Low-dose statin therapy improves endothelial function in type 2 diabetic patients with normal serum total cholesterol: a randomized placebo-controlled study

Pharmacological effects of statins in adult patients with type 2 diabetes mellitus: A protocol for systematic review and meta-analysis

BACKGROUND

Due to contradicting findings on impact of statins on endothelial function in type 2 diabetes mellitus especially across the randomized controlled trials (RCTs). With this systematic review, we aim to evaluate whether the use of statins improves endothelial function in adults with type 2 diabetes. We will further highlight if these biomarkers are ideal therapeutic targets for risk for atherosclerosis and cardiovascular disease.

METHODS

This protocol was carried out according to the preferred reporting items for systematic review and meta-analysis protocols-2015 guideline. The online databases, such as MEDLINE, Scopus, and Web of Sciences, will be targeted using the medical subject heading terms (MeSH) and text words. The review will include clinical studies on the effect of statins on markers of endothelial function in type 2 diabetes. The Cochrane risk of bias guideline will be used to assess the quality and risk of bias. We are planning to use the grading of recommendation assessment, development, and evaluation approach to evaluate the strength and quality of evidence.

RESULTS

This study will not involve human samples and patient data; hence ethics approval will not be required. The findings will be presented in journal clubs and conferences and published in peer-reviewed journals.

Statins in patients with COVID-19: a retrospective cohort study in Iranian COVID-19 patients

BACKGROUND

The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has profoundly affected the lives of millions of people. To date, there is no approved vaccine or specific drug to prevent or treat COVID-19, while the infection is globally spreading at an alarming rate. Because the development of effective vaccines or novel drugs could take several months (if not years), repurposing existing drugs is considered a more efficient strategy that could save lives now. Statins constitute a class of lipid-lowering drugs with proven safety profiles and various known beneficial pleiotropic effects. Our previous investigations showed that statins have antiviral effects and are involved in the process of wound healing in the lung. This triggered us to evaluate if statin use reduces mortality in COVID-19 patients.

RESULTS

After initial recruitment of 459 patients with COVID-19 (Shiraz province, Iran) and careful consideration of the exclusion criteria, a total of 150 patients, of which 75 received statins, were included in our retrospective study. Cox proportional-hazards regression models were used to estimate the association between statin use and rate of death. After propensity score matching, we found that statin use appeared to be associated with a lower risk of morbidity [HR = 0.85, 95% CI = (0.02, 3.93), P = 0.762] and lower risk of death [(HR = 0.76; 95% CI = (0.16, 3.72), P = 0.735)]; however, these associations did not reach statistical significance. Furthermore, statin use reduced the chance of being subjected to mechanical ventilation [OR = 0.96, 95% CI = (0.61-2.99), P = 0.942] and patients on statins showed a more normal computed tomography (CT) scan result [OR = 0.41, 95% CI = (0.07-2.33), P = 0.312].

CONCLUSIONS

Although we could not demonstrate a significant association between statin use and a reduction in mortality in patients with COVID19, we do feel that our results are promising and of clinical relevance and warrant the need for prospective randomized controlled trials and extensive retrospective studies to further evaluate and validate the potential beneficial effects of statin treatment on clinical symptoms and mortality rates associated with COVID-19.

Triglyceride and Triglyceride/ HDL (High Density Lipoprotein) Ratio Predict Major Adverse Cardiovascular Outcomes in Women With Non-Obstructive Coronary Artery Disease

Background

Women with non‐obstructive coronary artery disease have increased cardiovascular morbidity. The role of risk factors in this population has yet to be established. We aimed to study the predictive effect of triglycerides and the triglyceride/high‐density lipoprotein ratio on major adverse cardiovascular events (MACE) in patients with non‐obstructive coronary artery disease, and to explore the role of lipid lowering therapy in modifying this risk.

