Changes induced by pravastatin treatment on hemostatic and fibrinolytic patterns in patients with type IIb hyperlipoproteinemia

Pravastatin for lowering lipids

BACKGROUND

A detailed summary and meta-analysis of the dose-related effect of pravastatin on lipids is not available.

OBJECTIVES

Primary objective To assess the pharmacology of pravastatin by characterizing the dose-related effect and variability of the effect of pravastatin on the surrogate marker: low-density lipoprotein (LDL cholesterol). The effect of pravastatin on morbidity and mortality is not the objective of this systematic review. Secondary objectives • To assess the dose-related effect and variability of effect of pravastatin on the following surrogate markers: total cholesterol; high-density lipoprotein (HDL cholesterol); and triglycerides. • To assess the effect of pravastatin on withdrawals due to adverse effects.

SEARCH METHODS

The Cochrane Hypertension Information Specialist searched the following databases for randomized controlled trials (RCTs) up to September 2021: CENTRAL (2021, Issue 8), Ovid MEDLINE, Ovid Embase, Bireme LILACS, the WHO International Clinical Trials Registry Platform, and ClinicalTrials.gov. We also contacted authors of relevant papers regarding further published and unpublished work. The searches had no language restrictions.

SELECTION CRITERIA

Randomized placebo-controlled trials evaluating the dose response of different fixed doses of pravastatin on blood lipids over a duration of three to 12 weeks in participants of any age with and without evidence of cardiovascular disease.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed eligibility criteria for studies to be included, and extracted data. We entered lipid data from placebo-controlled trials into Review Manager 5 as continuous data and withdrawal due to adverse effects (WDAEs) data as dichotomous data. We searched for WDAEs information from all trials. We assessed all trials using Cochrane's risk of bias tool under the categories of sequence generation, allocation concealment, blinding, incomplete outcome data, selective reporting, and other potential biases.

MAIN RESULTS

Sixty-four RCTs evaluated the dose-related efficacy of pravastatin in 9771 participants. The participants were of any age, with and without evidence of cardiovascular disease, and pravastatin effects were studied within a treatment period of three to 12 weeks. Log dose-response data over the doses of 5 mg to 160 mg revealed strong linear dose-related effects on blood total cholesterol and LDL cholesterol, and a weak linear dose-related effect on blood triglycerides. There was no dose-related effect of pravastatin on blood HDL cholesterol. Pravastatin 10 mg/day to 80 mg/day reduced LDL cholesterol by 21.7% to 31.9%, total cholesterol by 16.1% to 23.3%,and triglycerides by 5.8% to 20.0%. The certainty of evidence for these effects was judged to be moderate to high. For every two-fold dose increase there was a 3.4% (95% confidence interval (CI) 2.2 to 4.6) decrease in blood LDL cholesterol. This represented a dose-response slope that was less than the other studied statins: atorvastatin, rosuvastatin, fluvastatin, pitavastatin and cerivastatin. From other systematic reviews we conducted on statins for its effect to reduce LDL cholesterol, pravastatin is similar to fluvastatin, but has a decreased effect compared to atorvastatin, rosuvastatin, pitavastatin and cerivastatin. The effect of pravastatin compared to placebo on WADES has a risk ratio (RR) of 0.81 (95% CI 0.63 to 1.03). The certainty of evidence was judged to be very low.

AUTHORS' CONCLUSIONS

Pravastatin lowers blood total cholesterol, LDL cholesterol and triglyceride in a dose-dependent linear fashion. This review did not provide a good estimate of the incidence of harms associated with pravastatin because of the lack of reporting of adverse effects in 48.4% of the randomized placebo-controlled trials.

Statin therapy and lipoprotein(a) levels: a systematic review and meta-analysis

AIMS 

Lipoprotein(a) [Lp(a)] is a causal and independent risk factor for cardiovascular disease (CVD). People with elevated Lp(a) are often prescribed statins as they also often show elevated low-density lipoprotein cholesterol (LDL-C) levels. While statins are well-established in lowering LDL-C, their effect on Lp(a) remains unclear. We evaluated the effect of statins compared to placebo on Lp(a) and the effects of different types and intensities of statin therapy on Lp(a).

