Statin intake is associated with decreased insulin sensitivity during cardiac surgery

Perioperative glycemic control in patients undergoing cardiac surgery

Diabetes mellitus (DM) is one of the most common chronic diseases, affecting globally about 537 million adults. Cardiovascular disease remains the leading cause of death and medical emergencies in the DM patient population. As a result, about 40% of patients with DM undergo cardiac surgery, mainly in the coronary arteries. Uncontrolled hyperglycemia, especially the prolonged condition, is an independent factor in postoperative mortality and the cause of many serious complications, such as surgical wound infection, sepsis, renal failure or cerebral or cardiovascular incidents. Adequate glycemic control in the perioperative period is the most important way to prevent the above complications. The issue has remained an important topic of many observational and experimental studies for years. This paper summarizes the current knowledge with regard to strategies of hyperglycemic control in patients undergoing cardiac surgery.

Effect of Long-Term Allopurinol Therapy on Left Ventricular Mass Index in Patients with Ischemic Heart Disease; A Cross-Sectional Study

Background

Left ventricular hypertrophy (LVH), as assessed by measurement of left ventricular mass (LVM), is one of the most important cardiovascular risk factors. It is commonly present in patients with ischemic heart disease (IHD), irrespective of the level of blood pressure; recently, oxidative stress has been shown to be an important factor in its development. The question then arises: can this risk factor be modified by antioxidant treatment (e.g., with allopurinol, a xanthine oxidase inhibitor)?

Methods

This is an observational study with a cross-sectional design which explored the association between long-term (>12 months) allopurinol therapy and LV mass index (LVMI) as well as geometry in patients generally receiving standard treatments for IHD. The primary endpoint was LVMI measurement (by 2D-echocardiography) and secondary endpoints included the association of allopurinol use with LV function (ejection fraction), blood pressure, glycemic control, and lipid profile.

Results

Ninety-six patients on standard anti-ischemic drug treatment (control group) and 96 patients who were additionally taking allopurinol (minimum dose 100 mg/day) were enrolled. Both groups were matched for age, sex, height, and co-morbidities, but poorer kidney function in the allopurinol group required further sub-group analysis based on renal function. Allopurinol treatment was associated with the lowest LVMI in the patients with normal serum creatinine (median LVMI; 70.5 g/m²): corresponding values were 76.0 and 87.0 in the control group with, respectively, normal and elevated serum creatinine, and 89.5 in the allopurinol group with elevated serum creatinine (P=0.027). In addition, allopurinol was associated with better glycemic control (HbA1c) with a difference of 0.8% (95% CI; 1.3, 0.2) (P=0.004) as compared with control patients.

Conclusion

In our population, treatment with allopurinol (presumably because of its anti-oxidant properties) has shown a tendency to be associated with smaller LVM in IHD patients with normal serum creatinine, along with better glycemic control.

Best Treatment Strategies With Statins to Maximize the Cardiometabolic Benefits

Statins are important for preventing adverse cardiovascular events in patients with both high and low risk of vascular disease, by reducing the levels of low-density lipoprotein cholesterol (LDL-C). However, statins dose-dependently increase adverse effects and increase the risk of type 2 diabetes. Previously, it was hypothesized this was caused by to off-target effects, but recent studies demonstrate it is caused by on-target effects. Nonetheless, the American guidelines recommend the use of high-intensity statin therapy, and extend its use to most people at risk of vascular diseases, particularly older people. In contrast, European, Korean, and Japanese committees have expressed concerns about the potential adverse effects of using high-intensity statins for lifelong periods in a large fraction of the population. Patients who have achieved LDL-C levels below currently recommended targets may still experience cardiovascular events, resulting from residual risk. Ezetimibe, PCSK9 inhibitors, inclisiran, and ANGPTL3 antisense oligonucleotides are promising alternative non-statin drugs. Of interest, cross-talk between hypercholesterolemia and the renin-angiotensin-system exists at multiple levels of insulin resistance and endothelial dysfunction. There are still unanswered questions on how to maximize the cardiometabolic benefits of statins in patients. We will discuss the results of randomized clinical trials, meta-analysis, and recent clinicopharmacogenetic studies, and propose practical guidelines to maximize the cardiometabolic benefits while reducing adverse effects and overcoming residual risk.

