The use of statins in acute coronary syndromes: the mechanisms behind the outcomes

Evaluation of Ischemia with No Obstructive Coronary Arteries (INOCA) and Contemporary Applications of Cardiac Magnetic Resonance (CMR)

Ischemia with no obstructive coronary arteries (INOCA) is a relatively newly discovered ischemic phenotype that affects patients similarly to obstructive coronary artery disease (CAD) but has a unique pathophysiology and epidemiology. Patients with INOCA present with ischemic signs and symptoms but no obstructive CAD seen on coronary CTA or invasive coronary angiography, which can assess epicardial vessels. The mechanisms of INOCA can be grouped into three endotypes: coronary microvascular dysfunction, epicardial coronary vasospasm, or a combination of both. Accurate and comprehensive assessment of both epicardial and microvascular disease in suspected cases of INOCA is crucial for providing targeted therapy and improving outcomes in this underrepresented population. This review aims to clarify the complex pathophysiology of INOCA, present an overview of invasive and non-invasive diagnostic methods, and examine contemporary approaches for coronary perfusion assessment using cardiac magnetic resonance (CMR). We also explore how recent advancements in quantitative CMR can potentially revolutionize the evaluation of suspected INOCA by offering a rapid, accurate, and non-invasive diagnostic approach, thereby reducing the alarming number of cases that go undetected.

Do Statins Have a Positive Impact on Patients with Coronary Microvascular Dysfunction on Long-Term Clinical Outcome? A Large Retrospective Cohort Study

Objectives

To investigate the influence of statins on major adverse cardiovascular events (MACE) in patients with coronary microvascular dysfunction (CMVD).

Participants

23,494 patients who received coronary angiography (CAG) were included. Thrombolysis in Myocardial Infarction, Myocardial Perfusion Grading (TMPG), a useful angiographic method, was used to evaluate CMVD.

Results

Using multivariate analysis, NYHA III/IV (HR, 1.44; 95% CI, 1.03-2.01; P=0.031), PCI history (HR, 3.69; 95% CI, 2.57-5.31; P<0.001), TG (HR, 1.15; 95% CI, 1.06-1.26; P=0.001), creatinine (HR, 1.00; 95% CI, 1.00-1.01; P<0.001), cTnT (HR, 0.98; 95% CI, 0.96-0.99; P<0.001), heart rate (HR, 0.98; 95% CI, 0.97-0.99; P=0.001), β-blocker (HR, 0.68; 95% CI, 0.51-0.91; P=0.008), aspirin (HR, 0.38; 95% CI, 0.24-0.61; P<0.001), and statins (HR, 0.33; 95% CI, 0.19-0.60; P<0.001) significantly correlated with reduced MACE in CMVD patients. In subgroups analysis, statins decreased MACE overall (HR, 0.33; 95% CI, 0.19-0.59; P<0.001) and in CMVD patients with smoking history (HR, 0.64; 95% CI, 0.43-0.93; P=0.014), diabetes (HR,0.27; 95% CI,0.12-0.61; P=0.002), hypertension (HR, 0.10; 95% CI, 0.03-0.36; P=0.001), and hypertension and diabetes (HR, 0.09; 95% CI, 0.014-0.53; P=0.008).

Conclusion

Statins could reduce MACE in patients with CMVD.

Different Effect of Statins on Platelet Oxidized-LDLReceptor (CD36 and LOX-1) Expressionin Hypercholesterolemic Subjects

Hydroxymethyl-glutaryl-CoA-reductase inhibitors (statins) reduce cardiovascular mortality by decreasing cholesterol as well as by non-lipid-related actions. Oxidized low-density lipoproteins (ox-LDL) are pro-atherogenic molecules and potent platelet agonists. CD36 and lectin-like ox-LDL receptor-1 (LOX-1) are specific ox-LDL receptors also expressed in platelets. This study was planned to address whether treatment with atorvastatin 10 mg/day, pravastatin 40 mg/day or simvastatin 20 mg/day could affect platelet CD36 and LOX-1 expression. Twenty-four patients for each treatment were evaluated after 3, 6, and 9 days and at 6 weeks for complete lipid profile (chromogenic), ox-LDL (ELISA), platelet P-selectin (P-sel), CD36, LOX-1 (FACS), and intracellular citrullin recovery (iCit) (HPLC). Data show hyperactivated platelets (P-sel absolute values, percent variation in activated cells, all p < 0.001), and CD36 and LOX-1 overexpression (all p < 0.001) in patients at baseline. P-sel, CD36, and LOX-1 were significantly decreased by atorvastatin and simvastatin (all p < 0.01) and related with iCit increase (r = 0.58,p < 0.001) and platelet-associated ox-LDL (r = 0.51, p < 0.01) at 9 days. Pravastatin reduced LOX-1 and P-sel (p < 0.05) at 6 weeks in relation with decreased LDL and ox-LDL (r = 0.39, p < 0.01 and r = 0.37, p < 0.01, respectively). These data suggest that atorvastatin and simvastatin reduce platelet activity by exposure of CD36 and LOX-1 before significant LDL reduction, whereas pravastatin action is detected later and in relation with LDL and ox-LDL lowering. Rapid and consistent reduction of CD36 and LOX-1 could be considered a direct anti-atherothrombotic mechanism related to the role of ox-LDL in platelet activation, platelet-endothelium interactions, and NO synthase activity.

