Anetta Undas

Anti-inflammatory effects of simvastatin in subjects with hypercholesterolemia

AIMS Beneficial effects of statins in preventing cardiovascular events may depend, at least in part, on their anti-inflammatory action. The aim of the study was to assess the influence of simvastatin and aspirin on serum levels of C-reactive protein (CRP), tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) in hypercholesterolemic subjects. METHODS AND RESULTS In 33 asymptomatic men with total cholesterol (TC) >6.5 mmol l(-1) and in 25 men with coronary heart disease and borderline-high cholesterol levels (between 5.2 and 6.5 mmol l(-1)) chronically treated with low-dose aspirin (75 mg/d), serum levels of CRP, TNF-alpha, IL-6, and IL-8 were determined before and after a 3-month simvastatin therapy (20-40 mg daily). In the former group, these markers of inflammation were also measured before and after a 2-week treatment with aspirin (300 mg/d), implemented prior to and in combination with simvastatin. A distinct reduction of CRP and TNF-alpha was found in both groups; IL-6 levels were decreased only in subjects with marked hypercholesterolemia. Aspirin had no effect on the anti-inflammatory action of simvastatin. CONCLUSIONS In men with hypercholesterolemia simvastatin treatment lowers serum levels of CRP and proinflammatory cytokines. Low-dose aspirin does not add to the anti-inflammatory action of simvastatin.

Inhibition of thrombin generation by simvastatin and lack of additive effects of aspirin in patients with marked hypercholesterolemia.

OBJECTIVES To assess the effects of aspirin compared with simvastatin on thrombin generation in hypercholesterolemic men, and to establish whether the reduction of elevated blood cholesterol by simvastatin would affect the action of aspirin on thrombin formation. BACKGROUND Aspirin inhibits thrombin formation, but its performance is blunted in hypercholesterolemia. By virtue of altering lipid profile, statins could be expected to influence thrombin generation. METHODS Thirty-three men, aged 34 to 61 years, with minimal or no clinical symptoms, serum total cholesterol >6.5 mmol/liter and serum triglycerides <4.6 mmol/liter, completed the study consisting of three treatment phases. First, they received 300 mg of aspirin daily for two weeks (phase I), which was then replaced by simvastatin at the average dose of 24 mg/d for three months (phase II). In phase III, aspirin, 300 mg/day, was added for two weeks to simvastatin, the dose of which remained unchanged. Thrombin generation was assessed: 1) in vivo, by measuring levels of fibrinopeptide A (FPA) and prothrombin fragment 1+2 (F1+2) in venous blood; and 2) ex vivo, by monitoring the rates of increase of FPA and F1+2 in blood emerging from standardized skin incisions of a forearm. A mathematical model was used to describe the kinetics of thrombin formation at the site of microvascular injury. RESULTS Two-week treatment with aspirin had no effect on thrombin markers in vivo, while ex vivo it depressed the total amount of thrombin formed, though not the reaction rate. After simvastatin treatment, serum cholesterol decreased by 31% and LDL cholesterol by 42%, while thrombin generation became markedly depressed. In venous blood, FPA was significantly reduced. Concomitantly, the initial thrombin concentration and total amount of thrombin generated decreased significantly. Addition of aspirin to simvastatin (phase III) had no further effect on any of these parameters. CONCLUSIONS In men with hypercholesterolemia, lowering serum cholesterol level by a three-month simvastatin treatment is accompanied by a marked reduction of thrombin generation both at basal conditions in venous blood and after activation of hemostasis by microvascular injury. Once blood cholesterol became reduced, adding aspirin to simvastatin did not enhance dampening of thrombin formation.

Incidence and predictors of coronary stent thrombosis: Evidence from an international collaborative meta-analysis including 30 studies, 221,066 patients, and 4276 thromboses

BACKGROUND Stent thrombosis remains among the most feared complications of percutaneous coronary intervention (PCI) with stenting. However, data on its incidence and predictors are sparse and conflicting. We thus aimed to perform a collaborative systematic review on incidence and predictors of stent thrombosis. METHODS PubMed was systematically searched for eligible studies from the drug-eluting stent (DES) era (1/2002-12/2010). Studies were selected if including ≥ 2000 patients undergoing stenting or reporting on ≥ 25 thromboses. Study features, patient characteristics, and incidence of stent thrombosis were abstracted and pooled, when appropriate, with random-effect methods (point estimate [95% confidence intervals]), and consistency of predictors was formally appraised. RESULTS A total of 30 studies were identified (221,066 patients, 4276 thromboses), with DES used in 87%. After a median of 22 months, definite, probable, or possible stent thrombosis had occurred in 2.4% (2.0%; 2.9%), with acute in 0.4% (0.2%; 0.6%), subacute in 1.1% (1.0%; 1.3%), late in 0.5% (0.4%; 0.6%), and very late in 0.6% (0.4%; 0.8%). Similar figures were computed for studies reporting only on DES. From a total of 47 candidate variables, definite/probable stent thrombosis was more commonly and consistently predicted by early antiplatelet therapy discontinuation, extent of coronary disease, and stent number/length, with acute coronary syndrome at admission, diabetes, smoking status, and bifurcation/ostial disease also proving frequent predictors, but less consistently. CONCLUSIONS Despite numerous possible risk factors, the most common and consistent predictors of stent thrombosis are early antiplatelet therapy discontinuation, extent of coronary disease, and stent number/length.