METHODS AND RESULTS 

We conducted a systematic review and meta-analysis of randomized trials with a statin and placebo arm. Medline and EMBASE were searched until August 2019. Quality assessment of studies was done using Cochrane risk-of-bias tool (RoB 2). Mean difference of absolute and percentage changes of Lp(a) in the statin vs. the placebo arms were pooled using a random-effects meta-analysis. We compared effects of different types and intensities of statin therapy using subgroup- and network meta-analyses. Certainty of the evidence was determined using GRADE (Grading of Recommendations, Assessment, Development, and Evaluation). Overall, 39 studies (24 448 participants) were included. Mean differences (95% confidence interval) of absolute and percentage changes in the statin vs. the placebo arms were 1.1 mg/dL (0.5-1.6, P < 0.0001) and 0.1% (-3.6% to 4.0%, P = 0.95), respectively (moderate-certainty evidence). None of the types of statins changed Lp(a) significantly compared to placebo (very low- to high-certainty evidence), as well as intensities of statin therapy (low- to moderate-certainty evidence).

CONCLUSION 

Statin therapy does not lead to clinically important differences in Lp(a) compared to placebo in patients at risk for CVD. Our findings suggest that in these patients, statin therapy will not change Lp(a)-associated CVD risk.

Influences of age, sex, and LDL-C change on cardiovascular risk reduction with pravastatin treatment in elderly Japanese patients: A post hoc analysis of data from the Pravastatin Anti-atherosclerosis Trial in the Elderly (PATE)

BACKGROUND

The Pravastatin Anti-atherosclerosis Trial in the Elderly (PATE) found that the prevalence of cardiovascular events (CVEs) was significantly lower with standard-dose (10-20 mg/d) pravastatin treatment compared with low-dose (5 mg/d) pravastatin treatment in elderly (aged ⩾ 60 years) Japanese patients with hypercholesterolemia. Small differences in on-treatment total cholesterol and low-density lipoprotein cholesterol (LDL-C) levels between the 2 dose groups in the PATE study were associated with significant differences in CVE prevalence. However, the reasons for these differences have not been determined. How sex and age differences influence the effectiveness of pravastatin also remains unclear.

OBJECTIVES

The aims of this study were to determine the relationship between reduction in LDL-C level and CVE risk reduction in the PATE study and to assess the effects of sex and age on the effectiveness of pravastatin treatment (assessed using CVE risk reduction).

METHODS

In this post hoc analysis, Cox regression analysis was performed to study the relationship between on-treatment (pravastatin 5-20 mg/d) LDL-C level and CVE risk reduction using age, sex, smoking status, presence of diabetes mellitus and/or hypertension, history of cardiovascular disease (CVD), and high-density lipoprotein cholesterol level as adjustment factors. To explore risk reduction due to unspecified mechanisms other than LDLrC reduction, an estimated Kaplan-Meier curve from the Cox regression analysis was calculated and compared with the empirical (observed) Kaplan-Meier curve.

RESULTS

A total of 665 patients (527 women, 138 men; mean [SD] age, 72.8 [5.7] years) were enrolled in PATE and were followed up for a mean of 3.9 years (range, 3-5 years). Of those patients, 50 men and 173 women were ⩾75 years of age. Data from 619 patients were included in the present analysis. In the calculation of model-based Kaplan-Meier curves, data from an additional 32 patients were excluded from the LDL-C analysis because there were no data on pretreatment LDL levels; hence, the data from 587 patients were analyzed. A reduction in LDL-C level of 20 mg/dL was associated with an estimated CVE risk reduction of 24.7% (hazard ratio [HR] = 0.753; 95% CI, 0.625-0.907; P = 0.003). Risk was reduced by 22.2% in patients aged <75 years (HR = 0.778; 95% CI, 0.598-1.013; P = NS) and 29.9% in patients aged ⩾75 years (HR = 0.701; 95% CI, 0.526-0.934; P = 0.015). The risk reductions were 19.8% in women (HR = 0.802; 95% CI, 0.645-0.996; P = 0.046) and 35.8% in men (HR = 0.642; 95% CI, 0.453-0.911; P = 0.013). The risk reduction was 32.4% in patients without a history of CVD at enrollment (HR = 0.676; 95% CI, 0.525-0.870; P = 0.002) and 15.1% in those with a history of CVD (HR = 0.849; 95% CI, 0.630-1.143; P= NS). The estimated Kaplan-Meier curve strongly suggested that the effects of pravastatin were only partially associated with changes in LDLrC level.