Different time course for prevention of coronary and stroke events by atorvastatin in the Anglo-Scandinavian Cardiac Outcomes Trial-Lipid-Lowering Arm (ASCOT-LLA)

The lipid-lowering properties of statins reduce rates of coronary artery disease (CAD) events and strokes. Findings of recently conducted, longitudinal intervention studies suggest that these benefits occur early and may be, in part, independent of the lipid-lowering properties of statin therapy. We analyzed data from the Anglo-Scandinavian Cardiac Outcomes Trial-Lipid-Lowering Arm (ASCOT-LLA) to determine the timing of cardiovascular risk reduction. Relative risk reductions in CAD events were large compared with placebo, becoming apparent at 30 days and significant within 3 months, but they tended to decrease with time. Risk reductions in stroke were also apparent at 30 days but remained constant throughout the trial. Significant differences in hazard ratio between atorvastatin and placebo occurred at 2-year follow-up. Such apparently differential effects on CAD and stroke events suggest that mechanisms of action for CAD and stroke prevention may be different. These observations support the hypothesis that non-lipid-lowering actions of atorvastatin may have contributed to early protection against CAD in ASCOT-LLA.

High-density lipoprotein, but not low-density lipoprotein cholesterol levels influence short-term prognosis after acute coronary syndrome: results from the MIRACL trial

AIMS

Patients with acute coronary syndrome (ACS) in the Myocardial Ischaemia Reduction with Aggressive Cholesterol Lowering (MIRACL) study had diminished cardiovascular events after 16 weeks of treatment of atorvastatin 80 mg daily. We determined whether plasma lipoproteins at baseline and then at 6 weeks after randomization predicted clinical outcome.

METHODS AND RESULTS

Cox proportional hazards models were constructed to determine relations between lipoproteins and clinical endpoint events. Baseline LDL cholesterol (LDL-C) did not predict outcome. In contrast, baseline HDL-C predicted outcome with a hazard ratio of 0.986 per mg/dL increment in HDL-C, P<0.001, indicating 1.4% reduction in risk for each 1 mg/dL increase in HDL-C. Atorvastatin treatment profoundly lowered LDL-C, but had minimal effect on HDL-C. Neither Week 6 LDL-C nor absolute change of LDL-C from baseline by Week 6 had any significant impact on clinical endpoints occurring between Week 6 and Week 16 after randomization.

CONCLUSION

Plasma HDL-C, but not LDL-C, measured in the initial stage of ACS predicts the risk of recurrent cardiovascular events over the ensuing 16 weeks. LDL-C reduction does not account for the clinical risk reduction with atorvastatin treatment after ACS. This finding may suggest that the clinical benefit of atorvastatin after ACS is mediated by qualitative changes in the LDL particle and/or by non-lipid (pleiotropic) effects of the drug.

Statins as Immunomodulatory Agents

Statins have long been thought to exert their benefits by reducing cholesterol synthesis. However, the fact that mevalonate is the precursor of isoprenoids that regulate diverse cellular functions has led investigators to examine pleiotropic effects for these agents. Major histocompatibility complex class II (MHC-II) molecules, which affect the immune response and organ rejection after transplantation, may be induced by the proinflammatory cytokine interferon gamma (IFN-γ). An experiment was conducted to determine whether statins affect the regulation of MHC-II expression by IFN-γ in cultured human endothelial cells and monocyte/macrophages. Statins were found to repress the induction of MHC-II by IFN-γ. This may explain the immunosuppressive effects of statins seen in two clinical trials of organ transplantation and suggest a potential role for statins as immunosuppressive agents.