Effects of Polyunsaturated Omega-3 Fatty Acids on Responsiveness to Dual Antiplatelet Therapy in Patients Undergoing Percutaneous Coronary Intervention: The OMEGA-PCI (OMEGA-3 Fatty Acids After PCI to Modify Responsiveness to Dual Antiplatelet Therapy) Study

OBJECTIVES The purpose of this study was to investigate whether omega-3 polyunsaturated fatty acids (PUFAs) are able to modify platelet responsiveness to dual antiplatelet therapy in stable coronary artery disease patients undergoing percutaneous coronary intervention (PCI). BACKGROUND Although previous studies have suggested antiplatelet properties of omega-3 polyunsaturated fatty acids, it is unknown whether they can enhance platelet inhibition on standard aspirin and clopidogrel treatment. METHODS The OMEGA-PCI (OMEGA-3 Fatty Acids After PCI to Modify Responsiveness to Dual Antiplatelet Therapy) study was an investigator-initiated, prospective, single-center, double-blind, placebo-controlled, randomized study. Patients receiving standard dual antiplatelet therapy (aspirin 75 mg/day and clopidogrel 600 mg loading dose followed by 75 mg/day) were randomly assigned to receive the addition of 1 g of omega-3 ethyl esters (n = 33) or placebo (n = 30) for 1 month. Platelet function was measured serially by light transmission aggregometry (adenosine diphosphate and arachidonic acid [AA] were used as agonists) and assessment of the phosphorylation status of the vasodilator-stimulated phosphoprotein at baseline, 12 h, 3 to 5 days, and 30 days after randomization. RESULTS The P2Y(12) reactivity index was significantly lower, by 22.2%, after 1 month of treatment with omega-3 polyunsaturated fatty acids compared with placebo when used in addition to dual antiplatelet therapy (p = 0.020). Maximal platelet aggregation induced by 5 and 20 micromol/l adenosine diphosphate was lower by 13.3% (p = 0.026) and 9.8% (p = 0.029), respectively, after 1 month of treatment with omega-3 polyunsaturated fatty acids compared with placebo. Platelet aggregation after AA stimulation was low and did not change significantly throughout the study. There were no cases of aspirin resistance during follow-up that was suggestive of good compliance with the medication. CONCLUSIONS The addition of omega-3 ethyl esters to the combination of aspirin and clopidogrel significantly potentiates platelet response to clopidogrel after percutaneous coronary intervention.

Pathogenesis of vascular disease in hyperhomocysteinaemia

Elevated plasma homocysteine is an independent risk factor for atherosclerosis and thrombosis. The exact mechanism by which homocysteine exerts its atherothrombotic action is still unclear. Accumulating evidence suggests that hyperhomocysteinaemia leads to endothelial injury and dysfunction, mediated by free radicals generated during the oxidation of homocysteine. Homocysteine also stimulates the proliferation of vascular smooth-muscle cells and inhibits the growth of vascular endothelial cells. Elevated homocysteine levels may also promote thrombosis by increased generation of thrombin. Other possible mechanisms for homocysteine-mediated atherogenesis include: The altered methylation of DNA and altered regulatory proteins associated with cell membrane, decreased bioavailability of nitric oxide, increased elastolysis and collagen accumulation, overstimulation of N-methyl-D-aspartate receptors and excessive adhesion of monocytes and neutrophils to endothelium. Understanding the mechanisms in vivo by which hyperhomocysteinaemia is associated with vascular disease may provide new approaches to prevention and treatment of atherothrombosis. ∗∗∗J Cardiovasc Risk 5:239-247

Thrombin generation in acute coronary syndrome and stable coronary artery disease: dependence on plasma factor composition