CONCLUSIONS

The results from this post hoc analysis suggest that pravastatin 5 to 20 mg/d might elicit CVE risk reduction by mechanisms other than cholesterol-lowering effects alone. They also suggest that pravastatin treatment might be effective in reducing the risk for CVEs in both female and male patients aged ⩾75 years.

Lipid and non-lipid effects of statins

Long- and short-term trials with the 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) have demonstrated significant reductions in cardiovascular events in patients with and without history of coronary heart disease. Statins are well-established low-density lipoprotein (LDL)-lowering agents, but their clinical benefit is believed to result from a number of lipid and non-lipid effects beyond LDL lowering, including a rise in plasma high-density lipoprotein levels. Beyond improving the lipid profile, statins have additional non-lipid effects including benefit on endothelial function, inflammatory mediators, intima-media thickening, prothombotic factors that ultimately result in plaque stabilization. These effects arise through the inhibition of several mevalonate-derived metabolites other than cholesterol itself, which are involved in the control of different cellular functions. Although statins represent the gold standard in the prevention and treatment of coronary heart disease, combination therapy with other lipid-lowering drugs, as well as novel therapeutic indications, may increase their therapeutic potential.

Reduced creatine kinase release with statin use at the time of myocardial infarction

BACKGROUND

Statin pre-treatment has been shown to reduce myocardial infarct size in animal models. We evaluated peak creatine kinase levels in humans based on concomitant or very early statin initiation following myocardial infarction.

METHODS

We identified 66 consecutive patients who received a statin within 24 h of admission to our coronary care unit for myocardial infarction. Each statin patient was matched with three patients who had not received statin therapy (n=198). Statin patients were subgrouped into those receiving statin therapy at the time of infarction (n=44) and those initiated on statin therapy within 24 h of infarction (n=22). Peak total creatine kinase concentrations were compared between groups. A linear regression model was developed to test for differences in peak creatine kinase after adjusting for differences between groups.

RESULTS

Patients receiving statin therapy within 24 h of admission had significantly smaller median peak creatine kinase concentrations compared to those not receiving a statin (416 IU/l [258, 992] vs. 699 IU/l [339, 1728]; p=0.020). Subgroup analysis revealed that the lower peak creatine kinase concentrations within the statin group were a result of lower creatine kinase concentrations in those patients on a statin at the time of myocardial infarction (399 IU/l [255, 869] vs. 678 IU/l [276, 1870]; p<0.05). This difference retained statistical significance after adjustment for differences between groups.

CONCLUSION

Statin therapy at the time of myocardial infarction is associated with lower peak creatine kinase concentrations. This suggests that statins may exhibit protective effects in the setting of myocardial ischemia and/or infarction in humans.

How do HMG-CoA reductase inhibitors prevent stroke?