Methods and Results

This is a prospective cohort study enrolling patients with anginal symptoms referred to the cardiac catheterization laboratory for suspected ischemia, who were subsequently diagnosed with non‐obstructive coronary artery disease, defined as no stenosis >20% on angiography. All patients had baseline laboratory testing and were followed for 7.8±4.3 years for the development of major adverse cardiovascular events. We performed Cox proportional hazard testing to determine the effect of triglycerides on risk of major adverse cardiovascular events among men and women by baseline statin use. A total of 462 patients were included. Median age was 53 (Q1, Q3: 45, 62) years. In a Cox proportional hazard model stratified by statin use adjusting for confounders, among those not on baseline statins, triglycerides were independently predictive of major adverse cardiovascular events in women (per 50 mg/dL risk ratio: hazard ratio 1.25 [95% CI: 1.06, 1.47]; P=0.01). This was not true among men. The interaction between triglycerides and sex, and triglycerides and statin was statistically significant.

Conclusions

Triglyceride levels may play a key role in predicting cardiovascular‐specific risk in women, and statin use may be protective. Further investigation is necessary to better delineate the role of statin use in preventing cardiovascular risk.

Survival Time of Visual Gains after Diabetic Vitrectomy and Its Relationship with Ischemic Heart Disease

Vitrectomy surgery in proliferative diabetic retinopathy improves the vision-related quality of life. However, there is lack of data on the duration of maintenance of visual gains post vitrectomy. This study thus aimed to determine the survival time of visual gains and the prognostic factors of vision loss after vitrectomy surgery for complications of proliferative diabetic retinopathy. A retrospective cohort study was conducted in an ophthalmology clinic in Malaysia. We included 134 patients with type 2 diabetes mellitus on follow-up after vitrectomy for proliferative diabetic retinopathy. Visual acuity was measured using the log of minimum angle of resolution (LogMar). A gain of ≥0.3 LogMar sustained on two subsequent visits was considered evidence of visual improvement post vitrectomy. Subjects were considered to have vision loss when their post-operative visual acuity subsequently dropped by ≥0.3 LogMar. Kaplan–Meier analysis was used to determine the survival time of visual gains. Cox Proportional Hazard regression was used to determine the prognostic factors of vision loss. The median age of patients was 56.00 years (IQR ± 10.00). The median duration of diabetes mellitus was 14.00 years (IQR ± 10.00). Approximately 50% of patients with initial improvement post vitrectomy subsequently experienced vision loss. The survival time, i.e., the median time from surgery until the number of patients with vision loss formed half of the original cohort, was 14.63 months (95% CI: 9.95, 19.32). Ischemic heart disease was a significant prognostic factor of vision loss. Patients with underlying ischemic heart disease (adjusted HR: 1.97, 95% CI: 1.18, 3.33) had a higher risk of vision loss post vitrectomy, after adjusting for other factors. Approximately half the patients with initial visual gains post vitrectomy maintained their vision for at least one year. Ischemic heart disease was a poor prognostic factor for preservation of visual gains post vitrectomy.

Chronic administration of atorvastatin could partially ameliorate erectile function in streptozotocin-induced diabetic rats

The efficacy of statins is related to the ‘common soil’ hypothesis, which proposes oxidative stress and inflammation as main pathophysiologic processes in the disease group of diabetes and endothelial dysfunction. This study evaluated the recovery of erectile function after administration of chronic statin alone in streptozotocin (STZ)-induced diabetes mellitus (DM) rats, focusing on the anti-oxidative effects and consequentially recuperated endothelial function. A total of 45 male Sprague-Dawley rats (8 weeks old) were divided into three groups (n = 15 each): an age-matched normal control group (Control group), an uncontrolled DM group (DM group), and a statin-treated group (Statin group). The rats in the DM and Statin group received an injection of STZ (60 mg/kg). Beginning 10 weeks after the establishment of DM, the Statin group received daily treatment with atorvastatin (10 mg/kg) via oral gavage for four weeks. After 14 weeks, the results of the experiment were evaluated. The ratios of intracavernosal pressure (ICP) to mean arterial pressure (MAP) were recorded with cavernosometry (20 Hz, 3 V, 0.2 msec for 30 seconds) before and after the intravenous administration of udenafil (1 mg/kg). Expression of alpha-smooth muscle actin (α-SMA) was evaluated using cavernosal tissue. In addition, changes in RhoA translocation ratio and myosin phosphatase target subunit 1 (MYPT1) phosphorylation were evaluated with western blot. Superoxide dismutase (SOD) and malondialdehyde (MDA) levels were also analyzed as measurements of oxidative stress levels. The ICP/MAP and area under the curve (AUC)/MAP ratios of the Statin group were obviously superior to the DM group, but were not comparable to the Control group (P<0.001). The level of oxidative stress, namely SOD activity, was also significantly lower in the Statin group than in the DM group (P = 0.015), and was comparable to the Control group. In contrast, MDA levels were not considerably different among the groups (P = 0.217). The RhoA translocation ratio was not significantly different among the groups (P = 0.668), whereas MYPT1 phosphorylation in the Statin group was significantly lower than in the DM group (P = 0.030), and similar to the Control group. Expression of α-SMA in the Statin group was higher than in the DM group (P<0.001), and comparable to the Control group. Chronic statin treatment alone showed anti-oxidative effects and helped to restore the erectile mechanism, but did not lead to the full recovery of erectile function in STZ-induced DM rats. Therefore, combination therapy rather than a single agent should be the preferred treatment strategy for DM-associated erectile dysfunction, especially in the setting of severe diabetes.