Summary.  Background: Acute coronary syndrome (ACS) is associated with thrombin formation, triggered by ruptured or eroded coronary atheroma. We investigated whether thrombin generation based on circulating coagulation protein levels, could distinguish between acute and stable coronary artery disease (CAD). Methods and results: Plasma coagulation factor (F) compositions from 28 patients with ACS were obtained after onset of chest pain. Similar data were obtained from 25 age‐ and sex‐matched patients with stable CAD. All individuals took aspirin. Patients on anticoagulant therapy were excluded. The groups were similar in demographic characteristics, comorbidities and concomitant treatment. Using each individual’s coagulation protein composition, tissue factor (TF) initiated thrombin generation was assessed both computationally and empirically. TF pathway inhibitor (TFPI), antithrombin (AT), factor II (FII) and FVIII differed significantly (P < 0.01) between the groups, with levels of FII, FVIII and TFPI higher and AT lower in ACS patients. When thrombin generation profiles from individuals in each group were compared, simulated maximum thrombin levels (P < 0.01) and rates (P < 0.01) were 50% higher with ACS while the initiation phases of thrombin generation were shorter. Empirical reconstructions of the populations reproduced the thrombin generation profiles generated by the computational model. The differences between the thrombin generation profiles for each population were primarily dependent upon the collective contribution of AT, FII and FVIII. Conclusion: Simulations of thrombin formation based on plasma composition can discriminate between acute and stable CAD.

Fibrin clot properties in acute ischemic stroke: relation to neurological deficit

INTRODUCTION Hypercoagulable state occurs in patients with acute vascular events. We wondered whether clot structure/function is altered in acute ischemic stroke (AIS), like in acute myocardial infarction. PATIENTS AND METHODS In 45 consecutive patients with AIS (24M, 21F), aged 67.4+/-10.9 years, and 45 healthy controls matched for age and sex, we investigated plasma fibrin clot structure/function by permeation, turbidity, and efficiency of fibrinolysis. RESULTS Compared to controls, AIS patients produced clots that had 30.5% less porous network (p<0.0001), were less susceptible to fibrinolysis (10.8% longer lysis time, p=0.001), were 20.5% more compact (p<0.0001), had 17.1% higher clot mass (p<0.0001), and showed increased (by 10.2%) overall fiber thickness (p<0.0001) with 8% shorter lag phase of fibrin formation (p=0.0002). Maximum rate of D-dimer release from clots was similar. Multiple regression analyses for all subjects (n=90) showed that being a stroke patient (p<0.0001), fibrinogen (p<0.0001) and lipoprotein(a) (p=0.0075) were independent predictors of clot permeability (model R2 0.79). Only fibrinogen (p<0.0001) and lipoprotein(a) (p=0.0026) predicted lysis time. All other fibrin parameters were predicted only by being a stroke patient. Clot compaction was associated with neurological deficit on admission (r=-0.81; p<0.0001) and at discharge (r=-0.69; p<0.0001). Patients with 0 or 1 point in the modified Rankin scale (n=19) had 13.3% higher clot permeability compared to the remainder (p=0.02). CONCLUSIONS This study is the first to show that AIS is associated with unfavorably altered fibrin clot properties that might correlate with neurological deficit.

Altered fibrin clot structure in patients with advanced coronary artery disease: a role of C‐reactive protein, lipoprotein(a) and homocysteine

Evidence for a role of fibrin clot structure/function in coronary artery disease (CAD) is scarce [1]. Factors that determine unfavorable fibrin clot properties in CAD patients are poorly understood. We have demonstrated that C-reactive protein (CRP) [2], lipoprotein(a) [Lp(a)] [3] and total homocysteine (tHcy) [4] are associated with decreased clot permeability and susceptibility to lysis. However, these findings are derived from small studies in patients aged< 60 years with a variable extent of CAD. The aim of the current study was to evaluate fibrin clot properties in middle-aged and elderly patients with advanced CAD. We studied 133 patients with angiographically proven CAD (‡ 70% stenosis), who qualified for elective coronary artery bypass grafting surgery. Exclusion criteria were: any acute illness; cancer; hepatic or renal dysfunction; anticoagulant therapy; acute coronary syndromewithin the previous 6 weeks; or previous venous thromboembolism. Medications were administered in unchanged doses for at least 2 weeks. Apparently healthy, ageand sex-matched individuals (n = 100) served as controls. Fibrinogen and high-sensitivity CRP were measured by nephelometry (Dade Behring, Marburg, Germany). Fasting plasma tHcy levels were measured using the IMX System (Abbott Diagnostics, Wiesbaden, Germany). Serum Lp(a) levels were determined by ELISA (Biopool, Umea, Sweden). Fibrin clot permeability, expressed as a permeation coefficient (Ks), which indicates the pore size, was determined as described [5]. Clot lysis times were determined using a turbidity assay with slight modifications. Citrated plasma was diluted with the Tris buffer, containing 20 mmol L CaCl2, 1 U mL –1

Letter by Undas and Jakubowski Regarding Article, “Relationship Between Homocysteine and Mortality in Chronic Kidney Disease”

To the Editor: We read with keen interest the article by Menon et al,1 which concluded that plasma total homocysteine (tHcy) is not a risk factor for all-cause or cardiovascular disease (CVD) mortality in patients with stage 3 and 4 chronic kidney disease (CKD). The conflicting results of other studies are explained by Menon et al by the failure to adjust for the kidney function. However, …

Lipoprotein(a) as a modifier of fibrin clot permeability and susceptibility to lysis.