Stroke is a heterogeneous disorder with significantly high morbidity and mortality. The relationship between serum cholesterol level and the incidence of stroke remains controversial. Recent evidence from primary and secondary prevention trials suggests that treatment with hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitors may reduce the incidence of stroke in patients with coronary artery disease (CAD). In this review, we attempt to outline and describe the potential mechanisms of HMG-CoA reductase inhibitors in the prevention of stroke. In addition to their lipid-lowering action HMG-CoA reductase inhibitors appear to exert their beneficial effects by various nonlipid-lowering mechanisms including anti-inflammatory effects, effect on endothelial function and coagulation cascade. Treatment with HMG-CoA reductase inhibitors is associated with decreased progression, plaque stablization and even regression of atheromatous plaque in the carotid arteries. HMG-CoA reductase inhibitors also inhibit the coagulation cascade at various levels such as activation of prothrombin, factor V, factor X and liberation of tissue factor in response to vascular injury. Inhibition of fibrinolysis occurs secondary to inhibition of plasmin generation. Pravastatin therapy is associated with a reduction in the size of aortic atheroma which is an independent risk factor for stroke. Lastly, left ventricular dysfunction after acute myocardial infarction is associated with an increased risk of stroke and HMG-CoA reductase inhibitors may indirectly decrease the incidence of stroke by reducing coronary events. Most of these effects are independent of the cholesterol-lowering effects of HMG-CoA reductase inhibitors. In conclusion, HMG-CoA reductase inhibitors may have a role in primary prevention of stroke in patients with CAD.

[Statins and cerebral ischemia]

<zakljucak> CVB su vodeci uzrok invalidnosti u svetu, drugi uzrok mortaliteta u nerazvijenim zemljama (na trecem mestu u razvijenim zemljama), a jedna trecina bolesnika umire unutar prvih 6 meseci od razbolevanja (95, 96). Ovo su zvanicni podaci Svetske zdravstvene organizacije, a statistika je otisla korak dalje i pokazala da u SAD svake 53. sekunde jedan covek oboli od CVB (97). Mozda bi pricu o statinima i IBM trebalo zavrsiti ovim izrazito nepovoljnim epidemioloskim podacima vezanim za CVB, koji naglasavaju znacaj iznalazenja adekvatne terapije koja bi smanjila rizik obolevanja (98), kao i ogromne troskove vezane za lecenje i posledicnu invalidnost. Aspirin dovodi do redukcije vaskularnog mortaliteta i morbiditeta vezanog za CVB od 13% klopidogrel do 22% (99), a statini nezavisno od upotrebe drugih lekova ukljucujuci i aspirin, do 30%. Imajuci u vidu sve ove izrazito dobre rezultate lecenja statinima, uz dozu rezervisanosti vezanu za eventualne udaljene efekte ove terapije, nema sumnje da se radi o lekovima koji ce uticati na promenu celokupnog pristupa lecenju bolesnika sa rizikom od IBM.

Lack of therapeutic interchangeability of HMG-CoA reductase inhibitors

OBJECTIVE

To review relevant literature and provide an opinion on the class effect of hydroxymethylglutaryl coenzyme A reductase inhibitors (statins).

DATA SOURCES

Primary and review articles were identified by MEDLINE search (1990-July 2002).

STUDY SELECTION AND DATA EXTRACTION

Editorials, studies, and review articles related to the class effect or therapeutic interchangeability of statins were reviewed. Also included was information that is relevant to this topic.

DATA SYNTHESIS

Although statins share common main actions, they may have clinically important differences in terms of efficacy and safety. At fixed or allowable dosages, rosuvastatin, atorvastatin, and simvastatin produced greater low-density lipoprotein cholesterol-lowering effects compared with other statins. Some statins have shown reduction in either cardiovascular and/or total mortality. Statins also differ in their structure, pharmacokinetics, potency, and rate of metabolism, any or all of which may have clinical significance. Although inconclusive, subtle differences in nonlipid effects of some statins may have contributed to positive benefits observed in clinical studies. As a result of drug-related deaths, cerivastatin was withdrawn voluntarily from the market, which may raise the question whether there is therapeutic interchangeability (due to class effect) among statins.

CONCLUSIONS

Despite the competition for market share and strategies attempting to identify differences in therapeutic value, few head-to-head comparisons between statins have been performed. The limited, available data suggest that statins are not therapeutically interchangeable.

