Histopathologic correlates of unstable ischemic syndromes in patients undergoing directional coronary atherectomy: in vivo evidence of thrombosis, ulceration, and inflammation

Long-term outcomes of patients with acute coronary syndrome and nonobstructive coronary artery disease

Patients with acute coronary syndrome (ACS) and nonobstructive coronary artery disease (CAD) have a substantial risk of subsequent coronary events within 1 year. The aim of the present study was to evaluate the prevalence, long-term outcomes, and adherence to oral antiplatelet therapy in patients with ACS and nonobstructive CAD compared with patients with ACS and obstructive CAD who had undergone percutaneous coronary intervention. Nonobstructive CAD was defined as an angiographic finding of <50% diameter stenosis in any major epicardial artery. These patients were further stratified into 2 groups: those with normal coronary arteries (0% angiographic stenosis) and those with mild CAD (0% to 50% angiographic stenosis). Major adverse cardiac events, defined as death, myocardial infarction, ACS leading to hospitalization, and nonfatal stroke, were recorded and compared with a historical control group of patients with ACS and obstructive CAD who had undergone percutaneous coronary intervention. Of 2,438 consecutive patients with ACS undergoing coronary angiography, 318 (13%) had nonobstructive CAD. Of the 318 with nonobstructive CAD, 160 had normal coronary arteries and 158 had mild CAD. Patients with obstructive CAD had experienced greater rates of major adverse cardiac events at 26 ± 16 months (16.6% vs 9.1%, p = 0.001), driven by a greater rate of myocardial infarction compared with those without (5.3% vs 0%, p <0.001). However, the rate of death, ACS leading to hospitalization, and stroke was similar. After adjusting for baseline characteristics, no difference was found in the risk of major adverse cardiac events across the groups. Only 50% of patients with nonobstructive CAD were prescribed dual antiplatelet therapy. In conclusion, patients with ACS and nonobstructive CAD remain at high risk of long-term recurrent ischemic events.

MTHFR C677T polymorphism and its relationship to myocardial infarction in the Eastern Black Sea region of Turkey

BACKGROUND AND AIMS

An association of homozygous MTHFR 677T genotypes with elevated plasma homocysteine level has been documented, but results are still controversial. We aimed to investigate prevalence of the C677T polymorphism in patients with acute myocardial infarction (MI) in the Eastern Black Sea region of Turkey.

METHODS

We studied genomic DNA of 231 unrelated patients (aged 59 ± 13 years; 175 male, 56 female) with first anterior acute MI and 242 healthy controls (aged 54 ± 19 years; 182 male, 60 female) using real-time polymerase chain reaction kits for the MTHFR C677T mutation.

RESULTS

Prevalence of MTHFR C677T mutant genotype was 49.1% (CT: 45.8%, TT: 3.3%) in controls and 48.45% (CT: 38.5%, TT: 9.95%) in patients with acute MI. The TT mutation was more frequent in patients with acute MI than in controls (9.95 vs. 3.3%) (OR; 3.23, 95% CI; [1.34-8.05], p = 0.003).

CONCLUSIONS

The MTHFR gene homozygote TT mutation is a risk factor for patients with MI in the eastern Black Sea Turkish Population.

Effects of drug-eluting stents on systemic inflammatory response in patients with unstable angina pectoris undergoing percutaneous coronary intervention

