Can angiotensin-converting enzyme inhibitors reverse atherosclerosis?

Effects of renin-angiotensin-aldosterone-system inhibitors on coronary atherosclerotic plaques: The PARADIGM registry

BACKGROUND AND AIMS

Inhibition of Renin-Angiotensin-Aldosterone-System (RAAS) has been hypothesized to improve endothelial function and reduce plaque inflammation, however, their impact on the progression of coronary atherosclerosis is unclear. We aim to study the effects of RAAS inhibitor on plaque progression and composition assessed by serial coronary CT angiography (CCTA).

METHODS

We performed a prospective, multinational study consisting of a registry of patients without history of CAD, who underwent serial CCTAs. Patients using RAAS inhibitors were propensity matched to RAAS inhibitor naïve patients based on clinical and CCTA characteristics at baseline. Atherosclerotic plaques in CCTAs were quantitatively analyzed for percent atheroma volume (PAV) according to plaque composition. Interactions between RAAS inhibitor use and baseline PAV on plaque progression were assessed in the unmatched cohort using a multivariate linear regression model.

RESULTS

Of 1248 patients from the registry, 299 RAAS inhibitor taking patients were matched to 299 RAAS inhibitor naïve patients. Over a mean interval of 3.9 years, there was no significant difference in annual progression of total PAV between RAAS inhibitor naïve vs taking patients (0.75 vs 0.79%/year, p = 0.66). With interaction testing in the unmatched cohort, however, RAAS inhibitor use was significantly associated with lower non-calcified plaque progression (Beta coefficient -0.100, adjusted p = 0.038) with higher levels of baseline PAV.

CONCLUSIONS

The use of RAAS inhibitors over a period of nearly 4 years did not significantly impact on total atherosclerotic plaque progression or various plaque components. However, interaction testing to assess the differential effect of RAAS inhibition based on baseline PAV suggested a significant decrease in progression of non-calcified plaque in patients with a higher burden of baseline atherosclerosis, which should be considered hypothesis generating.

Nanotechnological approach to delivering nutraceuticals as promising drug candidates for the treatment of atherosclerosis

Atherosclerosis is Caesar's sword, which poses a huge risk to the present generation. Understanding the atherosclerotic disease cycle would allow ensuring improved diagnosis, better care, and treatment. Unfortunately, a highly effective and safe way of treating atherosclerosis in the medical community remains a continuous challenge. Conventional treatments have shown considerable success, but have some adverse effects on the human body. Natural derived medications or nutraceuticals have gained immense popularity in the treatment of atherosclerosis due to their decreased side effects and toxicity-related issues. In hindsight, the contribution of nutraceuticals in imparting enhanced clinical efficacy against atherosclerosis warrants more experimental evidence. On the other hand, nanotechnology and drug delivery systems (DDS) have revolutionized the way therapeutics are performed and researchers have been constantly exploring the positive effects that DDS brings to the field of therapeutic techniques. It could be as exciting as ever to apply nano-mediated delivery of nutraceuticals as an additional strategy to target the atherosclerotic sites boasting high therapeutic efficiency of the nutraceuticals and fewer side effects.

A Study to Assess the Therapeutic Effect of Enalapril on Olanzapine Induced Metabolic Syndrome in Wistar Rats

INTRODUCTION

Metabolic Syndrome (MS) is a complex of risk factors for the development of cardiovascular complications and Type 2 Diabetes Mellitus (DM). Pharmacological management of the condition is complex, as multiple drug groups have to be used, as the syndrome itself is multi faceted. Angiotensin Converting Enzyme Inhibitors (ACEIs) are chiefly used to manage the hypertensive component of the syndrome. However, recent studies have shown that these drugs may have a role in the non hypertensive aspects of the syndrome as well.

AIM

To evaluate the therapeutic effect of enalapril on total body weight, random blood glucose and serum lipid profile in a rodent model of olanzapine induced MS.

MATERIALS AND METHODS

Three different dosages (1 mg/kg/day, 10 mg/kg/day and 20 mg/kg/day) of oral enalapril were administered (for three weeks) in albino wistar rats, which received prior intra peritoneal olanzapine (for three weeks), and compared against control (normal saline) and standard (olanzapine only and enalapril only) groups. Parameters like total body weight, random blood glucose and serum lipid profile were measured at baseline, at three weeks and at six weeks.

RESULTS

Enalapril at 20 mg/kg/day was found to be effective in reversing the weight gain, hyperglycaemia and hypercholesterolaemia, without any changes in triglycerides, High Density Lipoprotein (HDL) and Low Density Lipoprotein (LDL). 10 mg/kg/day of enalapril prevented any further rise in body weight, blood glucose, total cholesterol and serum triglycerides, after olanzapine was stopped. 1 mg/kg/day of enalapril was ineffective.

CONCLUSION

High dose of enalapril may be considered as a component of therapeutic regimens to combat weight gain, hyperglycaemia and dyslipidaemia seen in MS, in addition to its antihypertensive utility. Further rodent and clinical studies may be required to ascertain the same.