Pravastatin improves risk factors but not ischaemic tolerance in obese rats

Statins are effective in management of dyslipidaemia, and a cornerstone of CVD prevention strategies. However, the impacts of their pleiotropic effects on other cardiovascular risk factors and myocardial responses to infarction are not well characterised. We hypothesised that pravastatin treatment in obesity improves lipid profiles, insulin-resistance and myocardial resistance to ischaemia/reperfusion (I/R) injury. Wistar rats were fed a control (C) chow or high carbohydrate and fat diet (HCFD) for 16 weeks with vehicle or pravastatin (prava 7.5 mg/kg/day) treatment for 8 weeks. At 16 weeks HOMAs were performed, blood samples collected and hearts excised for Langendorff perfusions/biochemical analyses. Anti-oxidant activity and proteins regulating mitochondrial fission/fusion and apoptosis were assessed. The HCFD increased body weight (736±15 vs. 655±12 g for C; P<0.001), serum triglycerides (2.91±0.52 vs. 1.64±0.26 mmol/L for C; P<0.001) and insulin-resistance (HOMA- 6.9±0.8 vs. 4.2±0.5 for C; P<0.05) while prava prevented diet induced changes and paradoxically increased lipid peroxidation. The HCFD increased infarct size (34.1±3.1% vs. 18.8±3.0% of AAR for C; P<0.05), which was unchanged by prava in C and HCFD animals. The HCFD decreased cardiac TxR activity and mitochondrial MFN-1 and increased mitochondrial DRP-1 (reducing MFN-1:DRP-1 ratio) and Bax expression, with the latter changes prevented by prava. While unaltered by diet, cytosolic levels of Bax and caspase-3 were reduced by prava in C and HCFD hearts (without changes in cleaved caspase-3). We conclude that obesity, hyper-triglyceridemia and impaired glycemic control in HCFD rats are countered by prava. Despite improved risk factors, prava did not reduce myocardial infarct size, potentially reflecting its complex pleiotropic impacts on cardiac GPX activity and MFN-1, DRP-1, caspase-3 and Bcl-2 proteins.

Statins and Diabetes

A statin is first-line drug therapy for dyslipidemia. Clinical trial data suggest there is an increase in the incidence of new-onset type 2 diabetes mellitus with statin use. The National Lipid Association (NLA) Statin Diabetes Safety Task Force concluded that the cardiovascular benefit of statin therapy outweighs the risk for developing diabetes. The NLA panel advocated following the standards of care from the American Diabetes Association for screening and diagnosis of diabetes, and emphasized the importance of lifestyle modification. This article summarizes NLA's review of the evidence, expanding it to include recent results, and outlines the clinical recommendations.

Statins and diabetes

A statin is first-line drug therapy for dyslipidemia. Clinical trial data suggest there is an increase in the incidence of new-onset type 2 diabetes mellitus with statin use. The National Lipid Association (NLA) Statin Diabetes Safety Task Force concluded that the cardiovascular benefit of statin therapy outweighs the risk for developing diabetes. The NLA panel advocated following the standards of care from the American Diabetes Association for screening and diagnosis of diabetes, and emphasized the importance of lifestyle modification. This article summarizes NLA's review of the evidence, expanding it to include recent results, and outlines the clinical recommendations.

Is statin-induced diabetes clinically relevant? A comprehensive review of the literature

In those predisposed to the development of diabetes (the insulin resistant, obese and older patients) statins may increase the risk of developing diabetes. Despite the fact that the conversion to diabetes is generated from post hoc analyses, it seems to be a class effect with a dose-response relationship. However, statins have not been clearly shown to increase diabetic microvascular complications (retinopathy, nephropathy and neuropathy). Thus, the clinical significance of increased glucose levels in patients treated on statins is uncertain. While the exact mechanism for how statins increase the risk of diabetes is unknown, a possible explanation is through a reduction in adiponectin levels. Despite the fact that higher statin doses are more likely to lead to new-onset diabetes, for every case of diabetes caused, there are approximately three cardiovascular events reduced with high dose versus moderate dose statin therapy. Overall, the small risk of developing type 2 diabetes with statin therapy is far outweighed by the potential of statins to decrease cardiac events.