Inflammatory markers are elevated in acute coronary syndromes, and are also known to play a crucial role in the pathogenesis of neointimal proliferation and stent restenosis. Drug-eluting stents (DESs) have been shown to decrease stent restenosis in different studies. In this study, we aimed to investigate the effect of treatment with DESs on systemic inflammatory response in patients with unstable angina pectoris who underwent percutaneous coronary intervention (PCI). We compared plasma high-sensitivity C-reactive protein (hsCRP), human tumor necrosis factor alpha (Hu TNF-alpha), and interleukin 6 (IL-6) levels after DES (dexamethasone-eluting stent [DEXES], and sirolimuseluting stent [SES]) implantation with levels after bare metal stent (BMS) implantation. We performed PCI with a single stent in 90 patients (62 men; 59 +/- 9 years of age; n = 30 in the BMS group, n = 30 in the DEXES group, n = 30 in the SES group) who had acute coronary syndrome. Plasma hsCRP, Hu TNF-alpha, and IL-6 levels were determined before intervention and at 24 h, 48 h, and 1 week after PCI. The results were as follows. Plasma hsCRP levels at 48 h (11.19 +/- 4.54, 6.43 +/- 1.63 vs 6.23 +/- 2.69 mg/l, P = 0.001) after stent implantation were significantly higher in the BMS group than in the DES group; this effect persisted for 7 days (P = 0.001). Plasma Hu TNF-alpha levels at each time point were higher in the SES group than in the BMS and DEXES groups (P < 0.05). The time course of Hu TNF-alpha values was similar in all groups. Although IL-6 levels at baseline and at 24 and 48 h showed no statistically significant difference between the study groups, postprocedural values at 7 days were slightly statistically significant in the SES group (P = 0.045). Drug-eluting stents showed significantly lower plasma hsCRP levels after PCI compared with BMSs. This may reflect the potent effects of DESs on acute inflammatory reactions induced by PCI.

Effect of dexamethasone-eluting stents on systemic inflammatory response in patients with unstable angina pectoris or recent myocardial infarction undergoing percutaneous coronary intervention

The effect of treatment with steroid-eluting stents on systemic inflammatory response was investigated in patients with unstable angina pectoris or recent myocardial infarction who underwent percutaneous intervention. Compared with controls, dexamethasone-eluting stents significantly reduced C-reactive protein peak levels 48 hours after the procedure; this effect persisted for 7 days and was particularly evident in patients with elevated (>/=3 mg/L) preprocedural C-reactive protein values. Patients receiving a dexamethasone-eluting stent had lower adverse events during follow-up.

Intravascular ultrasound evaluation of ruptured plaque in the left main coronary artery misinterpreted as an aneurysm by angiography

We report a patient who demonstrated a left main coronary aneurysm by angiography. Intravascular ultrasound (IVUS) revealed that it was in fact an ulceration, which indicated ruptured plaque. This case provides evidence that IVUS can permit a more powerful definition of ruptured plaque than angiography. On IVUS, ulceration exhibits significantly different characteristics from aneurysm.

Detection of increased temperature of the culprit lesion after recent myocardial infarction: the favorable effect of statins

BACKGROUND

Increased thermal heterogeneity has been demonstrated in atherosclerotic plaques, with the higher temperature recorded in acute myocardial infarction (MI). Dietary or treatment interventions reduce heat production. The purpose of the present study was to investigate whether increased plaque temperature is maintained for a prolonged period after MI and the role of statin administration.

METHODS

We enrolled 55 patients, 29 with recent MI and 26 with chronic stable angina (CSA). Total cholesterol, C-reactive protein (CRP), interleukin-6 (IL-6) and soluble adhesion molecules were measured in the study population. All patients underwent coronary plaque temperature measurements. Temperature difference (DeltaT) was designated as the temperature of the culprit atherosclerotic plaque minus the temperature of the proximal healthy vessel wall.

RESULTS

Under treatment with statins were 19 patients with recent MI and 14 with CSA. In patients with recent MI DeltaT was 0.19 +/- 0.18 degrees C, while in patients with CSA was 0.10 +/- 0.08 degrees C (P = .03). Patients treated with statins had lower DeltaT compared to untreated patients (0.10 +/- 0.11 versus 0.20 +/- 0.18 degrees C, P = .01). Treated patients with recent MI had similar DeltaT compared to CSA patients treated with statins (0.13 +/- 0.13 versus 0.07 +/- .06 degrees C, P = .14), while untreated patients with recent MI had substantially increased DeltaT compared to untreated patients with CSA (0.28 +/- 0.22 versus 0.14 +/- 0.10 degrees C, P = .04). DeltaT was positively correlated with CRP (R = 0.50, P < .01), IL-6 (R = 0.58, P < .01), and intercellular adhesion molecule-1 (R = 0.40, P = .03) levels.

CONCLUSION

Increased plaque temperature is observed for an extended period after myocardial infarction, indicating that the inflammatory process is sustained after plaque rupture. Statins have a beneficial effect after MI on plaque temperature.

