Maria Benedetta Donati

Parenteral Anticoagulants: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition)

This chapter describes the pharmacology of approved parenteral anticoagulants, including the indirect anticoagulants, unfractionated heparin (UFH), low-molecular-weight heparins (LMWHs), fondaparinux, and danaparoid as well as the direct thrombin inhibitors hirudin, bivalirudin, and argatroban. UFH is a heterogeneous mixture of glycosaminoglycans that bind to antithrombin via a unique pentasaccharide sequence and catalyze the inactivation of thrombin factor Xa and other clotting factors. Heparin also binds to cells and other plasma proteins, endowing it with unpredictable pharmacokinetic and pharmacodynamic properties, and can lead to nonhemorrhagic side effects, such as heparin-induced thrombocytopenia (HIT) and osteoporosis. LMWHs have greater inhibitory activity against factor Xa than thrombin and exhibit less binding to cells and proteins than heparin. Consequently, LMWH preparations have more predictable pharmacokinetic and pharmacodynamic properties, have a longer half-life than heparin, and have a lower risk of nonhemorrhagic side effects. LMWHs can be administered once or twice daily by subcutaneous injection, without anticoagulant monitoring. Based on their greater convenience, LMWHs have replaced UFH for many clinical indications. Fondaparinux, a synthetic pentasaccharide, catalyzes the inhibition of factor Xa, but not thrombin, in an antithrombin-dependent fashion. Fondaparinux binds only to antithrombin; therefore, HIT and osteoporosis are unlikely to occur. Fondaparinux has excellent bioavailability when administered subcutaneously, has a longer half-life than LMWHs, and is given once daily by subcutaneous injection in fixed doses, without anticoagulant monitoring. Three parenteral direct thrombin inhibitors and danaparoid are approved as alternatives to heparin in HIT patients.

Meta-Analysis of Wine and Beer Consumption in Relation to Vascular Risk

Background—Many epidemiological studies have evaluated whether different alcoholic beverages protect against cardiovascular disease. We performed a meta-analysis of 26 studies on the relationship between wine or beer consumption and vascular risk. Methods and Results—General variance-based method and fitting models were applied to pooled data derived from 26 studies that gave a quantitative estimation of the vascular risk associated with either beverage consumption. From 13 studies involving 209 418 persons, the relative risk of vascular disease associated with wine intake was 0.68 (95% confidence interval, 0.59 to 0.77) relative to nondrinkers. There was strong evidence from 10 studies involving 176 042 persons to support a J-shaped relationship between different amounts of wine intake and vascular risk. A statistically significant inverse association was found up to a daily intake of 150 mL of wine. The overall relative risk of moderate beer consumption, which was measured in 15 studies involving 208 036 persons, was 0.78 (95% confidence interval, 0.70 to 0.86). However, no significant relationship between different amounts of beer intake and vascular risk was found after meta-analyzing 7 studies involving 136 382 persons. Conclusions—These findings show evidence of a significant inverse association between light-to-moderate wine consumption and vascular risk. A similar, although smaller association was also apparent in beer consumption studies. The latter finding, however, is difficult to interpret because no meaningful relationship could be found between different amounts of beer intake and vascular risk.

The −174G/C Interleukin-6 Polymorphism Influences Postoperative Interleukin-6 Levels and Postoperative Atrial Fibrillation. Is Atrial Fibrillation an Inflammatory Complication?

