MRI discriminates thrombus composition and ST resolution after percutaneous coronary intervention in patients with ST-elevation myocardial infarction

Mean Activated Clotting Time of Patients Receiving Intravenous Heparin and Undergoing Primary Percutaneous Coronary Intervention for ST Elevation Myocardial Infarction

Introduction The most prevalent cause of death is acute myocardial infarction (AMI). Primary percutaneous coronary intervention (PPCI) has replaced thrombolysis as the recommended therapeutic option for individuals with ST-segment elevation myocardial infarction (STEMI). However, more effective anticoagulation regimes are required for PCI due to the limitations of unfractionated heparin. Objective This study aimed to ascertain the connection between the mean activated clotting time and the risk of bleeding and infarcts in individuals receiving intravenous heparin during PPCI for STEMI. Methods This was a one-year prospective observational study carried out at the National Institute of Cardiovascular Diseases (NICVD), Karachi, Pakistan. Results The majority (70.15%) were male, with a mean age of 56.08 ± 8.92 years. Following PPCI, the average active clotting time (ACT) was 350.56 ± 39.62 seconds (range 255 to 453), compared to the pre-PPCI mean of 504.15 ± 38.98 seconds. ACT was considerably higher in female patients, smokers, and overweight patients. The mean ACT was not significantly higher in patients with hypertension (HTN) and dyslipidemia (DLD). Conclusion The ACT range in this investigation was 255 to 453 seconds, and there was no discernible relationship between ACT readings and problems related to bleeding and ischemia. To determine who is more at risk, bleeding risk models should be used and improved further before catheterization.

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

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

Increased von Willebrand factor, P-selectin and fibrin content in occlusive thrombus resistant to lytic therapy

Therapeutic fibrinolysis is ineffective in 40 % of ST-segment elevation acute myocardial infarction (STEMI) patients, but understanding of the mechanisms is incomplete. It was our aim to compare the composition of coronary thrombus in lysis-resistant STEMI patients with that of lysis-sensitive patients. Intracoronary thrombi (n=64) were obtained by aspiration in consecutive STEMI patients. Of them, 20 had received fibrinolysis and underwent rescue percutaneous coronary intervention (r-PCI, lysis-resistant patients) and 44 underwent primary PCI (p-PCI). Lysis-sensitivity was determined in vitro by clot permeability measurements and turbidimetric lysis in plasma of 44 patients undergoing p-PCI and 20 healthy donors. Clot-lysis sensitivity was defined as a clot-lysis time not greater than 1 SD over the mean of healthy donors. Coronary thrombus composition in 20 lysis-resistant and in 20 lysis-sensitive patients was analysed by immunofluorescence with confocal microscopy. Plasma biomarkers (P-selectin, VWF, PAI-1, t-PA, D-dimer, TF pathway markers, plasmin and CD34+) were measured simultaneously on peripheral blood. Lysis-resistant clots had higher levels of fibrin (p=0.02), P-selectin (p=0.03) and VWF (p=0.01) than lysis-sensitive clots. Among thrombi obtained ≤ 6 hours after onset of symptoms, those from lysis-resistant patients showed a higher content in fibrin than those from p-PCI patients (p=0.01). Plasma PAI-1 (p=0.02) and D-dimer levels were significantly higher (p=0.003) in lysis-resistant patients, whereas plasmin levels were lower (p=0.03). Multivariate analysis showed the content of fibrin and VWF within thrombus as predictors of thrombolysis resistance. In conclusion, coronary thrombi in STEMI patients resistant to fibrinolysis are characterised by higher fibrin, P-selectin and VWF content than lysis-sensitive thrombi.

The role of diabetes mellitus in the composition of coronary thrombi in patients presenting with acute ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention

BACKGROUND

Although diabetes mellitus (DM) is a predictor of poor outcomes in patients with ST-segment elevation myocardial infarction (STEMI), few studies have analyzed the impact of DM on the constituency of coronary thrombi.

OBJECTIVES

Comparing morphologic and histopathologic aspects of coronary thrombi in STEMI patients with and without DM who underwent primary percutaneous coronary intervention.

METHODS

All consecutive patients with STEMI admitted to our institution between April 2010 and December 2012 (n = 1,548) were considered for inclusion. Thrombus material was obtained by aspiration thrombectomy; morphologic and histopathologic aspects were assessed by 3 independent pathologists blinded to clinical characteristics and outcomes. Patients with DM were compared with those without DM. A sensitivity analysis was performed using a propensity score.

RESULTS

During the study period, coronary thrombi material from 259 patients was obtained, of whom 19% (n = 49) had diabetes. Diabetic patients were older (P = .10), had a higher frequency of hypertension (P < .01) and dyslipidemia (P = .03), and had a trend to a longer time from the onset of chest pain to hospital arrival (P = .08). The number of retrieved fragments, the size of the thrombi and its composition (leukocytes, fibrin, and erythrocytes percent), and thrombus age and color were similar between patients with or without DM. There were also no statistically significant differences in thrombus constituency of the propensity score-matched patients (n = 92).

CONCLUSIONS

In this study, morphologic and histopathologic constituency of coronary thrombi in the setting of a ST-elevation myocardial infarction was not significantly different between patients with or without DM. This finding was intriguing and deserves further investigation.