Statins impair glucose uptake in human cells

OBJECTIVE

Considering the increasing number of clinical observations indicating hyperglycemic effects of statins, this study was designed to measure the influence of statins on the uptake of glucose analogs by human cells derived from liver, adipose tissue, and skeletal muscle.

DESIGN

Flow cytometry and scintillation counting were used to measure the uptake of fluorescently labeled or tritiated glucose analogs by differentiated visceral preadipocytes, skeletal muscle cells, skeletal muscle myoblasts, and contact-inhibited human hepatocellular carcinoma cells. A bioinformatics approach was used to predict the structure of human glucose transporter 1 (GLUT1) and to identify the presence of putative cholesterol-binding (cholesterol recognition/interaction amino acid consensus (CRAC)) motifs within this transporter. Mutagenesis of CRAC motifs in SLC2A1 gene and limited proteolysis of membrane GLUT1 were used to determine the molecular effects of statins.

RESULTS

Statins significantly inhibit the uptake of glucose analogs in all cell types. Similar effects are induced by methyl-β-cyclodextrin, which removes membrane cholesterol. Statin effects can be rescued by addition of mevalonic acid, or supplementation with exogenous cholesterol. Limited proteolysis of GLUT1 and mutagenesis of CRAC motifs revealed that statins induce conformational changes in GLUTs.

CONCLUSIONS

Statins impair glucose uptake by cells involved in regulation of glucose homeostasis by inducing cholesterol-dependent conformational changes in GLUTs. This molecular mechanism might explain hyperglycemic effects of statins observed in clinical trials.

Cardiovascular event reduction versus new-onset diabetes during atorvastatin therapy: effect of baseline risk factors for diabetes

OBJECTIVES

The purpose of this study was to compare the incidence of new-onset diabetes (NOD) with cardiovascular (CV) event reduction at different levels of NOD risk.

BACKGROUND

Statins reduce the number of CV events but increase the incidence of NOD. We previously reported that 4 factors independently predicted NOD: fasting blood glucose >100 mg/dl, fasting triglycerides >150 mg/dl, body mass index >30 kg/m(2), and history of hypertension.

METHODS

We compared NOD incidence with CV event reduction among 15,056 patients with coronary disease but without diabetes at baseline in the TNT (Treating to New Targets) (n = 7,595) and IDEAL (Incremental Decrease in Endpoints Through Aggressive Lipid Lowering) (n = 7,461) trials. CV events included coronary heart disease death, myocardial infarction, stroke, and resuscitated cardiac arrest.

RESULTS

Among 8,825 patients with 0 to 1 of the aforementioned NOD risk factors at baseline, NOD developed in 142 of 4,407 patients in the atorvastatin 80 mg group and in 148 of 4,418 in the atorvastatin 10 mg and simvastatin 20 to 40 mg groups (3.22% vs. 3.35%; hazard ratio [HR]: 0.97; 95% confidence intervals [CI]: 0.77 to 1.22). Among the remaining 6,231 patients with 2 to 4 NOD risk factors, NOD developed in 448 of 3,128 in the atorvastatin 80 mg group and in 368 of 3,103 in the lower-dose groups (14.3% vs. 11.9%; HR: 1.24; 95% CI: 1.08 to 1.42; p = 0.0027). The number of CV events was significantly reduced with atorvastatin 80 mg in both NOD risk groups.

CONCLUSIONS

Compared with lower-dose statin therapy, atorvastatin 80 mg/day did not increase the incidence of NOD in patients with 0 to 1 NOD risk factors but did, by 24%, among patients with 2 to 4 NOD risk factors. The number of CV events was significantly reduced with atorvastatin 80 mg in both NOD risk groups.