Total cholesterol content of erythrocyte membranes is increased in patients with acute coronary syndrome: a new marker of clinical instability?

OBJECTIVES: We hypothesized that cholesterol content is increased in the circulating erythrocytes of patients with acute coronary syndrome (ACS) and may be a marker of clinical instability. We therefore sought to investigate whether cholesterol content differs in erythrocyte membranes of patients presenting with ACS compared to patients with chronic stable angina (CSA). BACKGROUND: Plaque rupture in ACS depends at least partly on the volume of the necrotic lipid core. Histopathologic studies have suggested that cholesterol transported by erythrocytes and deposited into the necrotic core of atheromatous plaques contributes to lipid core growth. METHODS: Consecutive angina patients were prospectively assessed; 120 had CSA (83 men, age 64 +/- 11 years) and 92 ACS (67 men, 66 +/- 11 years). Total cholesterol content in erythrocyte membranes (CEM) was measured using an enzymatic assay, and protein content was assessed by the Bradford method. RESULTS: The CEM (median and interquartile range) was higher (p < 0.001) in ACS patients (184 microg/mg; range 130.4 to 260.4 microg/mg) compared with CSA patients (81.1 microg/mg; range 53.9 to 109.1 microg/mg) (analysis of covariance). Total plasma cholesterol concentrations did not correlate with CEM levels (r = -0.046, p = 0.628). CONCLUSIONS: This study shows, for the first time, that CEM is significantly higher in patients with ACS compared with CSA patients. These findings suggest a potential role of CEM as a marker of atheromatous plaque growth and vulnerability. Large ad hoc studies are required to establish the clinical importance and pathogenic significance of CEM measurement.

Interleukin-18/interleukin-10 ratio is an independent predictor of recurrent coronary events during a 1-year follow-up in patients with acute coronary syndrome.

BACKGROUND: The pro-inflammatory cytokine IL-18 has been suggested to play a role in atherogenesis and atheromatous plaque rupture leading to the acute coronary syndrome (ACS). Conversely, the anti-inflammatory cytokine IL-10 seems to have an atheroprotective role. Patients with unstable coronary artery disease show an imbalance between serum levels of pro- and anti-inflammatory cytokines, and studies have shown that IL-18/IL-10 ratio is an independent predictor of adverse in-hospital events in patients with ACS. We assessed the long-term prognostic significance of admission interleukin-18 (IL-18)/interleukin-10 (IL-10) ratio for recurrent coronary events during a 1-year follow-up in patients presenting with an ACS. METHODS: We assessed independent predictors of the combined end-point using multiple logistic regression analysis, in 186 patients (138 men, 65+/-12 years) with ACS (75 STEMI, 65 NSTEMI and 46 unstable angina). The composite of cardiac death and re-hospitalization with non-fatal myocardial infarction, or unstable angina, was the pre-specified study end-point. Serum IL-10 and IL-18 levels were measured at study entry using commercially available ELISAs. RESULTS: During the 1-year follow-up, 48 (26%) patients had recurrent cardiac events and 138 (74%) were event-free. IL-18/IL-10 ratio predicted the occurrence of adverse cardiac events (OR 1.91, 95% CI 1.37-2.65, p<0.001), and was found to be an independent predictor among other established biochemical and clinical risk markers (OR 2.31, 95% CI 1.55-3.42, p<0.001). CONCLUSIONS: Serum IL-18/IL-10 ratio is an independent predictor of recurrent coronary events during long-term follow-up in patients presenting with ACS. Our study further supports the hypothesis that the balance between pro-inflammatory and anti-inflammatory cytokines may be an important determinant of patient outcome, suggesting a pathogenic role in plaque progression and instability.

Inflammatory and anti-inflammatory variable clusters and risk prediction in acute coronary syndrome patients: a factor analysis approach.