Statin lipid-lowering therapy for acute myocardial infarction and unstable angina: efficacy and mechanism of benefit

The use of statin agents in patients with acute coronary syndromes (ACSs) remains an area of intense clinical interest. Statin therapy has an established secondary preventive benefit in patients with coronary artery disease, and its extension to ACS seems logical. A number of observational studies have shown an association between initiation of statin therapy early in ACS and improved clinical outcome. Additionally, 4 randomized controlled trials have examined the use of statin therapy for ACS: the Myocardial Ischemia Reduction with Aggressive Cholesterol Lowering (MIRACL) study, the Pravastatin Turkish Trial, the Fluvastatin on Risk Diminishing After Acute Myocardial Infarction (FLORIDA) study, and the Lipid-Coronary Artery Disease (L-CAD) study. Three of these trials showed a benefit with early initiation of statin therapy, whereas 1 trial demonstrated neither benefit nor harm. All the available trials lacked the power and design to sufficiently evaluate whether early initiation of statin therapy reduces mortality and reinfarction in patients with ACS. Four ongoing trials have been designed and sufficiently powered to determine whether statin therapy reduces the risk of death and reinfarction when initiated early in ACS treatment. A body of evidence suggests that the pleiotropic actions of statin agents might modulate benefit in ACS. This article summarizes the available data and provides a rationale for early initiation of statin therapy for patients with ACS.

HMG CoA reductase inhibitors affect the fibrinolytic system of human vascular cells in vitro: a comparative study using different statins

1. The results of several clinical studies investigating the effect of statin therapy on the fibrinolytic system in vivo are inconclusive. We compared the effect of six different statins (atorvastatin, cerivastatin, fluvastatin, lovastatin, pravastatin, simvastatin) on components of the fibrinolytic system expressed by human vascular endothelial cells and smooth muscle cells and by the human hepatoma cell line HepG2. 2. All statins used except pravastatin significantly decreased PAI-1 production in human endothelial and smooth muscle cells. This effect was also seen in the presence of IL-1 alpha and TNF-alpha. All statins except pravastatin increased t-PA production in human smooth muscle cells. On a molar basis cerivastatin was the most effective HMG CoA reductase inhibitor used. Only simvastatin and lovastatin increased t-PA production in endothelial cells. The effects on the fibrinolytic system were reversed by mevalonate. Statins decreased mRNA levels for PAI-1 in endothelial and smooth muscle cells and increased mRNA levels for t-PA in smooth muscle cells. Statins did not affect PAI-1 expression in HepG2 cells. Cell viability was not influenced by statins in endothelial cells and HepG2 cells whereas in smooth muscle cells a cytotoxic effect was seen at high concentrations. 3. If the effects on the fibrinolytic system of vascular cells in vitro shown in this study are also operative in vivo one could speculate that by increasing t-PA and decreasing PAI-1 at sites of vascular lesions statins might reduce fibrin formation and thrombus development. Such an effect might contribute to the clinically proven benefits of statin therapy.

Effect of concomitant or very early statin administration on in-hospital mortality and reinfarction in patients with acute myocardial infarction

In a retrospective analysis, 66 patients identified as having received a statin drug within 24 hours of admission for acute myocardial infarction were matched 3:1 with a control group of 198 patients not treated with a statin agent. End points of in-hospital mortality and in-hospital reinfarction were significantly lower in the statin-treated group, pointing to a benefit from very early statin treatment in acute myocardial infarction.

Elderly patients at risk for coronary heart disease or stroke: selecting an ideal product for lipid lowering

Coronary heart disease is an affliction of the elderly: 84% of those who die from the disease are over 65 years of age. In patients over 55 years, the incidence of stroke more than doubles with each decade of life. The 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors, or statins, have been shown to lower cholesterol and lipids in both middle-aged and elderly patients in large clinical trials. Some statins have been shown to improve endothelial function and vasodilation and to normalize thrombin formation, which may be among the mechanisms involved in both coronary event and stroke prevention.

Do HMG-CoA reductase inhibitors affect fibrinogen?

OBJECTIVE

To review commonly used fibrinogen assay methods and the evidence demonstrating an association between fibrinogen and increased risk of coronary artery disease and to review the current literature to determine and assess the impact of hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitors on fibrinogen.