Multiple coronary aneurysms resulting from isolated coronary vasculitis in an elderly patient

An 81-year-old man developed multiple coronary aneurysms, including the left main truncus, that were unexpectedly found by coronary angiography. He had been followed-up for 14 years because of angina pectoris; his initial coronary angiograms in 1985 showed some stenotic segments but no aneurysmal changes. The patient died of gastric cancer in March 2000. On microscopic examination of the coronary arteries, the prominent feature was an inflammatory reaction in the medial layer, comprising chiefly small lymphocytes and plasma cells. The internal and the external elastic membranes were destroyed, presumably causing the aneurysmal dilatation of the vessels. There was a moderate degree of concomitant atherosclerotic fibrointimal thickening. No evidence of vasculitis was seen in sections of the aorta, peripheral arteries, and other major organs. The present case is unique because the cellular infiltrates were confined to the coronary media and although a definite diagnosis was not made, it was probably an atypical form of vasculitic disease; namely, isolated coronary vasculitis.

Widespread coronary inflammation in unstable angina

BACKGROUND

Inflammation within vulnerable coronary plaques may cause unstable angina by promoting rupture and erosion. In unstable angina, activated leukocytes may be found in peripheral and coronary-sinus blood, but it is unclear whether they are selectively activated in the vascular bed of the culprit stenosis.

METHODS

We measured the content neutrophil myeloperoxidase content in the cardiac and femoral circulations in five groups of patients: two groups with unstable angina and stenosis in either the left anterior descending coronary artery (24 patients) or the right coronary artery (9 patients); 13 with chronic stable angina; 13 with variant angina and recurrent ischemia; and 6 controls. Blood samples were taken from the aorta, the femoral vein, and the great cardiac vein, which selectively drains blood from the left but not the right coronary artery.

RESULTS

The neutrophil myeloperoxidase content of aortic blood was similar in both groups of patients with unstable angina (-3.9 and -5.5, with negative values representing depletion of the enzyme due to neutrophil activation) and significantly lower than in the other three groups (P<0.05). Independently of the site of the stenosis, the neutrophil myeloperoxidase content in blood from the great cardiac vein was significantly decreased in both groups of patients with unstable angina (-6.4 in those with a left coronary lesion and -6.6 in those with a right coronary lesion), but not in patients with stable angina and multiple stenoses, patients with variant angina and recurrent ischemia, or controls. There was also a significant transcoronary reduction in myeloperoxidase content in both groups with unstable angina.

CONCLUSIONS

The widespread activation of neutrophils across the coronary vascular bed in patients with unstable angina, regardless of the location of the culprit stenosis, challenges the concept of a single vulnerable plaque in unstable coronary syndromes.

Histopathologic evaluation of coronary artery thrombi obtained by directional coronary atherectomy in patients with restenosis-induced unstable angina pectoris

The pathogenesis of unstable angina pectoris (UAP) following percutaneous transluminal coronary angioplasty (PTCA) or directional coronary atherectomy (DCA) has not been adequately investigated, so the present study aimed to determine whether thrombi are present in restenotic lesions. The study group comprised 14 patients (16 arterial branches) with angina pectoris in whom either PTCA or DCA was performed and who had developed UAP associated with restenosis, and who then underwent DCA of the restenosed lesion (R-UAP group). The control groups comprised individuals with UAP undergoing DCA with no prior history of PTCA or DCA (P-UAP group; n=29, 29 branches), patients with acute myocardial infarction (AMI group; n=34, 34 branches), and patients with stable angina pectoris (SAP group; n=31, 33 branches). The presence of thrombi was determined by light microscopy of histologic specimens. Thrombus was present in only 1 of the 16 (6.3%) branches in the R-UAP group. 21 of the 29 (72.4%) branches in the P-UAP group, and in 25 of the 34 (73.5%) in the AMI group. In the SAP group, it was detected in only 2 of the 33 (7.1%) branches. The incidence of thrombus was significantly lower in the R-UAP group than in the P-UAP group. In conclusion, the role of thrombus is limited in causing post-interventional UAP at restenosed sites.

