Do HMG-CoA reductase inhibitors affect fibrinogen?

The role of 3-hydroxy-3-methylglutaryl coenzyme a reductase inhibitors (statins) in modern rheumatology

Inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase commonly known as statins are widely used for treating hypercholesterolemia. However, there is much evidence to suggest that statins may have other properties in addition to their cholesterol-lowering effect. In particular, statins may neutralize post-translational prenylation of vitally important regulatory small GTPases, which are involved in several processes such as tissue fibrosis, cell maturation, apoptosis, immune cell maturation, and immune response. The beneficial effect of statins has been reported in animal and in vitro models as well as in some clinical studies. As they have an acceptable safety profile, statins may be considered, in selected cases, as a valuable concomitant therapy in the treatment of rheumatic and autoimmune disorders.

Effects of HMG-CoA reductase inhibitors on coagulation and fibrinolysis processes

Recent large clinical trials have demonstrated that HMG-CoA reductase inhibitors, or statins, markedly reduce morbidity and mortality when used in the primary and secondary prevention of cardiovascular disease. It has been established that the benefits of statin therapy in cardiovascular disease can be explained not only by the lipid-lowering potential of statins but also by nonlipid-related mechanisms (so-called "pleiotropic effects") that contribute to the positive effect of statins on the incidence of cardiovascular events. The coagulation and fibrinolytic systems are two separate but reciprocally linked enzyme cascades that regulate the formation and breakdown of fibrin. Numerous studies have demonstrated that disturbances of coagulation and fibrinolysis contribute to the development and progression of atherosclerosis, and that they affect the incidence of atherosclerosis-related clinical events. High plasma levels or activities of fibrinogen, factor VII, factor VIII, von Willebrand factor (vWF), soluble thrombomodulin, tissue plasminogen activator (tPA) and plasminogen activator inhibitor-1 (PAI-1) are thought to be associated with increased morbidity and mortality related to cardiovascular disease. Experimental studies and many clinical studies have recently shown that statins produce favourable effects on haemostatic parameters, including those that are risk factors for cardiovascular disease. Statins diminish procoagulant activity, which is observed at different stages of the coagulation cascade, including tissue factor (TF) activity, conversion of prothrombin to thrombin and thrombin activity. In some studies, statins also reduced fibrinogen levels. By altering the levels and activities of tPA and PAI-1, statins seem to stimulate fibrinolysis. The data on the effects of combined treatment with statins and other drugs on haemostasis are rather limited. They suggest that statins combined with fibric acid derivatives, omega-3 fatty acids and 17beta-estradiol are superior to statins alone. The only two clinical studies performed in patients with acute coronary syndromes showed a relatively weak effect of statins on haemostasis in those patients. Although various statins may produce different effects on individual variables, there are no convincing data showing that differences in their physicochemical and pharmacokinetic properties significantly alter their net effect on excessive procoagulant activity. Apart from the lipid-lowering effect, statins suppress the synthesis of several important nonsterol isoprenoids derived from the mevalonate pathway, especially farnesyl and geranylgeranyl pyrophosphates, which via enhanced protein prenylation, are involved in the regulation of many cellular processes. It is presumed that the inhibitory effect of statins on the mevalonate pathway is involved in the regulation of some key steps of coagulation and fibrinolysis processes. In this way they probably regulate the synthesis of TF, tPA and PAI-1, and perhaps they also control the generation and activity of thrombin. The beneficial effects of statins on coagulation and fibrinolysis may be responsible for their ability to decrease the number of cardiovascular events. The lipid-independent effects of statins on haemostasis may contribute to the marked decrease in the incidence rates of mortality, hospitalisation and revascularisation in patients treated with these drugs.

The combination of nebivolol plus pravastatin is associated with a more beneficial metabolic profile compared to that of atenolol plus pravastatin in hypertensive patients with dyslipidemia: a pilot study