DATA SOURCES

Primary and review articles identified from a MEDLINE search (1966-December 1999); references obtained from these publications were subsequently reviewed for additional relevant articles.

STUDY SELECTION AND DATA EXTRACTION

All articles were evaluated, and all relevant information was included in this review.

DATA SYNTHESIS

The Clauss method is currently the preferred method for determining plasma fibrinogen concentrations, due to its high degree of accuracy and precision. Furthermore, unlike immunologic methods, its reliability is unaffected by change in triglycerides. The effects of four HMG-CoA reductase inhibitors (atorvastatin, lovastatin, simvastatin, pravastatin) on fibrinogen have been evaluated. Atorvastatin has been shown to induce significant increases in fibrinogen (22% increase; p <0.05) by using the immunonephelometric method. This method also demonstrated that lovastatin use was associated with a 24.4% increase (p < 0.0001) in plasma fibrinogen concentration. Simvastatin has been shown in multiple studies using the Clauss method to have a neutral effect on fibrinogen. The majority of studies have revealed significant decreases (7-19%) in fibrinogen following treatment with pravastatin.

CONCLUSIONS

Future studies need to be performed evaluating the effects of HMG-CoA reductase inhibitors on fibrinogen, but using direct comparisons and clotting assay methodology.

Mechanisms of acute coronary syndromes and the potential role of statins

The conventional concepts of the pathogenesis of acute coronary syndromes are changing. High-risk lesions are not necessarily the angiographicaly 'tight' stenoses. Rather, vulnerable lesions are those that are unstable, with a large lipid core and a thin fibrous cap. Plaque instability is closely related to the development of inflammation within the intima and acute coronary syndromes result from rupture of a vulnerable atherosclerotic plaque. Stabilization of lesions by modification of structure and content, rather than simple improvement in the luminal diameter, provides a new therapeutic target. Stabilization may be accomplished through lifestyle changes and appropriate pharmacologic therapy. In the past few years, it has become evident that a major beneficial effect of statins is to induce plaque stability and regression. In fact, statins, in addition to lowering low-density lipoprotein cholesterol, have a variety of pleiotropic, or cholesterol-independent, effects that make them a particularly suitable choice in patients with acute coronary syndromes. Among these are improvements in endothelial function, smooth muscle cells, thrombus formation/platelet function, and inflammation.

Pluripotential mechanisms of cardioprotection with HMG-CoA reductase inhibitor therapy

Treatment with hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitors has been accompanied by a reduced risk of cardiovascular events. Rapid onset of clinical benefit and weak correlations between plasma low density lipoprotein-cholesterol levels and coronary lumen change or cardiovascular events indicates that nonlipid mechanisms are involved in this beneficial effects with HMG-CoA reductase inhibitors. Furthermore, more rapid onset of clinical benefit with HMG-CoA reductase inhibitors in patients with acute coronary syndromes or acute myocardial infarction than in those with stable coronary heart disease suggest that HMG-CoA reductase inhibitors facilitate repair of ruptured or ulcerated atherosclerotic plaque, facilitate plaque stabilization and/or reduce thrombus formation on ruptured plaques. Treatment with HMG-CoA reductase inhibitors improved endothelial dysfunction in patients with hypercholesterolemia and this improvement in endothelial function was not correlated with reduction in total serum cholesterol levels. Similarly, reduction in endothelial pre-proendothelin mRNA expression and endothelin synthesis and blood pressure lowering with HMG-CoA reductase inhibitors occurred independent of lipid-lowering. Finally, HMG-CoA reductase inhibitors increased endothelial nitric oxide levels i.e. upregulated endothelial nitric oxide synthetase expression via post-transcriptional mechanisms and prevented its down-regulation by oxidized LDL-C. HMG-CoA reductase inhibitors have been shown to modulate the immune response by inhibiting activation of immune-competent cells such as macrophages, and antigen presentation to macrophages by T cells. Treatment with HMG-CoA reductase inhibitors can reduce expression, production and circulating levels of chemokines (monocyte chemoattractant protein-1) and proinflammatory cytokines [tumor necrosis factoralpha, interleukin (IL)-6 and IL-1beta]. HMG-CoA reductase inhibitors reduced inflammation in human atheroma: significantly fewer macrophages and T cells, less oxidized LDL-C and higher collagen content. In addition, treatment with HMG-CoA reductase inhibitor led to decreased cell death within the atheroma. Treatment with these agents also reduced expression of inducible cellular adhesion molecules, decreased secretion of metalloproteinases by macrophages, reduced vascular smooth muscle cell apoptosis. Lastly, HMG-CoA reductase inhibitors appear to have important effects on the thrombogenesis: reduced expression of tissue factor production and activity; increased production of tissue factor package inhibitor; decreased platelet thrombus formation and improved fibrinolysis as a result of lowered plasminogen activator inhibitor-1 levels. As the pluripotential cardioprotective mechanisms of HMG-CoA reductase inhibitors are further elucidated, it is envisaged that treatment with HMG-CoA reductase inhibitors will be initiated earlier and more frequently in patients with hypercholesterolemia.