Plasma Markers of Procoagulant Activity Among Individuals with Coronary Artery Disease

Background: There is compelling evidence that coronary atherosclerosis represents a chronic active process characterized by inflammation, impaired fibrinolysis, intermittent plaque rupture, and luminal thrombosis. Identifying readily measurable plasma markers of procoagulant activity may have an important role in both tracking and understanding the natural history, as well as in defining the ideal treatment, of patients with coronary artery disease. Methods/Results: A total of 30 men and women with suspected coronary artery disease who underwent outpatient cardiac catheterization were sampled for evidence of thrombin generation and fibrin formation in plasma. Compared with healthy controls, patients had significantly increased concentrations of fibrinopeptide A (18.8 +/- 10.8 ng/ml vs. 2.5 +/- 2.3, p < 0.001), thrombin-antithrombin complexes (8.13 +/- 4.56 ng/ml vs. 3.4 +/- 3.0, p < 0.001), and prothrombin activation fragment 1.2 (0.15 +/- 0.09 ng/ml vs. 0.12 +/- 0.19, p = 0.01). There was a statistically insignificant trend toward increased thrombin-antithrombin complex concentrations in patients with hypercholesterolemia (p = 0.10). Patients with angiographically defined coronary artery disease involving two or more vessels were found to have heightened thrombin generation and fibrin formation compared with those with single vessel disease. Conclusions: Patients with atherosclerotic coronary artery disease exhibit evidence of heightened procoagulant activity, including thrombin generation and fibrin formation. This observation, coupled with those derived from other recent studies, support the hypothesis that coronary atherosclerosis represents a chronic active process typified by vessel wall inflammation and recurrent thrombosis. Future efforts in disease prevention and treatment must consider these fundamental pathobiologic properties.

Detecting and differentiating white from red coronary thrombus by angiography in angina pectoris and in acute myocardial infarction

To determine the ability to detect thrombus by angiography, angioscopy was performed before angiography in patients undergoing interventional procedures and the data collected in a blinded fashion. These data demonstrated that the sensitivity of angiography to detect white thrombus was 50% and the specificity was 95%, whereas the sensitivity and specificity to detect red thrombus was 100%, respectively; the positive and negative predictive value of detecting thrombus in general was 89% and 83%, respectively.

Carotid rupture and intraplaque hemorrhage: immunophenotype and role of cells involved

BACKGROUND

A complete immunohistochemical characterization in complicated carotid plaques is still lacking. The cellular components of 165 carotid endarterectomy specimens were analyzed to assess their role in the pathogenesis of plaque rupture and intraplaque hemorrhage without rupture.

METHODS AND RESULTS

The fibrous caps at the sites of plaque rupture showed CD68+ macrophages, T-lymphocytes, and scarce B-lymphocytes. Ruptured plaques showed mononuclear infiltrates in the caps, shoulders, and bases of the plaques in 85% of the cases. Only 46% of nonruptured plaques showed such infiltrates (P <.0001). Two types of lipid cores were recognized: avascular or mildly vascularized and highly vascularized. The vessels of the latter type reacted with CD31 and CD34. In 57.5% of the cases, the base and the shoulders of the plaques showed neoformed, CD34+ vessels, often surrounded by mononuclear infiltrates. Intraplaque hemorrhage without rupture had highly vascularized lipid cores in all cases. T-lymphocytes and macrophages were in close contact with neoformed vessels.

CONCLUSIONS

Plaque rupture is characterized by mononuclear cell infiltration of the caps, whereas intraplaque hemorrhage without rupture is characterized by extensive vascularization of the plaque.

Increased endothelial expression of intercellular adhesion molecule-1 in symptomatic versus asymptomatic human carotid atherosclerotic plaque

BACKGROUND AND PURPOSE

The mechanisms that cause carotid atherosclerotic plaque to become symptomatic remain unclear. Evidence suggests that mediators of inflammation are not only instrumental in the formation of plaque but may also be involved in the rapid progression of atheromatous lesions leading to plaque fissuring, endothelial injury, and intraluminal thrombosis. Our goal is to determine whether intercellular adhesion molecule-1 (ICAM-1), a known component of the inflammatory pathway, is preferentially expressed on symptomatic versus asymptomatic carotid plaques.