BACKGROUND: Numerous inflammatory mediators such as C-reactive protein (CRP), fibrinogen, interleukin-18 (IL-18), and inter-cellular adhesion molecule-1 (ICAM-1) have been proposed for risk stratification in acute coronary syndrome (ACS) patients. However, interactions between these markers have made it difficult to assess their true role in risk prediction. Factor analysis is a multivariable statistical technique that reduces a large number of intercorrelated variables to a smaller set of independent clusters, underlining physiological relationships. The aim of this study was to investigate, using factor analysis, a clustering of pro-inflammatory markers, anti-inflammatory cytokines such as interleukin-10 (IL-10) and HDL cholesterol, and to determine their role in prediction of risk of recurrent coronary events in ACS patients. METHODS: We assessed 320 consecutive patients (236 men; 67 years; IQ 58-74 years) admitted with ACS. The composite of cardiac death and re-hospitalization with non-fatal myocardial infarction, or unstable angina, was the pre-specified study end-point. Serum CRP, fibrinogen, HDL cholesterol, IL-10, IL-18 and ICAM-1 levels were measured at study entry. We assessed independent predictors of the combined end-point during a 1-year follow-up using multiple logistic regression analysis. RESULTS: Factor analysis identified three clusters which were arbitrarily interpreted as (1) a "systemic inflammation" cluster with positive loadings of CRP and fibrinogen, (2) a "local inflammation-endothelial dysfunction" cluster with positive loadings of IL-18 and ICAM-1 and (3) an "anti-inflammation" cluster comprising IL-10 and HDL cholesterol. Only the "anti-inflammation" cluster was a significant predictor (OR 0.66, 95% CI: 0.49-0.89) of adverse cardiac events during a 1-year follow-up and remained significant (OR 0.65, 95% CI: 0.48-0.88) in a multivariate model that included all three factors. CONCLUSIONS: Although inflammatory markers such as CRP predict future cardiovascular events in ACS patients, when all inflammatory mediators are taken into account in a prospective analysis of risk, markers reflecting anti-inflammatory mechanisms are better prognostic markers.

Apolipoprotein E genotype and circulating interleukin-10 levels in patients with stable and unstable coronary artery disease.

OBJECTIVES: This study was designed to assess the relation between apolipoprotein E (apoE) genotype and serum interleukin (IL)-10 levels in patients with acute coronary syndrome (ACS) and chronic stable angina (CSA). BACKGROUND: Genetic variations in the apoE gene affect the risk for coronary artery disease (i.e., carriers of the e4 allele have an increased risk). Increased levels of C-reactive protein (CRP), an inflammatory marker, correlate with an increased risk of acute coronary events, whereas increased IL-10 concentrations have an atheroprotective role. Studies have reported a negative association between the apoE e4 allele and CRP levels. METHODS: Apolipoprotein E genotypes were assessed in 166 consecutive ACS patients (119 men, mean age 68 years, interquartile range [IQR] 60 to 74 years) and 70 CSA patients (54 men, mean age 65 years, IQR 62 to 68 years). Serum IL-10 and CRP were assessed at study entry. RESULTS: Analysis of covariance showed that genetic variation in the apoE gene locus significantly influences serum IL-10 levels in both ACS (p = 0.009) and CSA patients (p = 0.013). Among ACS patients, IL-10 levels were lower in E3/E4 carriers compared with E3/E3 carriers (p = 0.01) and marginally lower compared with E2/E3 carriers (p = 0.065). Among CSA patients, IL-10 levels were lower in E3/E4 carriers compared with E2/E3 carriers (p = 0.004) and marginally lower compared with E3/E3 carriers (p = 0.086). CONCLUSIONS: The IL-10 concentrations differ in ACS and in CSA patients with different apoE genotypes. The e4 allele was associated with a trend toward lower IL-10 serum levels. Our results may provide an explanation of findings in previous studies that cardiovascular risk is higher in e4 carriers despite the presence of low CRP levels.

Alteplase treatment affects circulating matrix metalloproteinase concentrations in patients with ST segment elevation acute myocardial infarction.

