Abstract: Cardiovascular disease (CVD) is the leading cause of death in the United States (US). One of the most important things primary care providers (PCP) can do to prevent CVD is using primary prevention treatments. In the practice where the project was implemented, a standardized process was not in place for identifying at-risk patients. Without this, there is no way to identify if providers were adequately assessing patients for atherosclerotic cardiovascular disease (ASCVD) risk by considering their risk-enhancing factors. One way to identify appropriate patients is by completing ASCVD risk calculation using the ASCVD Risk Estimator Plus from the American College of Cardiology and the American Heart Association. In addition, 2018 Guidelines for Cholesterol Management recommend ASCVD risk calculation on all patients 40-79. The use of this tool is free to both patients and providers through a website or mobile app. The calculator can be integrated into the Electronic Health Record (EHR) to improve ease of use however, that does not come standard. Therefore, ASCVD risk calculation was performed on all patients aged 40-79 presenting for a fasting lab visit (FLV) at a primary care practice comprised of 3 clinics in East Tennessee between January 17, 2022 and February 28, 2022. Excluded patients included: patients outside of the age range, who did not have a lipid level done at their FLV, or who had a total cholesterol (TC) level greater than 320mg/dL. Once calculation was performed, results were given to the patient’s PCP for medical decision making on primary prevention treatment. After providers were given the results, chart reviews were completed to assess for primary prevention treatment initiations or increases within three months of receiving the results. Preliminary results show that a total of 443 patients presented for a FLV during the timeframe. A total of 132 patients were ineligible due to age (n=70), not having a lipid level completed (n=61) or having a TC level greater than 320 mg/dL (n=1). A total of 133 patients did not show or rescheduled their FLV. Chart reviews are just beginning, and insufficient data is currently available regarding intervention results. Limitations to this project include: all participants were Caucasian therefore, result may not be applicable to a more diverse population, the project was completed during a pandemic where patients were hesitant to come into the office, even for FLV, and a considerable number of patients who risk calculation could not be completed on. Having ASCVD calculation integrated within the EHR could promote use by providers. Future long-term research is needed to identify the accuracy of this calculator. This calculator has been modified based on research. However, research to identify the accuracy could lead to modification of the calculation to provide the most accurate result possible. One way this can be done is through use of the calculator by providers across the US.

Heart disease is the leading cause of death in the United States. Hyperlipidemia is a predominant risk factor in the development of atherosclerotic cardiovascular disease (ASCVD). The statin drug class is the first line therapeutic for lowering atherogenic low-density lipoprotein (LDL) levels by competitively inhibiting 3-hydroxyl-3methyl-glutaryl-coenzyme A (HMGCR) reductase, the rate-limiting enzyme in cholesterol biosynthesis. However, there are patients who are unable to achieve desirable LDL levels despite statin therapy, such as those with familial hypercholesterolemia or those who are statin intolerant. A new therapy was discovered in 2015 to benefit patients with uncontrolled LDL levels by inhibiting Proprotein convertase subtilisin-kexin type 9 (PCSK9), a key protein in LDL receptor metabolism. Evolocumab (Repatha, AMGEN) is a human monoclonal antibody against human PSCK9. Evolocumab is approved to lower LDL-cholesterol in adult patients who have, despite dietary and lifestyle changes and maximally tolerated statin dose continued suboptimal lipid levels with either ASCVD or Heterozygous Familial Hypercholesterolemia (HeFH). Evolocumab has been shown to significantly reduce atherogenic lipid levels and the recent FOURNIER clinical trial showed that evolocumab reduces cardiovascular events. However, the high annual cost of evolocumab has raised questions as to its cost-effectiveness and role in the prevention and treatment of ASCVD. At the present price levels, this therapy does not appear to be cost-effective with multiple analyses suggesting significant price reduction will be necessary before this drug can be used in standard treatment for secondary prevention of cardiovascular disease in the United States.

Cholesterol and fatty acid homeostasis is maintained by a complex network of regulatory mechanisms that control the biosynthesis and deposition of lipids over diverse physiological conditions. However, these processes can become dysregulated and uncoupled from energy metabolism by metabolic stress such as a hyper-caloric diet and physical inactivity; eventually manifesting as risk factors associated with atherosclerotic cardiovascular disease (ASCVD), Type 2 diabetes (T2D), and/or non-alcoholic fatty liver disease (NAFLD). AMP-activated protein kinase (AMPK) is a sensor of cellular energy status that promotes metabolic homeostasis by mediating effects on multiple cellular processes including cholesterol and fatty acid synthesis biosynthesis. However, the mechanisms linking AMPK to lipid metabolism under normal and pathological conditions, remain undefined. In these studies, we identify a novel nutrient sensing mechanism whereby the coenzyme A (CoA) activated esters of long-chain fatty acids (LCFA-CoA) directly activate AMPK via specific interactions within the β1-regulatory subunit involving a Ser108 residue previously shown only with synthetic activators. We demonstrate the physiological relevance for this mechanism in an acute setting by showing that fatty acid oxidation was attenuated in mice harboring an AMPKβ1-S108A knock-in mutation compared to WT mice. We then demonstrated that β1-selctive AMPK activation is mimicked by the CoA conjugated form of bempedoic acid, a synthetic small molecule lipid synthesis inhibitor in clinical development for lowering elevated levels of low-density lipoprotein cholesterol (LDL-C). The importance of this mechanism was determined by assessing multiple disease outcomes in Ampkβ1-/-/Apoe-/- double knockout (DKO) mice fed a high fat-high cholesterol (HFHC) diet ± bempedoic acid. In these studies, bempedoic acid treatment reduced plasma LDL-C and atherosclerosis in both Apoe-/- and DKO mice, while no differences in disease outcomes was detected between the two genotypes in response to HFHC feeding. Further mechanistic investigations in rodent and primary human hepatocytes, revealed that the CoA conjugate of bempedoic acid suppressed lipid synthesis via competitive inhibition of ATP-citrate lyase (ACL), which promoted LDL receptor upregulation and associated reductions in LDL-C. We then integrate these findings with published literature in a written synthesis aimed to evaluate the role of ACL in metabolism, and its potential utility as a therapeutic target to treat ASCVD and metabolic disorders in humans. Although several questions remain regarding the metabolic role of AMPK activation by LCFA-CoAs, these studies have expanded our understanding of how cells acutely integrate lipid and energy signals to maintain lipid homeostasis, and identified ACL as a promising strategy to treat hypercholesterolemia, ASCVD, and associated metabolic disorders. / Thesis / Doctor of Philosophy (PhD) / The dysregulation of cholesterol and triglyceride metabolism can manifest as risk factors for life-threating diseases such as atherosclerotic cardiovascular diseases (ASCVD), Type-2 diabetes (T2D), and nonalcoholic fatty liver disease (NAFLD). However, the underlying mechanisms controlling lipid homeoastasis in health and disease are not completely understood. ATP-citrate lyase (ACL) and AMP-activated protein kinase (AMPK) are emerging as key nodes in metabolism that integrate lipid metabolism with signals of nutrient availability and cellular energy status, respectively. These strategic positions in metabolism suggest that both these enzymes could play an important role in the underlying pathophysiology of lipid-related diseases, and are therefore, prime candidates for therapeutic intervention. In these studies, we expand our understanding of the role of AMPK in metabolism beyond energy sensing by identifying specific lipid metabolites as direct allosteric activators of kinase activity. We also evaluate the therapeutic utility of targeting both AMPK and ACL in novel models of hypercholesterolemia and metabolic disease, and demonstrate that ACL inhibition offers a promising strategy to address multiple unmet medical needs.