METHODS

Carotid plaques from symptomatic (n = 25) and asymptomatic (n = 17) patients undergoing carotid endarterectomy with lesions involving >60% stenosis were snap-frozen at the time of surgery. Immunofluorescence studies were performed to measure the percentage of luminal endothelial surface that expressed ICAM-1. The relationships of stroke risk factors, white blood cell count, percent stenosis, and soluble ICAM-1 (sICAM-1) plasma levels to endothelial ICAM-1 expression were investigated.

RESULTS

An increased expression of ICAM-1 was found in the high-grade regions of symptomatic (29.5%+/-2.4%, mean+/-SEM) versus asymptomatic (15.7%+/-2.7%, mean+/-SEM) plaques (P=0.002) and in the high-grade versus the low-grade region of symptomatic plaques (29.5+/-2.4, mean+/-SEM, versus 8.9+/-1.6; P<0.001). Plasma sICAM-1 levels were not predictive of symptomatic disease, and no significant correlation between risk factor exposure and endothelial ICAM-1 expression was found.

CONCLUSIONS

An elevation in ICAM-1 expression in symptomatic versus asymptomatic plaque suggests that mediators of inflammation are involved in the conversion of carotid plaque to a symptomatic state. The data also suggest a differential expression of ICAM-1, with a greater expression found in the high-grade region than in the low-grade region of the plaque specimen.

Association of coronary plaque rupture and atherosclerotic inflammation

Coronary plaque inflammation may promote plaque rupture and thrombosis. To test this hypothesis, 351 coronary plaques from 83 patients were formalin-fixed and stained with haematoxylin and eosin. There were six groups: (1) ruptured plaques; (2) intact plaques from recently infarcted hearts; (3) plaques from hearts with severe coronary atherosclerosis without identifiable thrombosis; (4) native explanted hearts with severe coronary atherosclerosis; (5) cardiac transplant atherosclerosis; and (6) fatalities unrelated to coronary atherosclerosis. Selected arteries were immunostained for leukocyte markers and serially sectioned to identify plaque rupture. There were infiltrates of CD68-positive macrophages and CD3- and CD8-positive T cells adjacent to all plaque ruptures. Labelling with HLA-DR and CD30 indicated inflammatory cell activation. Plaque rupture was strongly statistically associated with the severity and frequency of superficial plaque inflammation but not that of deep plaque inflammation. Although atherosclerotic inflammation has been identified adjacent to rupture, this is its first comparison with control plaques. These results support the concept that inflammation in the fibrous cap is particularly associated with plaque rupture.

Expression of neutrophil and monocyte CD11B/CD18 adhesion molecules at different sites of the coronary tree in unstable angina pectoris

To assess the site of leukocyte activation in unstable angina, the expression of neutrophil and monocyte CD11B/CD18 adhesion molecules in 26 patients was measured from blood samples taken from the coronary ostium, the coronary sinus, and the coronary artery just distal to the culprit lesion (postobstructive chamber). CD11B/CD18 adhesion molecules detected by direct immunofluorescence evaluated by flow cytometry were significantly higher in the coronary sinus blood than in both the coronary ostium and the postobstructive chamber blood, suggesting that leukocyte activation takes place at the microcirculatory interface with the injured myocardium, probably as the result of short but repeated episodes of myocardial ischemia.

Temporal relation between ischemic episodes and activation of the coagulation system in unstable angina

BACKGROUND

Although a major role of coronary thrombosis in the pathogenesis of unstable angina has been demonstrated, the results of a series of studies have suggested that activation of the hemostatic system may not be confined to ischemic episodes. The purpose of this study was to investigate the temporal relation between ischemic episodes and activation of the coagulation system in unstable angina.

METHODS AND RESULTS

Thrombin-antithrombin III (TAT) and prothrombin fragment 1 + 2 (F1 + 2) levels were measured in 13 patients during spontaneous ischemic episodes (time 0, 5, and 15 minutes and 1 hour) to evaluate the time course of the activation of the coagulation system associated with the development of ischemia (protocol A). TAT and F1 + 2 levels were also measured in 28 patients with unstable angina on admission to hospital (every 6 hours for 24 hours and daily for 3 days) to assess their temporal relation with ischemic episodes (protocol B). In protocol A, TAT and F1 + 2 levels were elevated in 10 of 13 patients (77%) in at least 1 sample. The median value of TAT showed a peak at 5 minutes and returned to baseline within 15 minutes (P < .05), consistent with its plasma half-life of 5 minutes, whereas the median value of F1 + 2 showed no significant changes, possibly because of its longer half-life, which tends to dampen sudden bursts of thrombin production. In protocol B, activation of the clotting system was found in 10 of 33 samples (30%) temporally related to ischemia and also in 23 of 150 (15%, P = .07) of those not temporally related to ischemia.