[Effect on plasma fibrinogen of hypercholesterolaemia treatment with pravastatin]

OBJECTIVE

To determine whether hypercholesterolaemia treatment with pravastatin causes modifications in plasma fibrinogen.

DESIGN

Descriptive, prospective pharmacological intervention study, with two transversal cuts, one at the start and one after 6 months pravastatin treatment.

SETTING

Health area located in the suburbs of Valencia.

PATIENTS

Hypercholesterolaemia cases diagnosed de novo and treated with pravastatin for 6 months. Sample size was calculated for paired data with an alpha error of 0.05 and a beta error of 20%. The fibrinogen difference thought relevant was set at 40 mg/dl. Variability was deduced from a mini-sample of 15 cases, obtaining a total of 57 patients. Sex, age, height, weight, BMI, count, formula, globular sedimentation rate (GSR), glucaemia, total, HDL and LDL cholesterol, and triglycerides were recorded.

MEASUREMENTS AND MAIN RESULTS

Mean age was 55.9, height 161.9 cm and initial weight 73.9 kg (mean BMI 28.1 kg/m(2)). After six months pravastatin treatment (10/20 mg/day) we found no significant differences in glucaemia, GSR or leukocytes. There were differences in weight, that fell by 1.5 kg (0.6 kg/m(2)), systolic pressure (4.3 mmHg) and diastolic pressure (2.7 mmHg) on average. We found the following differences for lipids: 42.3 mg/dl (15.2%) drop in mean total cholesterol, 27 mg/dl (14.5%) in LDL cholesterol, and 36.2 mg/dl (21.9%) in triglycerides. We found a mean increase in HDL cholesterol of 4.4 mg/dl. There was a mean drop of 43.7 mg/dl (11.9%) in fibrinogen.

CONCLUSIONS

We found an 11.9% drop of plasma fibrinogen in patients with hypercholesterolaemia treated with pravastatin.

Biological basis for statin therapy in stroke prevention

Hypercholesterolemia has not been considered an important risk factor for stroke; however, statin therapy reduces stroke in coronary heart disease patients. Statins may provide cerebrovascular protection through various mechanisms that include a reduction in the incidence of embolic stroke from cardiac, aortic and carotid sites, stabilization of vulnerable carotid atherosclerotic plaque, and improvement in cerebral blood flow.