INTRODUCTION: Matrix metalloproteinases (MMPs) are expressed in atherosclerotic plaques. Acute coronary syndromes may be precipitated by MMPs through degradation of the fibrous cap and subsequent plaque disruption. Serine proteases such as plasmin activate MMPs and may contribute to plaque events. Thrombolysis with recombinant tissue plasminogen activator (rtPA) is widely used for treatment of acute ST segment elevation myocardial infarction (STEMI). In the present study we assessed whether thrombolytic therapy with rtPA in patients with STEMI influences serum levels of MMP-2 and MMP-9. METHODS: We recruited 108 patients (92 men, mean age 64 +/- 12 years) with STEMI, of whom 84 (78%) received thrombolytic treatment with rtPA and 24 (22%) did not. MMP-2 and MMP-9 levels were assessed at hospital admission (baseline), and at 24 and 72 h after admission, using a commercially available ELISA. RESULTS: Overall, MMP-9 levels were higher in the thrombolysis group compared to patients without thrombolysis (p < 0.001). Thrombolysis treatment significantly affected the change in MMP-9 levels during the 72-h study period (p < 0.001). CONCLUSIONS: The present study showed that thrombolysis could affect circulating levels of MMP-9 in STEMI patients. Whether this effect may lead to plaque instability deserves further investigation.

The potential of D-dimer levels as a useful clinical marker of clotting state after the return of sinus rhythm.

Fibrin D-dimers levels have been advocated as a useful clinical marker of thrombogenesis. It is accepted that patients with atrial fibrillation (AF) are characterized by increased levels of plasmatic d-dimers. AF is a high risk factor for hypercoagulability, with a substantial risk of thromboembolism. The most effective way of minimizing the increased thromboembolic risk and treating patients' symptoms is to return the heart rhythm to sinus rhythm by electrical or chemical cardioversion. However, cardioversion of AF itself leads to a further increased risk of thromboembolism. A marker of coagulation activation would be useful to identify patients at the highest thromboembolic risk after cardioversion in AF patients. Indicators of hypercoagulability, such as d-dimers, appear to be a useful parameter for assessing the degree of hypercoagulability of AF patients after cardioversion. Mean changes in plasma d-dimers levels could be used as a useful clinical marker of the clotting state after the return of atrial systole.

Comparison of levels of matrix metalloproteinase-2 and -3 in patients with ischemic cardiomyopathy versus nonischemic cardiomyopathy.

It has been reported that circulating matrix metalloproteinase (MMP) levels are upregulated in patients with chronic heart failure. However, experimental studies indicate that differences in the profiles of MMPs and tissue inhibitors of metalloproteinase (TIMPs) may exist in ischemic compared with nonischemic cardiomyopathy. This study examined whether circulating levels of MMPs and TIMP-1 are related to the pathogenesis of heart failure. Circulating levels of MMP-2, MMP-3, and TIMP-1 were assessed in 52 patients with compensated end-stage chronic heart failure, including 26 patients (mean 64 +/- 7 years; 10 men) with ischemic cardiomyopathy (IC) and 26 (mean age 66 +/- 6 years; 14 men) with idiopathic dilated cardiomyopathy (IDC). Serum MMP-2 (p <0.001) and MMP-3 (p <0.001) levels were higher in patients with IDC than in those with IC. Serum TIMP-1 levels were lower in patients with IDC (p = 0.011) than in those with IC. This study shows that in patients with compensated end-stage chronic heart failure, circulating levels of MMP-2, MMP-3, and TIMP-1 are associated with the pathogenesis of heart failure.

Interleukin-18: interleukin-10 ratio and in-hospital adverse events in patients with acute coronary syndrome.