Background—It has been suggested that inflammation can have a role in the development of atrial arrhythmias after cardiac surgery and that a genetic predisposition to develop postoperative complications exists. This study was conceived to verify if a potential genetic modulator of the systemic inflammatory reaction to cardiopulmonary bypass (the −174 G/C polymorphism of the promoter of the Interleukin-6 gene) has a role in the pathogenesis of postoperative atrial fibrillation (AF). Patients and Results—In 110 primary isolated coronary artery bypass patients the −174G/C Interleukin-6 promoter gene variant was determined. Interleukin-6, fibrinogen and C-reactive protein plasma levels were determined preoperatively, 24, 48, and 72 hours after surgery and at discharge. Heart rate and rhythm were continuously monitored for the first 36 to 48 hours; daily 12-lead electrocardiograms were performed thereafter until discharge. GG, CT, and CC genotypes were found in 62, 38, and 10 patients, respectively. Multivariate analysis (which included genotype, age, sex, and classical risk factors for AF) identified the GG genotype as the only independent predictor of postoperative AF. The latter occurred in 33.9% of GG versus 10.4% of non-GG patients (hazard ratio 3.25, 95%CI 1.23 to 8.62). AF patients had higher blood levels of Interleukin-6 and fibrinogen after surgery (P <0.001 for difference between the area under the curve). Conclusion—The −174G/C Interleukin-6 promoter gene variant appears to modulate the inflammatory response to surgery and to influence the development of postoperative AF. These data suggest an inflammatory component of postoperative atrial arrhythmias and a genetic predisposition to this complication.

Polymorphisms in the Coagulation Factor VII Gene and the Risk of Myocardial Infarction

BACKGROUND High blood levels of coagulation factor VII are associated with a risk of ischemic vascular disease. Although factor VII levels may be genetically determined, the relation between genetic polymorphisms of factor VII, factor VII blood levels, and the risk of myocardial infarction has not been established. METHODS We performed a case-control study of 165 patients with familial myocardial infarction (mean [+/-SD] age, 55+/-9 years) and 225 controls without a personal or family history of cardiovascular disease (mean age, 56+/-8 years). The polymorphisms involving R353Q and hypervariable region 4 of the factor VII gene were studied. Factor VII clotting activity and antigen levels were also measured. RESULTS Patients with the QQ or H7H7 genotype had a decreased risk of myocardial infarction (odds ratios, 0.08 [95 percent confidence interval, 0.01 to 0.9] and 0.22 [95 percent confidence interval, 0.08 to 0.63], respectively). For the R353Q polymorphism, the RR genotype was associated with the highest risk, followed by the RQ genotype and then by the QQ genotype (P<0.001). For the polymorphism involving hypervariable region 4, the combined H7H5 and H6H5 genotypes were associated with the highest risk, followed in descending order by the H6H6, H6H7, and H7H7 genotypes (P<0.001). Patients with the QQ or H7H7 genotype had lower levels of both factor VII antigen and factor VII clotting activity than those with the RR or H6H6 genotype. Patients with the lowest level of factor VII clotting activity had a lower risk of myocardial infarction than those with the highest level (odds ratio, 0.13; 95 percent confidence interval, 0.05 to 0.34). CONCLUSIONS Our findings suggest that certain polymorphisms of the factor VII gene may influence the risk of myocardial infarction. It is possible that this effect may be mediated by alterations in factor VII levels.

Alcohol Consumption and Mortality in Patients With Cardiovascular Disease. A Meta-Analysis

OBJECTIVES The purpose of this study was to quantify the relation between alcohol consumption and cardiovascular and total mortality in patients with a history of cardiovascular events. BACKGROUND Regular, moderate alcohol consumption by healthy people is associated with lower cardiovascular and all-cause mortality. No extensive meta-analysis is presently available on the possible association of alcohol consumption with secondary events in patients with cardiovascular disease. METHODS Articles were retrieved through October 2009 by search in PubMed and EMBASE. Fifty-four publications were identified, but only 8 were selected for our analyses, including 16,351 patients with a history of cardiovascular disease. Secondary events were cardiovascular or all-cause mortality. All selected studies were prospective. Data were pooled with a weighted, least-squares regression analysis of second-order fractional polynomial models. RESULTS The meta-analysis on cardiovascular mortality showed a J-shaped pooled curve with a significant maximal protection (average 22%) by alcohol at approximately 26 g/day. In the meta-analysis on mortality for any cause, J-shaped pooled curves were observed in the overall analysis (average maximal protection of 18% in the range of 5 to 10 g/day) and in all subgroups according to either the type of patients or the characteristics of the studies. CONCLUSIONS In patients with cardiovascular disease, light to moderate alcohol consumption (5 to 25 g/day) was significantly associated with a lower incidence of cardiovascular and all-cause mortality.