Mechanisms modifying atherosclerotic disease - from lipids to vascular biology

Recent clinical trials of three statins, pravastain, simvastatin and lovastatin, have demonstrated a major reduction in acute coronary events typically precipitated by plaque rupture. However, angiographic studies with several statins have shown that they do not appear to greatly affect the size of pre-existing plaques. These findings strongly suggest that the demonstrated protective effect of these statins is mediated through changes in plaque composition rather than size, highlighting the greater importance of composition than size in determining clinical outcome. Atherosclerotic plaques are composed of a thrombogenic lipid-rich core protected by a fibrous cap comprising smooth muscle cells (SMCs) and inflammatory cells, predominantly macrophages. SMCs are the only cell type in the atherosclerotic plaque capable of synthesizing a strong fibrous cap. Their survival is therefore crucial to plaque stability. In contrast, inflammatory cells such as macrophages increase the risk of plaque rupture by a number of mechanisms. Thus, in atherosclerosis, there is a balance between the influence of inflammatory cells tending towards plaque instability and the reparative influence of SMCs tending to plaque stability. The implication of the successful outcome studies is that the statins tested may beneficially influence this balance either by decreasing inflammation or promoting repair or both. However, because statins do not have a uniform effect on all the biological processes contributing to plaque rupture and subsequent thrombosis, the potential benefit from treating with a statin cannot necessarily be presumed or predicted from its lipid lowering potency alone. Therefore prescription of statins to prevent cardiovascular events should be based on the evidence of outcome trials.

Statins and the kidney

Experience to date suggests that 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors or statins can be used relatively safely and effectively to treat dyslipidaemia complicating renal disease. Recent studies suggest that in addition to lowering plasma lipid levels, these drugs modify other factors that contribute to vascular injury. Furthermore, statins could slow the progression of chronic renal failure and may augment the action of immunosuppressive therapy after renal transplantation. Such newly defined actions, some of which could be unrelated to lipid lowering, are likely to extend the applications of statins in nephrology.

Effects of pravastatin sodium and simvastatin on plasma fibrinogen level and blood rheology in type II hyperlipoproteinemia

Elevated plasma fibrinogen level is known to progress atherosclerosis and to be one of the risk factors for the occurrence of cardiovascular diseases. The objective of this study is to evaluate the changes in plasma fibrinogen level and blood rheology in patients with type II hyperlipoproteinemia before and after random administrations of HMG-CoA (3-hydroxy-e-methylglutaryl-cocarboxylase-A) reductase inhibitors, pravastatin sodium and simvastatin, and compare with results in normal subjects. Of a total of 28 patients with type II primary hyperlipoproteinemia with > 230 mg/dl fasting total plasma cholesterol, 16 patients (mean, 59.7 years old) were administered 10-15 mg/day of pravastatin sodium for an average of 10.2 weeks, and 12 patients (mean, 62.0 years old) were administered 5-10 mg/day of simvastatin for an average of 13.9 weeks. Patients were evaluated before and after drug administration and results were compared with those of 16 normal subjects of similar age (mean, 56.9 years old). Blood viscosities were measured using a cone-plate viscometer (Biorheolizer, BRL-1000, Japan). The following were measured before and after drug administration: whole blood viscosity at shear rates of 75-375 s-1, corrected blood viscosity at low (112.5 s-1) and high (225.0 s-1) shear rates for the standard hematocrit of 45%, plasma viscosity, hematocrit, total protein, serum albumin, and plasma fibrinogen. Total cholesterol level was significantly decreased (from 270 to 225, mg/dl, mean values; P < 0.0007) an average of 10.2 weeks after start of pravastatin sodium administration. In addition to the reductions of whole blood viscosity, at every shear rate examined, corrected blood viscosity, and plasma viscosity, plasma fibrinogen levels were significantly decreased (from 354 to 309 mg/dl, mean values; P < 0.0007) after start of pravastatin sodium administration. Fibrinogen level and blood rheology were not significantly changed after start of simvastatin administration despite similar significant reductions in total cholesterol level (from 260 to 207 mg/dl, mean values; P < 0.0001) to those in the case of pravastatin sodium. From the results, we conclude that administration of pravastatin sodium, but not simvastatin, reduced the plasma fibrinogen level and blood viscosities to normal levels in type II hyperlipoproteinemic patients while both drugs reduced total cholesterol level. The hydrophilicity and a small binding capacity with plasma protein of pravastatin sodium may be responsible in part for the beneficial hemorheologic effects observed in the patients with type II hyperlipoproteinemia. Further investigations should be conducted to confirm the findings observed.