INTRODUCTION: Inflammatory mechanisms contribute to the development of acute coronary syndromes (ACS), and it has been suggested that an imbalance between pro- and anti-inflammatory responses may be an important determinant of recurrent cardiac events in this setting. Both increased serum levels of interleukin (IL)-18 and reduced concentrations of IL-10 have been shown to have prognostic significance in ACS. We sought to assess whether the ratio of serum IL-18/IL-10 levels has higher positive predictive value than the individual measurement of IL-10 and IL-18 in patients admitted to hospital with ACS. METHODS: We recruited 107 consecutive patients (79 men, mean age 65+/-12 years) with ACS (41 STEMI, 39 NSTEMI and 27 UA). The composite of cardiac death, recurrence of unstable angina, re-infarction, life threatening arrhythmias, and urgent revascularization during hospitalization was the pre-specified study end-point. We assessed independent predictors of the combined end-point using multiple logistic regression analysis. Serum IL-10 and IL-18 levels were measured at study entry using commercially available ELISAs. RESULTS: During hospitalization 44 patients (41%) had events and 63 (59%) had no events. Significantly higher odd ratios were found for IL-18/IL-10 ratio (1.74 95% CI 1.09-2.78) compared to individual IL-18 (1.46 95% CI 0.93-2.27) and 1/IL-10 (1.63 95% CI 1.04-2.56) measurements. CONCLUSION: Serum IL-18/IL-10 ratio is an independent predictor of in-hospital adverse events in patients with ACS. Our study strongly endorses the notion that an imbalance between pro and anti-inflammatory forces predisposes to plaque disruption and recurrent cardiovascular events.

N-terminal pro-B-type natriuretic peptide and matrix metalloproteinases in early and late left ventricular remodeling after acute myocardial infarction.

N-terminal pro-B-type natriuretic peptide (NT-pro-BNP) is a predictor of left ventricular remodeling. Matrix metalloproteinases (MMPs) contribute to collagen breakdown that is associated with ventricular remodeling after acute myocardial infarction (AMI). We assessed the association between circulating levels of NT-pro-BNP, MMP-2, and MMP-9 and their inhibitor (tissue inhibitor of metalloproteinase-1) early (24 and 72 hours) and late (7 and 30 days) after AMI in 108 patients who had ST-elevation AMI (90 men; mean age 60 years). Serum MMP-2 levels measured 24 and 72 hours after AMI were inversely associated with NT-pro-BNP levels, whereas MMP-9 serum levels were positively related. During late-stage remodeling after AMI, circulating concentrations of tissue inhibitor of metalloproteinase-1 were independently associated with NT-pro-BNP levels 7 and 30 days after AMI. This study shows that, in patients who have ST-elevation AMI, circulating levels of NT-pro-BNP are associated with MMPs in a species-specific and time-dependent manner.

Clotting state after cardioversion of atrial fibrillation: a haemostasis index could detect the relationship with the arrhythmia duration.

BACKGROUND: Fibrin D-dimer levels have been advocated as an useful clinical marker of thrombogenesis. HYPOTHESIS: We hypothesized that i) there is a hyperclotting state after the return of atrial fibrillation to sinus rhythm, ii) the measurement of plasma D-Dimer levels might be a good screening tool of this clotting status, and iii) the duration of arrhythmia influences the haemostasis measured by plasma D-Dimer levels. METHODS: Forty-two patients with atrial fibrillation undergoing cardioversion were divided into two groups: in Group A (n = 24,14 male, 56 +/- 11 years) the duration of atrial fibrillation was 72 hours or more (142.7 +/- 103.8 hours), in Group B (n = 18, 10 male, 61 +/- 13 years) the duration of atrial fibrillation was less than 72 hours (25 +/- 16 hours). Plasma fibrin D-dimer levels were measured by enzyme immunoassay before, and 36 hours after, cardioversion. The change of plasma D-dimer levels 36 hours after cardioversion was calculated as delta-D-dimer. RESULTS: There were no significant differences in demographic, clinical, and echocardiographic data, and the success of cardioversion between the two groups. Compared to the control, the baseline D-dimer levels were significantly higher in both groups. The delta D-dimer levels were significantly higher in Group A than in Group B (p < 0.005). Furthermore, plasma D-dimer levels 36 hours after cardioversion (r = 0.52, p = 0.0016) and delta-D-dimer levels (r = 0.73, p < 0.0001) showed significant correlations with the duration of atrial fibrillation. CONCLUSION: The longer duration of the atrial fibrillation episode could lead to a more prominent cardiovascular hyperclotting state after cardioversion, and the mean changes of plasma D-Dimer levels could be used as an useful clinical marker of the clotting state after atrial systole return.