CONCLUSIONS

Our study demonstrates that patients with active unstable angina develop frequent bursts of thrombin production not necessarily associated with ischemic episodes and that, conversely, some ischemic episodes are not associated with evidence of thrombin activation.

Pathophysiology and inflammatory aspects of plaque rupture

Atherosclerotic plaque disruption with superimposed thrombosis is the main cause of acute coronary events. At present it is not known specifically how various risk factors influence the development and configuration of coronary plaques. The risk of plaque disruption depends more on plaque composition and vulnerability (plaque type) than on the degree of stenosis (plaque size). Lipid accumulation and chronic inflammation, particularly macrophage activities, seem to influence the development and the stability of a plaque and thus its propensity to rupture. Macrophages have the ability to secrete proteolytic enzymes and often infiltrate the region of imminent plaque rupture, and disruption may be associated with a generalized inflammatory reaction. Further, plaque disruption tends to occur at points where the plaque surface is weakest, corresponding to locations where mechanical and hemodynamic forces have their highest impact. The risk of plaque disruption is a function of both plaque vulnerability (intrinsic disease) and rupture triggers (extrinsic forces). The former predisposes the plaque to rupture; the latter may precipitate rupture. The danger of vulnerable plaques, however, is not related to disruption as such but to the resulting thrombosis. The magnitude of this thrombotic response and the ensuing flow obstruction depends on the contents and quantity of exposed thrombogenic plaque material, the degree of pre-existing stenosis, and the systemic thrombotic tendency. The thrombotic response is a dynamic process that is decisive for the clinical presentation and the outcome.

Differential expression of tissue factor protein in directional atherectomy specimens from patients with stable and unstable coronary syndromes

BACKGROUND

Tissue factor (TF) is a cell membrane-associated protein that catalyzes the rate-limiting step of the extrinsic coagulation pathway, which is the major source of thrombin production in vivo. To explore the potential role that TF may play in ischemic coronary syndromes, directional coronary atherectomy specimens were tested for the presence of TF protein using immunohistochemical techniques.

METHODS AND RESULTS

Frozen sections from atherectomy specimens in 61 patients were examined for TF expression using an IgG murine monoclonal antibody against human TF. Patients were classified according to their admission diagnosis as having either an unstable or a stable coronary syndrome. An unstable coronary syndrome was defined as either angina pectoris occurring at rest or post-myocardial infarction (< 1 week) angina. Stable coronary syndromes included patients with stable, progressive, and new-onset (< 6 weeks) angina without rest pain. TF was detected in 15 (43%) of 35 patients with unstable coronary syndromes versus only 3 (12%) of 26 patients with stable coronary syndromes (odds ratio, 5.7; 95% confidence interval, 1.3 to 24.3; P = .018). Within the subgroup of patients with unstable coronary syndromes, TF was detected in 14 (60%) of 25 patients with de novo lesions versus only 1 (10%) of 10 patients with a restenosis lesion (P < .02). An additional 8 patients with stable coronary syndromes due to a restenosis lesion were also negative for TF. Therefore, the overall incidence of TF expression was only 6% (1 of 18) in restenosis lesions compared with 33% (14 of 43) in de novo lesions (P < .03).

CONCLUSIONS

This study provides the first description of TF protein expression in human coronary artery lesions in vivo. Tissue factor was readily detected in de novo lesions in patients with unstable coronary syndromes, suggesting a role for TF in the pathogenesis of this disease process. Conversely, TF was rarely detected in patients with restenosis lesions even if the resulting clinical presentation was an unstable coronary syndrome. These results may have implications for the management of patients with unstable angina from de novo lesions and patients with ischemic symptoms from a restenosis lesion.