Relation of the -174 G/C polymorphism of interleukin-6 to interleukin-6 plasma levels and to length of hospitalization after surgical coronary revascularization.

Interleukin (IL)-6 plasma levels are predictive of major cardiovascular events. The -174 G/C promoter polymorphism of the IL-6 gene affects basal levels in vivo and transcription rates in vitro, but its association with IL-6 acute phase levels among patients with coronary artery disease has not been investigated. In 111 patients with multivessel coronary artery disease undergoing elective coronary artery bypass graft surgery, we prospectively assessed genotype at position -174 and serial blood levels of IL-6 and other inflammatory indexes. Clinical and surgical characteristics did not differ among genotypic groups. IL-6 levels--measured daily up to 72 hours before surgery, after surgery, and at discharge--showed a mean 17-fold increase, peaking at 24 hours (p <0.0001). IL-6 levels (but not fibrinogen, white-blood cell count, and C-reactive protein values) differed significantly according to the -174 genotype (p = 0.042 for difference between areas under the curve), the 62 GG homozygotes exhibiting higher concentrations than the 49 carriers of the C allele (widest difference at 48 hours, p = 0.015 in multivariate analysis). GG homozygosity was associated with longer stays in the intensive care unit (2.5 +/- 3.4 vs 1.4 +/- 0.9 days, p = 0.02) and in the hospital (6.7 +/- 4.0 vs 5.3 +/- 1.4 days, p = 0.02) than C carriership. Rates of postoperative death, myocardial infarction, and stroke were 8% in GG homozygotes and 2% in C-carriers (p = 0.16). The IL-6-174 GG genotype is associated with higher acute phase levels of IL-6 and with longer stays in the hospital and in the intensive care unit than C allele carriership after surgical coronary revascularization.

Cancer and Thrombosis

Thrombosis is the most frequent complication and the second cause of death in patients with overt malignant disease. Increasing evidence suggests that thrombotic episodes may also precede the diagnosis of cancer by months or years thus representing a potential marker for occult malignancy. Recently, emphasis has been given to the potential risk of cancer therapy (both surgery and chemotherapy) in enhancing the risk for thromboembolic disease. Post-operative deep vein thrombosis is indeed more frequent in patients operated for malignant diseases than for other disorders. On the other hand, both chemotherapy and hormone therapy are associated with an increased thrombotic risk, which can be prevented by low-dose oral anticoagulation. Possible contributory causes for thromboembolic disease in cancer include the capacity of tumor cells and their products to interact with platelets, clotting and fibrinolytic systems, as well as their interactions with endothelial cells and tumor-associated macrophages. Cytokine release, acute phase reaction and neovascularization may contribute, in cancer patient, to in vivo clotting activation, which is well documented by several plasmatic markers of an hypercoagulable state. Last but not least, a direct pathogenetic role of clotting activation in the progression of malignancy has been repeatedly proposed on the basis of pharmacological studies with anticoagulant/fibrinolytic drugs in experimental animals and selected clinical malignancies, as well as, lately, in genetically modified animal models (e.g. mice transgenic for PAI-1).