Chemokines and atherosclerosis

Atherosclerosis is an inflammatory disease of the vessel wall, characterized by the accumulation of leukocytes, especially macrophages and T-cells. Chemokines are small heparin-binding polypeptides, whose main function is to attract cells to the areas of developing inflammation. They function by ligating G-protein coupled chemokine receptors initiating different signaling cascades. In vivo and in vitro investigations showed that chemokines are produced by a variety of cells and play important roles in the development and progression of many physiological and pathological conditions including atherosclerosis. Chemokines such as MCP-1, MCP-4, MIP-1 and RANTES may mediate leukocyte trafficking to, and their retention in, the plaque while CXCL16 seems to fulfill the dual function of a chemokine and a scavenger receptor. Chemokine and chemokine receptor homologues are secreted by several viruses, which may also play a role in the pathogenesis of atherosclerosis. Expression levels and gene polymorphisms of some chemokines may become useful clinical markers of atherosclerosis and other cardiovascular diseases. Modulation of chemokines and chemokine receptors' expression as well as their signaling pathways may provide important anti-atherogenic strategies.

Decrease of hemostatic cardiovascular risk factors by aggressive vs. conventional atorvastatin treatment in patients with Type 2 diabetes mellitus

BACKGROUND

Patients with Type 2 diabetes mellitus have increased levels of hemostatic risk variables for cardiovascular disease, such as fibrinogen, von Willebrand factor (VWF), factor (F)VIIa, d-dimer and plasminogen activator inhibitor-1 (PAI-1).

OBJECTIVES

To evaluate the effect of aggressive vs. standard dose atorvastatin on hemostatic cardiovascular risk factors in patients with Type 2 diabetes mellitus.

PATIENTS AND METHODS

The effect of 30 weeks of treatment with atorvastatin 10 and 80 mg on hemostatic cardiovascular risk factors was assessed in a randomized double-blind placebo-controlled trial on 217 patients with Type 2 diabetes mellitus and dyslipidemia.

RESULTS AND CONCLUSIONS

Atorvastatin 10 and 80 mg dose-dependently reduced d-dimer (7.4% and 8.5%, respectively, P for trend = 0.004) and PAI-1 antigen levels (9.0% and 18%, respectively, P for trend = 0.021). Levels of fibrinogen, VWF, tissue-type plasminogen activator and FVIIa were not influenced by atorvastatin. In conclusion, in patients with Type 2 diabetes mellitus, atorvastatin dose-dependently improved the levels of the hemostatic risk variables d-dimer and PAI-1.

Time-dependent effect of statins on platelet function in hypercholesterolaemia

BACKGROUND

Reduction of platelet activity induced by statins has been described as a positive effect exerted by such molecules on vascular thrombotic events. However, the relations among cholesterol (LDL-C) reduction, the timing of the antiplatelet effect, the involved mechanisms and the doses of each statin able to reduce platelet function are not actually well known. The aim of our study was to evaluate the impact of simvastatin (20 mg day-1), atorvastatin (10 mg day-1), fluvastatin (40 mg day-1) and pravastatin (40 mg day-1) on platelet function in hypercholesterolaemic subjects with relation to (LDL-C), oxidized-LDL (ox-LDL) and antiport mechanism modifications.

MATERIALS AND METHODS

Sixteen subjects were assigned to each treatment (40 males, 24 females, mean age 48.7 +/- 13.4, LDL-C 5.13 +/- 0,23 mmol L-1) and evaluated for platelet surface P-selectin (P-sel), lipid profile, ox-LDL, platelet-associated ox-LDL (Pox-LDL), platelet cholesterol content, antiport mechanisms, and intracellular and systemic NO synthase every 7 days for one month.

RESULTS

Our data show a strong relation between enhanced P-sel and Pox-LDL (r = 0.68, P < 0.01). Simvastatin, atorvastatin, fluvastatin and pravastatin reduce platelet activity after 1, 2, 3 and 4 weeks of treatment, respectively (P < 0.001, P < 0.001, P < 0.01, P < 0.05). Pox-LDL are modulated early by simvastatin, atorvastatin and fluvastatin Pox-LDL (r = 0.66, 0.65 and 0.52; P < 0.001, 0.001 and 0.01, respectively) whereas LDL-C and ox-LDL reductions associated to modifications of antiport activity act later. Moreover, they are the most relevant finding in pravastatin-related subjects.

CONCLUSIONS

Our data suggest a different impact of several statins on platelet function, which is initially related to interference with Pox-LDL rather than LDL-C reduction.

