrocyte-rich thrombi and mixed thrombi mainly composed of erythrocytes were seen in 14 of the 30 cases involving the right coronary artery, 6 of the 35 cases in the left anterior descending artery, 2 of the 11 cases of the left circumflex artery, and in the 1 case of saphenous vein bypass graft. There was significantly more erythrocyte component in the thrombi from the right coronary artery (28.7 +/- 30.1%) than in those from the left coronary artery (12.1 +/- 18.4%).

CONCLUSION

Coronary artery thrombi in AMI are composed principally of platelets. Atherosclerotic cells were identified within thrombi from some patients. In the right coronary artery there were many more thrombi that were rich in erythrocytes than in thrombi from the left coronary artery.

Prediction of no-reflow phenomenon after successful percutaneous coronary intervention in patients with acute myocardial infarction: intravascular ultrasound findings

Plaque characterization by intravascular ultrasound (IVUS) before percutaneous coronary intervention (PCI) was evaluated in 81 consecutive patients with acute myocardial infarction (AMI) to establish if IVUS can predict the occurrence of the 'no-reflow' phenomenon. Angiographic no-reflow was defined as TIMI flow grade 1 or 2 without any mechanical obstruction in the epicardial artery. Patients were divided into 2 groups according to the post-PCI angiograms: normal flow (group R, n=60) and no-reflow (group NR, n=21). Although the incidence of either soft or noncalcified plaque was not statistically different between the groups, positive vessel remodeling was more frequent in group NR than in group R (57.1% vs 31.6%, p<0.05). Lipid core was also more frequently found in group NR than in group R (61.9% vs 25.0%, p<0.01). Positively remodeled vessels with lipid-rich plaques as characterized by IVUS before PCI predicted the occurrence of angiographic no reflow with a sensitivity of 43% and a specificity of 60%.