Oikonomou, Evangelos

Abstract:Coronary artery disease is the leading cause of morbidity and mortality worldwide, espe-cially in developed countries, with an increasing incidence in developing countries. Despite the ad-vances in cardiology, there are yet many unanswered questions about the natural history of coronary atherosclerosis. However, it has not been fully explained why some coronary artery plaques remain quiescent over time, whereas others evolve to a high-risk, “vulnerable” plaque with a predisposition to destabilize and induce a cardiac event. Furthermore, approximately half of the patients with acute coronary syndromes demonstrate no prior symptoms of ischemia or angiographically evident dis-ease. Recent findings have indicated that apart from cardiovascular risk factors, genetics, and other unknown factors, local hemodynamic forces, such as endothelial shear stress, blood flow patterns, and endothelial dysfunction of the epicardial and microvascular coronary arteries, are associated with the progression of coronary plaque and the development of cardiovascular complications with complex interactions. In this review article, we summarize the mechanisms that affect coronary ar-tery plaque progression, indicating the importance of endothelial shear stress, endothelial dysfunc-tion of epicardial and microvascular vessels, inflammation, and their complex associations, underly-ing in parallel the clinical perspectives of these findings.

Contrast-induced nephropathy (CIN) is a type of acute kidney injury associated with intravascular administration of iodinated contrast, usually reversible. Contrast agents are an essential component of invasive and noninvasive coronary angiography. These agents have been modified over time to enhance patient safety and tolerability, but adverse reactions still occur. CIN has been variably defined, as a rise in serum creatinine of 0.5 mg/dl, or a 25% increase in serum creatinine above baseline within 24-72 hours after the procedure. The incidence of CIN varies based on the definition used and risk profile of the patients. CIN is rare among patients with normal renal function at baseline. In low-risk patients, CIN occurs in 1-5%, whereas in higher-risk populations, the incidence can be as high as 30%. CIN is also associated with a 5- to 20-fold increased risk of other early adverse events including in-hospital myocardial infarction, target vessel occlusion, and early mortality. The main prevention strategies are adequate intravenous hydration before, during and after the procedure as well as restriction of contrast load with maximum volume approximately no more than three times the serum creatinine clearance. Recent observational and small prospective randomized trials demonstrate the reduction of CIN incidence with HMG-CoA enzyme inhibitors. In this systematic review and meta-analysis we explore the effects of statin administration in prevention of CIN.

Background: Chronic inflammation and immune system activation underlie a variety of seemingly unrelated cardiac conditions including not only atherosclerosis and the subsequent coronary artery disease but also peripheral artery disease, hypertension with target organ damage and heart failure. The beneficial effects of HMG-CoA reductase inhibitors or statins are mainly attributed to their ability to inhibit hepatic cholesterol biosynthesis. Beyond their lipid lowering activity, ample evidence exists in support of their potent anti-inflammatory properties which initiate from the inhibition of GTPase isoprenylation, activating a cataract of secondary pathways and extend to the inhibition and blocking of immune cell activation and interaction. </P><P> Objective: To summarize the anti-inflammatory mechanisms of statins in clinical and experimental settings in cardiovascular disease. </P><P> Methods: A systematic search of PubMed and the Cochrane Database was conducted in order to identify the majority of trials, studies, current guidelines and novel articles related to the subject. </P><P> Results: In vitro, statins have immuno-modulatory and anti-inflammatory effects, and they can exert antiatherosclerotic effects independently of their hypolipidemic actions. In addition, positive results have emerged from mechanistic and experimental studies on the active role of HMG-CoA reductase inhibitors in HF. By extrapolating those data in clinical setting, we further understand how HMG-CoA reductase inhibitors can beneficially affect not only systolic but also diastolic HF. </P><P> Conclusion: In this review article, we present the basic pathophysiologic data supporting the anti-inflammatory actions of statins in clinical and experimental settings and we link these mechanisms with confirmatory clinical data on the potent non lipid lowering effects of HMG-CoA reductase inhibitors.