Lipoprotein(a) [Lp(a)] is the unique lipoprotein particle with apolipoprotein(a) [apo(a)] bound to apoB by a disulfide linkage [1]. It has been demonstrated that elevated plasma Lp(a) is associated with cardiovascular disease [2]. Kringle domains of apo(a) are homologous with the kringle domains IV and V in the plasminogen molecule [1]. A varying number of type 2 kringles IV determines a heterogenous size of apo(a), with the smaller isoforms being the most pathogenic [3]. There is an inverse correlation between the number of KIV repeats and Lp(a) concentrations [1]. Apo(a) competes with plasminogen for fibrin(ogen) binding sites, resulting in the inhibition of clot lysis [4]. Very recently, in apo(a) transgenic mice, Sha et al. [5] have reported that apo(a) produces a marked prothrombotic effect by a mechanism independent of plasminogen. However, it is not known whether elevated Lp(a) levels and apo(a) isoforms can alter clot properties in human subjects. We studied two groups: (i) 52 apparently healthy men, aged 38–63 years (mean 50 years); and (ii) 24 male survivors of myocardial infarction (MI), aged 42–65 years (mean 51 years). Exclusion criteria were: diabetes; renal insufficiency; acute vascular event within the preceding 6 months; severe concomitant diseases. Healthy individuals and patients with MI (despite clear indications) did not take any medication at least 6 weeks prior to the enrolment. Lipid profile was measured by routine laboratory methods, and fibrinogen and C-reactive protein (CRP) by nephelometry (Dade Behring, Marburg, Germany). Lp(a) was determined using a commercial assay (American Diagnostica, Greenwich, CT, USA). To better evaluate the relationship between the fibrin clot properties and Lp(a), we evaluated two features of the apo(a) gene locus that appear to determine Lp(a) levels. The number of KIV repeats that affects Lp(a) particle size was determined by immunoblotting [6]. Genotyping of the apo(a) pentanucleotide polymorphism at position )1373 was performed as described previously [7]. Study groups were stratified by a dominant allele of the KIV polymorphism (£22 or >22 KIV repeats) to evaluate the effect of the apo(a) pentanucleotide polymorphism according to the study by Holmer et al. [8]. Fibrin clot permeation was determined in a pressure-driven tube system and expressed as a permeation coefficient (Ks), which indicates the pore size [9]. The kinetics of fibrin formation were evaluated by turbidimetry and a slope of the polymerization curve, along with maximum absorbancy, were recorded [9]. Fibrinolysis was evaluated bymeasuring the fibrin assembly kinetics by spectrophotometry upon addition of recombinant tissue plasminogen activator (rt-PA, Boerhinger Ingelheim, Ingelheim, Germany), along with thrombin [10] and the time required for a 50%decrease in clot turbidity (t50%) was a measure of the clot susceptibility to fibrinolysis. All measurements were performed in duplicate by an investigator blinded to the origin of samples. The intraindividual variabilities of results were 6–8%. Data are given as medians (95% confidence interval; CI) or otherwise stated. Inter-group comparisons were performed using the Mann–Whitney U-test and correlations were assessed by the Spearman test. Multiple linear regression analysis (the backward stepwise method) was used to determine predictors of Ks and t50%. A value of P < 0.05 was considered significant. Patients with MI had higher cholesterol, fibrinogen, and CRP levels than healthy subjects while other variables were similar (Table 1). Fibrin clot permeability was reduced and clot lysis, expressed by t50%, was slower inMI patients as compared with healthy individuals (Table 1). In MI patients, we also found lower maximum absorbancy of the clots than in healthy controls (Table 1). The median Lp(a) concentration was higher in patients than in healthy subjects (28.8 vs. 13.2 mg dL; P 1⁄4 0.002). In healthy individuals with a cutoff of Lp(a) Correspondence: Anetta Undas, Institute of Cardiology, Jagiellonian University School of Medicine, 80 Pradnicka Str., 31-022 Cracow, Poland. Tel.: +48 12 6143145; fax: +48 12 4233900; e-mail: mmundas@ cyf-kr.edu.pl