Endothelial dysfunction in diabetes: pathogenesis, significance, and treatment

Type 2 diabetes (T2D) markedly increases the risk of cardiovascular disease. Endothelial dysfunction (ED), an early indicator of diabetic vascular disease, is common in T2D and independently predicts cardiovascular risk. Although the precise pathogenic mechanisms for ED in T2D remain unclear, at inception they probably involve uncoupling of both endothelial nitric oxide synthase activity and mitochondrial oxidative phosphorylation, as well as the activation of vascular nicotinamide adenine dinucleotide phosphate oxidase. The major contributing factors include dyslipoproteinemia, oxidative stress, and inflammation. Therapeutic interventions are designed to target these pathophysiological factors that underlie ED. Therapeutic interventions, including lifestyle changes, antiglycemic agents and lipid-regulating therapies, aim to correct hyperglycemia and atherogenic dyslipidemia and to improve ED. However, high residual cardiovascular risk is seen in both research and clinical practice settings. Well-designed studies of endothelial function in appropriately selected volunteers afford a good opportunity to test new therapeutic interventions, paving the way for clinical trials and utilization in the care of the diabetic patient. However, based on the results from a recent clinical trial, niacin should not be added to a statin in individuals with low high-density lipoprotein cholesterol and very well controlled low-density lipoprotein cholesterol.

Dyslipidemia is associated with sympathetic nervous activation and impaired endothelial function in young females

BACKGROUND

Dyslipidemia is one the most well-established risk factors for cardiovascular disease development. Moreover, hypercholesterolemia and plasma cholesterol level in the high to normal range are established triggers for impairment in endothelial function. Evidence indicates that endothelial function is closely linked with sympathetic nervous activity in healthy individuals. We therefore investigated whether both endothelial and sympathetic functions may be impaired in young females with abnormal plasma cholesterol levels.

METHODS

Baseline endothelial function (digital pulse amplitude) and muscle sympathetic nervous activity (microneurography) were retrospectively analyzed in 14 young healthy females with dyslipidemia as indicated by total cholesterol ≥197mg/dL, high-density lipoprotein ≤39mg/dL, or low-density lipoprotein >116mg/dL, and in 13 females with lipids in the healthy range.

RESULTS

Subjects with dyslipidemia had significantly impaired endothelial function compared to those with a normal cholesterol profile (reactive hyperemia index; 1.61±0.10 vs. 2.32±0.14, P < 0.001), increased muscle sympathetic nervous activity (after adjusting for body mass and age, 36±3 vs. 27±3 bursts per 100 heartbeats, P = 0.049) and elevated high-sensitivity C-reactive protein (4.13±0.77 vs. 1.92±0.61mg/L, P = 0.03).

DISCUSSION

Our results indicate that young healthy females with dyslipidemia present with a strong impairment of endothelial function and increased sympathetic drive. The sympathetic activation observed in the subjects with an elevated cholesterol profile may play a role in the development of cardiovascular disease development.