Changes in thrombus composition and profilin-1 release in acute myocardial infarction

AIM

Thrombus formation is a dynamic process regulated by flow, blood cells, and plasma proteins. The present study was performed to investigate the characteristics of human coronary thrombus in ST-segment elevation myocardial infarction (STEMI).

METHODS AND RESULTS

Patients admitted with ST-elevation myocardial infarction, in which thrombectomy was performed, were included (n = 86). Intracoronary thrombi and blood from the culprit coronary site and the systemic circulation were obtained during percutaneous coronary intervention (PCI). Thrombi were categorized by onset-of-pain-to-PCI elapsed time in thrombus of <3 (T3) and more than 6 h of evolution (T6). Clinical, morphological, and proteomic variables were investigated. While T3 were mainly composed by platelets and fibrin(ogen), T6 were characterized by a reduced platelet content, increased leucocytes infiltration (including monocytes, neutrophils, T-cells, and B-cells), and appearance of undifferentiated progenitor cells. Significant differences between T3 and T6 were found in the cell cytoskeleton-associated proteome (beta-actin and tropomyosin 3 and 4). By discovery proteomics, we have identified profilin-1 (Pfn-1) in the coronary thrombi and detected higher levels in T3 than in T6. While plasma Pfn-1 levels were low in T3 patients, levels significantly increased in both coronary and peripheral circulation in T6 patients indicating release. In vitro platelet aggregation studies showed that platelets secrete Pfn-1 upon complete activation.

CONCLUSION

Coronary thrombi show rapid dynamic changes both in structure and cell composition as a function of elapsed onset-of-pain-to-PCI time. Aged ischaemic thrombi were more likely to have reduced Pfn-1 content releasing Pfn-1 to the circulation. Onset-of-pain-to-PCI elapsed time in STEMI patients and hence age of occlusive thrombus can be profiled by Pfn-1 levels found in the peripheral circulation.

Cardioembolic stroke: Protective effect of a severe internal carotid artery stenosis in a patient with cardiac embolism

Cardioembolic stroke is generally caused by intracranial artery occlusion. Clots may be identified in the intracranial vessels by means of conventional neuroimaging in the acute phase. High-resolution ultrasonography may show some features suggestive of cardiac emboli when occluding extracranial carotid arteries. We describe a patient with cardioembolic ischemic stroke in the right hemisphere in whom a left internal carotid artery stenosis paradoxically protected the ipsilateral hemisphere from distal intracranial embolism. The patient also presented multiple acute ischemic embolic lesions in the right middle cerebral artery territory and in the right occipital lobe, which was fed by the posterior cerebral artery, anomally originating from the right carotid siphon. Interestingly, the left internal carotid artery--which showed a severe preexisting stenosis--was occluded by the cardiac clot, whereas the right internal carotid artery only presented a moderate stenosis that had probably allowed the clots to pass. Therefore, the severe left internal carotid artery stenosis may have blocked the cardiac embolus, preventing it from reaching the ipsilateral hemisphere.

Red versus white thrombi in patients with ST-elevation myocardial infarction undergoing primary percutaneous coronary intervention: clinical and angiographic outcomes

BACKGROUND

Aspiration thrombectomy is used in primary percutaneous coronary interventions, but the importance of thrombus constituency has been scarcely investigated. The objective of this study was to evaluate thrombus constituency and its association with clinical, laboratory, and angiographic findings in patients with ST-segment elevation myocardial infarction.

METHODS

From April 2010 to May 2011, 562 patients with ST-segment elevation myocardial infarction undergoing primary percutaneous coronary interventions were considered for inclusion, and information on thrombi characteristics was available for 113 patients. Thrombus material were obtained and classified as white or red based on its constituency. Samples were analyzed by 3 independent pathologists blinded to clinical characteristics.

RESULTS

The mean age of patients was 58.6 ± 12.7 years, and 69% were men. White thrombi were present in 31% of cases, and red thrombi, in 69%. Patients with white thrombi had smaller vessels and lower ischemic times. All other clinical, angiographic, and laboratory characteristics did not differ. White thrombi were smaller and associated with fibrin infiltration, whereas red thrombi were associated with red blood cell infiltration. Thirty-day death rates were lower in patients with white thrombi than red (0% vs 10.1%, respectively; P = .05), as were 30-day major adverse cardiac event rates (4.2% vs 13.9%; P = .10). Total ischemic time was well correlated with fibrin infiltration (R = -0.30; P < .01), red blood cell infiltration (R = 0.27; P < .01), and thrombus volume (R = 0.22; P = .02).

CONCLUSIONS

White thrombi were present in one-third of cases and were associated with lower ischemic times, higher fibrin infiltration, smaller thrombus volume, and lower mortality. These findings suggest that thrombus constituency may be a useful prognostic tool in this setting.

[Update on ischemic heart disease]

This article contains a review of the main developments reported in 2011 on the pathophysiology, prevention, prognosis and treatment of chronic coronary artery disease and acute coronary syndrome, with or without ST-segment elevation. It also discusses the recommendations of the latest clinical practice guidelines.