Long Pentraxin PTX3 Upregulates Tissue Factor Expression in Human Endothelial Cells: A Novel Link Between Vascular Inflammation and Clotting Activation

Inflammation is a major contributing factor to atherosclerotic plaque development and ischemic heart disease. PTX3 is a long pentraxin that was recently found to be increased in patients with acute myocardial infarction. Because tissue factor (TF), the in vivo trigger of blood coagulation, plays a dominant role in thrombus formation after plaque rupture, we tested the possibility that PTX3 could modulate TF expression. Human umbilical vein endothelial cells, incubated with endotoxin (lipopolysaccharide) or the inflammatory cytokines interleukin-1&bgr; and tumor necrosis factor-&agr;, expressed TF. The presence of PTX3 increased TF activity and antigen severalfold in a dose-dependent fashion. PTX3 exerted its effect at the transcription level, inasmuch as the increased levels of TF mRNA, mediated by the stimuli, were enhanced in its presence. The increase in mRNA determined by PTX3 originated from an enhanced nuclear binding activity of the transacting factor c-Rel/p65, which was mediated by the agonists and measured by electrophoretic mobility shift assay. The mechanism underlying the increased c-Rel/p65 activity resided in an enhanced degradation of the c-Rel/p65 inhibitory protein I&kgr;B&agr;. In the area of vascular injury, during the inflammatory response, cell-mediated fibrin deposition takes place. Our results suggest that PTX3, by increasing TF expression, potentially plays a role in thrombogenesis and ischemic vascular disease.

Modulation of haemostatic function and prevention of experimental thrombosis by red wine in rats: a role for increased nitric oxide production

The effects of ethyl alcohol and wine (red and white) on haemostatic parameters and experimental thrombosis were studied in rats; NO was evaluated as a possible mediator of these effects. We found that red wine (12% alcohol) supplementation (8.4±0.4 ml d−1 in drinking water, for 10 days) induced a marked prolongation of ‘template’ bleeding time (BT) (258±13 vs 132±13 s in controls; P<0.001), a decrease in platelet adhesion to fibrillar collagen (11.6±1.0 vs 32.2±1.3%; P<0.01) and a reduction in thrombus weight (1.45±0.33 vs 3.27±0.39 mg; P<0.01). Alcohol‐free red wine showed an effect similar to red wine. In contrast, neither ethyl alcohol (12%) nor white wine (12% alcohol) affected these systems. All these effects were also observed after red wine i.v. injection (1 ml kg−1 of 1 : 4 dilution) 15 min before the experiments. The effects of red wine were prevented by the NO inhibitor, Nωnitro‐L‐arginine‐methyl ester (L‐NAME). L‐arginine, not D‐arginine, reversed the effect of L‐NAME on red wine infusion. Red wine injection induced a 3 fold increase in total radical‐trapping antioxidant parameter values of rat plasma with respect to controls, while white wine and alcohol did not show any effect. Our study provides evidence that red wine modulates primary haemostasis and prevents experimental thrombosis in rats, independently of its alcohol content, by a NO‐mediated mechanism.

Failure of aspirin at different doses to modify experimental thrombosis in rats

Aspirin inhibits the synthesis of both platelet and vascular arachidonic acid metabolites which have opposite effects on platelet function. The rationale for its clinical use as an antithrombotic drug has therefore been questioned. Previous studies in rats indicated that platelets are more sensitive to aspirin than arterial tissues and are almost as sensitive as venous tissues. We have now assessed the effects of aspirin at various doses on an arterial and a venous model of experimentally-induced thrombosis. Aspirin at high doses (50–200 mg/kg b.w.) neither reduced nor potentiated the thrombosis tendency in either model. Lower doses (2.5–10 mg/kg b.w.) — which preferentially inhibited platelet prostaglandin formation — did not protect the animals against thrombosis. It is possible, on one hand, that the metabolic pathways of arachidonic acid which are blocked by aspirin do not play a crucial role in the models used. One the other hand, the difficulty to completely dissociate the inhibitory effects of aspirin on platelet and vascular prostaglandins could be crucial for the antithrombotic activity of this drug. The concept that, when administered in large doses, aspirin — by inhibiting vascular prostacyclin activity — potentiates experimental thrombosis, is not supported by the present study.