Nebivolol, a selective beta1-lipophilic blocker, achieves blood pressure control by modulating nitric oxide release in addition to b-blockade. This dual mechanism of action could result in minimum interference with lipid metabolism compared to atenolol, a classic beta1-selective blocker. Hypertensive patients commonly exhibit lipid abnormalities and frequently require statins in combination with the anti-hypertensive therapy. We conducted this trial in order to clarify the effect on the metabolic profile of beta-blocker therapy with atenolol or nebivolol alone, or in conjunction with pravastatin. Thirty hypertensive hyperlipidemic men and women (total cholesterol >240 mg/dL [6.2 mmol/L], low-density lipoprotein cholesterol >190 mg/dL [4.9 mmol/L], triglycerides <500 mg/dL [5.6 mmol/L]) were separated in two groups. One group consisted of 15 subjects on atenolol therapy (50 mg daily), and the other group included 15 subjects on nebivolol therapy (5 mg daily). After 12 weeks of beta-blocker therapy, pravastatin (40 mg daily) was added in both groups for another 12 weeks. Atenolol significantly increased triglyceride levels by 19% (P=.05), while nebivolol showed a trend to increase high-density lipoprotein cholesterol by 8% (NS) and to decrease triglyceride levels by 5% (NS). Atenolol significantly increased lipoprotein(a) by 30% (P=.028). Fibrinogen levels were equally and not significantly decreased in both groups by 9% and 7%, respectively. Furthermore, atenolol and nebivolol decreased serum high-sensitivity C-reactive protein levels by 14% (P=.05) and 15% (P=.05), respectively. On the other hand, both atenolol and nebivolol showed a trend to increase homocysteine levels (NS) by 13% and 11%, respectively. Although uric acid levels remained the same, atenolol significantly increased the fractional excretion of uric acid by 33% (P=.03). Following nebivolol administration, glucose levels remained the same, while insulin levels were reduced by 10% and the HOMA index (fasting glucose levels multiplied by fasting insulin levels and divided by 22.5) was reduced by 20% (P=.05). There were no significant differences between the two patient groups in the measured parameters after the administration of beta-blockers, except for triglycerides (P<.05) and the HOMA index (P=.05). The addition of pravastatin to all patients (n=30) decreased total cholesterol by 21% (P<.001), low-density lipoprotein cholesterol by 28% (P<.001), apolipoprotein-B by 22% (P<.001), apolipoprotein-E by 15% (P=.014) and lipoprotein(a) levels by 12% (P=.023). Moreover, homocysteine levels and C-reactive protein were reduced by 17% (P=.05) and 43% (P=.05), respectively. We conclude that nebivolol seems to be a more appropriate therapy in hypertensive patients with hyperlipidemia and carbohydrate intolerance. Finally, the addition of pravastatin could further correct the well-established predictors of cardiovascular events.

Hemostatic effects of atorvastatin versus simvastatin

OBJECTIVE

To compare the effects of simvastatin and atorvastatin on hemostatic parameters.

METHODS

Sixty-one patients with primary hypercholesterolemia without coronary heart disease were treated with atorvastatin 10-20 mg/d or simvastatin 10-20 mg/d. At baseline, 4, 12, and 24 weeks, lipid levels such as low-density lipoprotein cholesterol (LDL-C), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), very-low-density lipoprotein cholesterol (VLDL-C), triglycerides (TGs), and hemostatic parameters such as platelet counts, partial thromboplastin time (PTT) prothrombin time (PT), and fibrinogen levels were measured.

RESULTS

At 12 weeks, the doses of the statins were increased to 20 mg/d in 10 of 35 (28.5%) patients treated with atorvastatin and 18 of 26 (69.2%) patients treated with simvastatin when the target level of LDL-C (130 mg/dL) was not reached. Mean doses were atorvastatin 12.8 mg/d and simvastatin 16.9 mg/d. After 24 weeks, 5 patients (14.3%) in the atorvastatin group and 4 patients (15.3%) in the simvastatin group had not reached the goal. In patients with diabetes, target level (LDL-C <100 mg/dL) was not reached in 35.7% of patients in the atorvastatin group and 44.4% of patients in the simvastatin group. Both simvastatin and atorvastatin were effective in lowering TC and LDL-C levels (p < 0.001). Atorvastatin lowered TGs significantly (p < 0.01). Neither atorvastatin nor simvastatin significantly reduced VLDL-C levels. HDL-C levels increased with atorvastatin, but there was no significant difference between the 2 groups. Platelet counts decreased with both statins nonsignificantly. Moreover, fibrinogen levels decreased with simvastatin and atorvastatin, but these reductions were significant only for simvastatin (p < 0.05). We detected prolongation of the PT with both drugs (p < 0.05); however, prolongation of the PTT was significant only with simvastatin (p < 0.001). Effectiveness of both statins on lipid and hemostatic parameters was dose related. Adverse effects were seen in 5 patients (14.2%) treated with atorvastatin and 3 patients (11.5%) treated with simvastatin. Elevations in serum transaminase levels >3 times the upper limit of normal and in creatine phosphokinase >5 times the upper limit of normal were not observed in any group.

CONCLUSIONS

Atorvastatin was more effective than simvastatin on lipid parameters, although statistically insignificantly, while simvastatin produced more significant changes than atorvastatin on hemostatic parameters. The mean dose of simvastatin was greater than that of atorvastatin. Both statins had increased effects on lipid and hemostatic parameters when doses were increased. Atorvastatin and simvastatin were well tolerated. Different effects of statins on lipid levels and on coagulation parameters should be considered in patients with hypercholesterolemia and tendency to coagulation, especially in preventing thrombotic events. Further studies in larger trials are needed to confirm these observations.