Levosimendan use reduces matrix metalloproteinase-2 in patients with decompensated heart failure.

BACKGROUND: Extracellular matrix metabolism (ECM) has an important role in left ventricular (LV) remodeling in chronic heart failure (CHF). Matrix metalloproteinases (MMPs) are involved in the regulation of extracellular matrix (ECM) metabolism. We investigated the effect of levosimendan, a novel calcium sensitizer, on serum levels of MMP-2. METHODS: Our study population consisted of 60 consecutive patients with advanced heart failure who were admitted to hospital with an acute decompensation of their CHF. Patients were randomized to levosimendan (n = 30; 18 men, aged 65 +/- 3 years) or placebo (n = 30; 15 men, aged 67 +/- 4 years). Serum MMP-2 levels were assessed before and after treatment with levosimendan or placebo, using a commercially available ELISA. RESULTS: Serum levels of MMP-2 were reduced from 427 ng/ml 95%CI 372-484 to 371 ng/ml 95%CI 329-413 in the levosimendan treated group and from 433 ng/ml 95%CI 422-444 to 425 ng/ml 95%CI 414-436 in the placebo group. Repeated measurements ANOVA showed that treatment with levosimendan significantly affected levels of MMP-2 (p = 0.019). CONCLUSIONS: The present study showed that levosimendan may beneficially affect ECM remodeling in patients with acutely decompensated CHF. Whether these effects translate into added clinical benefits, as suggested by an improved ejection fraction in the levosimendan group, deserves further investigation.

Anti-inflammatory cytokine profile in acute coronary syndromes: behavior of interleukin-10 in association with serum metalloproteinases and proinflammatory cytokines.

BACKGROUND: The anti-inflammatory cytokine interleukin-10 (IL-10) downregulates the production of metalloproteinases (MMPs) and upregulates the production of their tissue inhibitors (TIMPs). The aim of this study was to assess the levels of IL-10 in patients with acute myocardial infarction (AMI) and unstable angina (UA), as well as to investigate the relationship of circulating IL-10 with the levels of MMPs (MMP-1, -2, -9), their tissue inhibitor (TIMP-1), pro-inflammatory cytokines (IL-6, tumor necrosis factor (TNF)-alpha) and serum lipids in the same patient population. METHODS: Serum MMP-1, -2, -9, TIMP-1, IL-6, TNF-alpha and IL-10 were measured by ELISA assays in 23 patients with AMI and 20 patients with UA after their hospital admission, as well as in 16 healthy controls subjects. The lipid profile was assessed by measuring the serum levels of total cholesterol, HDL-cholesterol, LDL-cholesterol and triglycerides. RESULTS: AMI patients exhibited significantly higher serum levels of IL-10 as compared with those of UA patients and healthy controls (both P=0.005). In contrast, there was no significant difference in IL-10 levels between UA patients and healthy controls. In AMI patients there was a statistically significant positive correlation of serum IL-10 with the levels of MMP-9 (rho=0.588, P=0.003), IL-6 (rho=0.502, P=0.015) and HDL-cholesterol (rho=0.697, P<0.001), as well as a significant negative correlation with the levels of triglycerides (rho=-0.417, P=0.048). CONCLUSIONS: Our results suggest that UA is associated with low serum activity of IL-10, while a significant elevation of this anti-inflammatory cytokine accompanies the peripheral immune responses of AMI. This observation indicates that different patterns of inflammatory reactions are implicated in the pathophysiology of two clinical conditions.

Atrial fibrillation and hypercoagulability: dependent on clinical factors or/and on genetic alterations?