The effect of Mediterranean diet on the risk of the development of acute coronary syndromes in hypercholesterolemic people: a case-control study (CARDIO2000)

BACKGROUND

Hypercholesterolemia has been identified as a major risk factor for the development of coronary artery disease. The aim of this study was to assess the effect of a Mediterranean diet on the development of non-fatal acute coronary syndromes (ACS) in hypercholesterolemic people, with or without statin treatment.

METHODS

During 2000-2001, 848 randomly selected patients with a first event of coronary heart disease and 1078 cardiovascular disease-free people, matched to the patients by sex, age and region, were studied. Treatment of hypercholesterolemia with statin and the adoption of a Mediterranean diet were recorded.

RESULTS

Hypercholesterolemia was present in 534 (63%) out of 848 coronary patients and 399 (37%) out of 1078 control participants. One hundred and seventy-one (32%) of the hypercholesterolemic patients and 168 (42%) of the hypercholesterolemic control participants were treated with statins and also followed a Mediterranean diet. The analysis showed that the combination of a Mediterranean diet and statin medical therapy is associated with an additional reduction of the coronary risk (odds ratio = 0.57, P < 0.01), independently from cholesterol levels and the other cardiovascular factors.

CONCLUSION

The adoption of a Mediterranean diet by hypercholesterolemic people seems to reinforce the benefits from statin treatment on lipid levels and reduces the risk of developing ACS. However, it is hard to claim that our findings suggest causal evidence, and in order to explain the potential common mechanism between diet and statin treatment much remains to be learned.

Effect of statin (HMG-Co-A-Reductase Inhibitor) use on 1-year mortality and hospitalization rates in older patients with cardiovascular disease living in nursing homes

OBJECTIVES

To quantify the effect of statins on 1-year mortality, hospitalizations, and decline in physical function among patients with cardiovascular disease (CVD) aged 65 and older living in nursing homes.

DESIGN

Retrospective cohort study.

SETTING

All Medicare/Medicaid certified nursing homes (N = 1,492) in Maine, New York, Mississippi, and South Dakota.

PARTICIPANTS

We identified 51,559 older patients with CVD from a population database that merged sociodemographic data and functional, clinical, and drug treatments from more than 300,000 newly admitted nursing home residents from 1992 to 1997. Statin users (n = 1,313) were matched with nonusers (n = 1,313) in the same facilities.

MEASUREMENTS

All-cause mortality, hospitalization, combined endpoint of mortality or hospitalization, and decline in physical function were determined at 1 year, and survival analysis was performed.

RESULTS

Prevalence of statin use in this frail older cohort with CVD was 2.6%. Statin use varied by age, gender, comorbid condition, medication use, and cognitive and physical function. One-year mortality was 229/1,000 person-years in the statin group and 404/1,000 person-years in the nonusers, with an adjusted hazard rate ratio (HRR) of 0.69, 95% confidence interval (CI) = 0.58-0.81. The estimated number needed to treat was seven (95% CI = 5-13). This association with improved all-cause mortality was evident for women and men and for age groups 75 to 84, and 85 and older.

CONCLUSION

Statin therapy is associated with improved clinical outcomes, including reduction in 1-year all-cause mortality, and the combined endpoint of death or hospitalization in a frail older population with CVD. Some caution should be taken in interpreting these results because potential bias from residual confounding could affect these results.

Statins as immunomodulators

HMG-CoA reductase inhibitors, or statins, are effective lipid lowering agents, extensively used in medical practice. Statins have never been shown to be involved in the immune response, although few clinical reports have suggested a better outcome of cardiac transplantation in patients under pravastatin therapy. Major histocompatibility complex class II (MHC-II) molecules are directly involved in the activation of T lymphocytes and in the control of the immune response. Whereas only a limited number of specialized cell types express MHC-II constitutively, numerous other cells become MHC-II positive upon induction by interferon gamma (IFN-gamma). We and others recently demonstrated that statins act as direct inhibitors of induction of MHC-II expression by IFN-gamma and thus as repressors of MHC-II-mediated T cell activation. This effect was observed in several cell types, including primary human endothelial cells and macrophages. Interestingly, this inhibition is specific for inducible MHC-II expression and does not concern either constitutive expression of MHC-II or expression of MHC-I. In repressing induction of MHC-II, and subsequent T lymphocyte activation, statins therefore behave as a novel type of immunomodulator. This unexpected effect provides a scientific rationale for suggesting the use of statins as novel immunosuppressors, not only in organ transplantation but in numerous other pathologies as well.