Bayesian meta-analysis of tissue angiotensin-converting enzyme inhibitors for reduction of adverse cardiovascular events in patients with diabetes mellitus and preserved left ventricular function

The role of angiotensin-converting enzyme (ACE) inhibitors in diabetic patients with preserved ventricular function is uncertain. Tissue ACE inhibitors have been defined by increased lipophilicity and structural characteristics that result in greater tissue-specific ACE binding when compared with plasma ACE inhibitors. A Bayesian meta-analysis of randomized trials was conducted to evaluate tissue ACE inhibitors in prevention of cardiovascular disease among patients with diabetes mellitus and preserved left ventricular function. Four trials were selected that evaluated 2 different ACE inhibitors and included 10,328 patients (43,517 patient-years). The Perindopril Substudy in Coronary Artery Disease and Diabetes (PERSUADE) and the Perindopril Protection Against Recurrent Stroke Study (PROGRESS) compared the effects of perindopril vs a placebo, and the Heart Outcomes Prevention Evaluation (HOPE) and the Non-Insulin-Dependent Diabetes, Hypertension, Microalbuminuria, Proteinuria, Cardiovascular Events, and Ramipril (DIABHYCAR) study investigated the impact of ramipril vs a placebo. Bayesian meta-analysis of sequential trials and sensitivity analysis of therapeutic response were subsequently computed. Bayesian meta-analysis determined reduced risk of cardiovascular mortality (PB=.991), myocardial infarction (PB=.999), and the need for invasive coronary revascularization (PB=.995) when compared with placebo. Total mortality was also decreased (PB=.967), while the risk of stroke (PB=.907) and hospitalization for heart failure (PB=.923) were impacted. Bayesian meta-analysis of randomized trials suggests that tissue ACE inhibitors decrease the probability that diabetic patients with preserved left ventricular function will experience myocardial infarctions and cardiovascular death and reduce overall mortality.

The inhibitory effect of alacepril, an angiotensin-converting enzyme inhibitor, on endothelial inflammatory response induced by oxysterol and TNF-alpha

The objectives were to determine the effects of alacepril, an angiotensin-converting enzyme inhibitor, on the expression of adhesion molecules and monocyte adherence to endothelial cells induced by 7-ketocholesterol (7-KC) and tumor necrosis factor (TNF)-alpha. We used human aortic endothelial cells (HAECs) and U937 monocytic cells. Surface expression and mRNA levels of intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1) were determined by EIA and RT-PCR. Adherence of U937 to HAECs was assessed by adhesion assay. Incubation of HAEC with 7-KC increased the surface expression of protein and mRNA levels of ICAM-1 and VCAM-1 on HAECs and the production of reactive oxygen species (ROS) in HAECs. Pretreatment with alacepril reduced the enhanced expression of these molecules in a dose-dependent manner. The inhibitory effect of alacepril against 7-KC or TNF-alpha-induced CAMs expression was stronger than that of captopril or enalapril. Alacepril inhibited the production of ROS in HAECs stimulated by 7-KC or TNF-alpha. These results suggest that alacepril works as anti-atherogenic agent through inhibiting endothelial-dependent adhesive interactions with monocytes induced by 7-KC and TNF-alpha.

ACE inhibitors in heart failure: what more do we need to know?

ACE inhibitors have significantly decreased cardiovascular mortality, myocardial infarction (MI), and hospitalizations for heart failure (HF) in patients with asymptomatic or symptomatic left ventricular (LV) systolic dysfunction. Furthermore, the extended 12-year study of the SOLVD (Studies Of Left Ventricular Dysfunction) Prevention and Treatment trials (X-SOLVD) demonstrated a significant benefit with a reduction of cumulative all-cause death compared with placebo (50.9% vs 56.4%) [hazard ratio (HR) 0.86; 95% CI 0.79, 0.93; p < 0.001]. The survival benefits and significant reductions in cardiovascular morbidity related to treatment with ACE inhibitors are likely achieved by titrating the dose of ACE inhibitors to the target dose achieved in clinical trials. Although the ATLAS (Assessment of Treatment with Lisinopril And Survival) study, which randomly allocated HF patients to low- or high-dose lisinopril, showed no significant difference between groups for the primary outcome of all-cause mortality (HR 0.92; 95% CI 0.82, 1.03), the predetermined secondary combined outcome of all-cause mortality and HF hospitalization was reduced by 15% for the patients receiving high-dose lisinopril compared with low-dose (p < 0.001) with a 24% reduction in HF hospitalization (p = 0.002). Despite the use of ACE inhibitors, blockade of the renin angiotensin aldosterone system (RAAS) remains incomplete, with evidence of continued production of angiotensin II by non-ACE-dependent pathways. The safety and potential benefits of angiotensin receptor antagonists (angiotensin receptor blockers [ARBs]) in patients with impaired systolic function have been assessed in moderate to large clinical trials. In patients with impaired LV systolic function and HF, combination therapy with ARBs with recommended HF therapy including ACE inhibitors in patients who remain symptomatic may be considered for its morbidity benefit. Based on the CHARM (Candesartan in Heart failure: Assessment of Reduction in Mortality and morbidity)-Added data, candesartan cilexetil in addition to standard HF therapy results in a further reduction of cardiovascular mortality. Close monitoring of renal function and serum potassium levels is needed in this setting. The VALIANT (VALsartan In Acute myocardial iNfarction Trial) results suggest that valsartan is as effective as captopril in patients following an acute MI with HF and/or LV systolic dysfunction and may be used as an alternative treatment in ACE inhibitor-intolerant patients. There was no survival benefit with valsartan-captopril combination compared with captopril alone in this trial. Despite these results, ACE inhibitors remain the first-choice therapeutic agent in post-MI patients, and ARBs can be used in patients with clear intolerance. Although the use of ACE inhibitors may be appealing in patients with HF and preserved LV systolic function, there is currently no evidence from large clinical trials to support this.