[Chronic Chlamydia pneumoniae infection in patients with coronary disease. Relation with increased fibrinogen values]

BACKGROUND

A number of studies have suggested that infection with Chlamydia pneumoniae can play a role in development of atherosclerosis. The goal of this study was to know the prevalence of chronic C. pneumoniae infection, evaluated with IgG antibodies seropositivity, in Spanish patients with coronary disease and its association with inflammatory markers and cardiovascular risk factors.

PATIENTS AND METHOD

In 176 patients with coronary disease IgG and IgM antibodies to C. pneumoniae were determined by enzyme immunoassay. In addition, fibrinogen and C-reactive protein values were measured as inflammatory markers. Controls were 55 healthy subjects whose age was not different from patients. Seropositivity for C. pneumoniae was considered when indices of IgG and/or IgM antibodies were higher than mean plus two standard deviations of control values. Three patients with seropositivity for IgM were excluded.

RESULTS

In 126 patients and 2 controls a seropositivity against C. pneumoniae was proved (72.8% vs 4.2%; p < 0.001). Cardiovascular risk factors were not different in seropositive and seronegative groups of patients. Prevalence of hyperfibrinogenemia was higher in the former group (38.8% vs 19.1%; p = 0.01). The number of the patients with increased values of C-reactive protein was similar in both groups, although these values could be modified by treatment with statins. In multivariate analysis an association between seropositivity for C. pneumoniae and hyperfibrinogenemia was found (odds ratio [OR] = 2.42; 95% confidence interval, 1.07-5.48; p = 0.03) after adjusting for age, gender, smoking, hypertension, hypercholesterolemia and diabetes.

CONCLUSIONS

Chronic infection with C. pneumoniae in patients with coronary disease is very prevalent, and it is associated with increased fibrinogen values.

Early statin therapy for acute coronary syndromes

OBJECTIVE

To review the clinical benefit of statins in the early management of acute coronary syndromes (ACSs) and their possible mechanisms of benefit.

DATA SOURCES

A MEDLINE search (1966-September 2001) was conducted using the following terms: pravastatin, lovastatin, simvastatin, atorvastatin, cerivastatin, fluvastatin, statins, hydroxymethylglutaryl coenzyme A reductase inhibitor, acute coronary syndromes, unstable angina, and myocardial infarction. Pertinent articles referenced in these publications were also reviewed.

STUDY SELECTION AND DATA EXTRACTION

French- and English-language human and animal studies were selected and analyzed.

DATA SYNTHESIS

In addition to their lipid-lowering properties, statins produce several nonlipid-related properties. These pleiotropic properties include improved endothelial function, reduction of inflammation at the site of the atherosclerotic plaque, inhibition of platelet aggregation, and anticoagulant effects, all of which may result in clinical benefit during ACSs. Preliminary studies and retrospective analyses of large clinical trials support the hypothesis that statins may be of benefit in ACSs. A recently published randomized, double-blind, multicenter trial evaluated the clinical impact of high-dose atorvastatin in patients with ACSs. Use of atorvastatin resulted in a decrease in a combined endpoint of cardiovascular events. Furthermore, initiation of statin therapy during hospitalization improves long-term compliance and may significantly improve clinical outcome.

CONCLUSIONS

Early use of statins in ACSs appears to decrease cardiovascular events. We believe statin therapy should be initiated early (at the latest before hospital discharge) in all patients who have been hospitalized for ACSs. Ongoing studies will clarify the benefit of these agents in ACSs, the importance of their nonlipid-lowering properties, and the optimal cholesterol-target concentrations.

Effect of ciprofibrate on C-reactive protein and fibrinogen levels

Statins can lower the circulating levels of C reactive protein (CRP). This effect may be relevant because CRP is a predictor of vascular risk. In contrast, the evidence that fibrates lower CRP levels is very limited. The effect of treatment with ciprofibrate (100 mg once daily) was investigated for 8 weeks in 30 patients with primary dyslipidemia. There was a significant (p < 0.01) decrease in median (range) CRP levels by 36.8% from 1.9 mg/L (1.0-6.0 mg/L) to 1.2 mg/L (1.0-5.5 mg/L). Plasma fibrinogen levels were also significantly (p = 0.05) reduced. There was no correlation between the fall in CRP levels and the changes in lipid or fibrinogen levels. These findings support the concept that fibrates, like the statins, lower serum CRP levels. However, fibrates have a different mode of action. Fibrates (with the exception of gemfibrozil) also consistently lower plasma fibrinogen levels. In contrast, the effect of statins on the circulating levels of this coagulation factor remains to be defined. These differences may help in defining the mechanisms responsible for drug-induced changes in the circulating levels of CRP and fibrinogen. A favorable effect on CRP and fibrinogen levels may increase the clinical efficacy of statins and fibrates.