UNLABELLED: It is well known that atrial fibrillation is associated with high incidence of thromboembolic events, propably due to a prothrombotic or hypercoagulable state. However, it is unclear whether or not there is any difference of this prothrombotic state in the clinical subgroups of atrial fibrillation patients, that is, in those with paroxysmal, persistent or permanent atrial fibrillation. From the other side the role of the arrhythmia duration on the changes of coagulative variables in atrial fibrillation patients is not clearly enough. The contribution of genetic and functional alterations in factors of the coagulation and fibrinolytic pathways (that is hemostatic risk factors) to the development of hypercoagulation state in atrial fibrillation requires clarification. We investigated therefore (1) if there are differences in the prothrombotic state between patients with different clinical status of the arrhythmia, (2) if the arrhythmia duration per se could be an independent determinant of the prothrombotic state in all atrial fibrillation patients and (3) if coexistent genetic alterations in haemostatic risk factors in patients with atrial fibrillation could contribute to the development of prothrombotic abnormalities. METHODS: Over a period of 23 months, we studied 55 patients with chronic non-valvular atrial fibrillation. We recruited 18 consecutive patients (13 men, mean age 59 +/- 10 years) with paroxysmal atrial fibrillation 17 patients (11 men, mean age 61 +/- 7 years) with persistent atrial fibrillation who underwent elective successful DC and remained in sinus rhythm at the 3 month visit and 20 patients (14 men mean age 64 +/- 9) with permanent atrial fibrillation. Blood results were compared to 17 age-sex- and race-matched controls. The prothrombotic state was quantified by measurement of plasma levels of fibrinogen, soluble P -selectin (an index of platelet activation) and von Willebrand factor (a marker of endothelial dysfunction). We assessed the frequencies of factor V Leiden and prothrombin variant G20210A to determine whether particular inherited haemostatic risk factors may have contribution to the development of prothrombotic state in atrial fibrillation patients. RESULTS: Permanent atrial fibrillation was associated with significant raised levels of von Willebrand factor, fibrinogen levels and soluble P -selectin compared to matched controls (all p < 0.001) and matched patients with paroxysmal and permanent AF (all p ranged between <0.003 and <0.002). Patients with persistent atrial fibrillation had significantly elevated von Willebrand factor levels (p = 0.0064) and fibrinogen levels (p = 0.002), but not Soluble P -selectin (p = 0.509). when compared to controls. Patients with paroxysmal atrial fibrillation had significantly elevated levels of P -selectin (p = 0.005) and fibrinogen (p = 0.003), but not von Willebrand factor (p =.0.61) compared to controls. Stepwise multiple regression analyses demonstrated that the arrhythmia duration (approximately 3 years) was an independent predictor of abnormal von Willebrand factor, fibrinogen and soluble P -selectin levels. Restoration of sinus rhythm in paroxysmal atrial fibrillation subgroup and successful electrical cardioversion of patients with permanent fibrillation atrial fibrillation did not significantly alter levels of the affected factors. The frequency of factor V Leiden was 8.9 in all studied patients with atrial fibrillation, versus 2.4% in the control group (odds ratio [OR] 4.6 [95% confidence (CI) 1.4-17.5], p = 0.02). The frequency of the prothrombin variant G20210A was 6.4.% compared with control group 1.6% (OR 4.9 [95% confidence interval (CI) 1.2-2.9], p = 0.04). There was a trend towards an increased frequency of factor V Leiden and/or prothrombin variant G20210A in patients age <55 years and in patients living at a particular area of Thrace mountains. CONCLUSIONS: Our results showed that there were significant differences in the prothrombotic state when patients with paroxysmal, and persistent atrial fibrillation were compared to matched that there were significant differences in the prothrombotic state when patients with paroxysmal, and persistent atrial fibrillation were compared to matched patients with permanent atrial fibrillation and controls in sinus rhythm. The duration of the arrhythmia (about 3 years) was an independent predictor of abnormal measured factors. We found for the first time that some genetic alterations in haemostatic risk factors could be coexist in atrial fibrillation patients and may be a contributor to the development of hypercoagulability in atrial fibrillation patients.