Potent lipoprotein(a) lowering following apolipoprotein(a) antisense treatment reduces the pro-inflammatory activation of circulating monocytes in patients with elevated lipoprotein(a).

AIMS: Elevated lipoprotein(a) [Lp(a)] is strongly associated with an increased cardiovascular disease (CVD) risk. We previously reported that pro-inflammatory activation of circulating monocytes is a potential mechanism by which Lp(a) mediates CVD. Since potent Lp(a)-lowering therapies are emerging, it is of interest whether patients with elevated Lp(a) experience beneficial anti-inflammatory effects following large reductions in Lp(a). METHODS AND RESULTS: Using transcriptome analysis, we show that circulating monocytes of healthy individuals with elevated Lp(a), as well as CVD patients with increased Lp(a) levels, both have a pro-inflammatory gene expression profile. The effect of Lp(a)-lowering on gene expression and function of monocytes was addressed in two local sub-studies, including 14 CVD patients with elevated Lp(a) who received apolipoprotein(a) [apo(a)] antisense (AKCEA-APO(a)-LRx) (NCT03070782), as well as 18 patients with elevated Lp(a) who received proprotein convertase subtilisin/kexin type 9 antibody (PCSK9ab) treatment (NCT02729025). AKCEA-APO(a)-LRx lowered Lp(a) by 47% and reduced the pro-inflammatory gene expression in monocytes of CVD patients with elevated Lp(a), which coincided with a functional reduction in transendothelial migration capacity of monocytes ex vivo (-17%, P < 0.001). In contrast, PCSK9ab treatment lowered Lp(a) by 16% and did not alter transcriptome nor functional properties of monocytes, despite an additional reduction of 65% in low-density lipoprotein cholesterol (LDL-C). CONCLUSION: Potent Lp(a)-lowering following AKCEA-APO(a)-LRx, but not modest Lp(a)-lowering combined with LDL-C reduction following PCSK9ab treatment, reduced the pro-inflammatory state of circulating monocytes in patients with elevated Lp(a). These ex vivo data support a beneficial effect of large Lp(a) reductions in patients with elevated Lp(a).

Persistent arterial wall inflammation in patients with elevated lipoprotein(a) despite strong low-density lipoprotein cholesterol reduction by proprotein convertase subtilisin/kexin type 9 antibody treatment.

AIMS: Subjects with lipoprotein(a) [Lp(a)] elevation have increased arterial wall inflammation and cardiovascular risk. In patients at increased cardiovascular risk, arterial wall inflammation is reduced following lipid-lowering therapy by statin treatment or lipoprotein apheresis. However, it is unknown whether lipid-lowering treatment in elevated Lp(a) subjects alters arterial wall inflammation. We evaluated whether evolocumab, which lowers both low-density lipoprotein cholesterol (LDL-C) and Lp(a), attenuates arterial wall inflammation in patients with elevated Lp(a). METHODS AND RESULTS: In this multicentre, randomized, double-blind, placebo-controlled study, 129 patients {median [interquartile range (IQR)]: age 60.0 [54.0-67.0] years, Lp(a) 200.0 [155.5-301.5] nmol/L [80.0 (62.5-121.0) mg/dL]; mean [standard deviation (SD)] LDL-C 3.7 [1.0] mmol/L [144.0 (39.7) mg/dL]; National Cholesterol Education Program high risk, 25.6%} were randomized to monthly subcutaneous evolocumab 420 mg or placebo. Compared with placebo, evolocumab reduced LDL-C by 60.7% [95% confidence interval (CI) 65.8-55.5] and Lp(a) by 13.9% (95% CI 19.3-8.5). Among evolocumab-treated patients, the Week 16 mean (SD) LDL-C level was 1.6 (0.7) mmol/L [60.1 (28.1) mg/dL], and the median (IQR) Lp(a) level was 188.0 (140.0-268.0) nmol/L [75.2 (56.0-107.2) mg/dL]. Arterial wall inflammation [most diseased segment target-to-background ratio (MDS TBR)] in the index vessel (left carotid, right carotid, or thoracic aorta) was assessed by 18F-fluoro-deoxyglucose positron-emission tomography/computed tomography. Week 16 index vessel MDS TBR was not significantly altered with evolocumab (-8.3%) vs. placebo (-5.3%) [treatment difference -3.0% (95% CI -7.4% to 1.4%); P = 0.18]. CONCLUSION: Evolocumab treatment in patients with median baseline Lp(a) 200.0 nmol/L led to a large reduction in LDL-C and a small reduction in Lp(a), resulting in persistent elevated Lp(a) levels. The latter may have contributed to the unaltered arterial wall inflammation.

Cardiovascular disease risk associated with elevated lipoprotein(a) attenuates at low low-density lipoprotein cholesterol levels in a primary prevention setting.

Aims: Lipoprotein(a) (Lp(a)) elevation is a causal risk factor for cardiovascular disease (CVD). It has however been suggested that elevated Lp(a) causes CVD mainly in individuals with high low-density lipoprotein cholesterol (LDL-C) levels. We hypothesized that the risk associated with high Lp(a) levels would largely be attenuated at low LDL-C levels. Methods and results: In 16 654 individuals from the EPIC-Norfolk prospective population study, and in 9448 individuals from the Copenhagen City Heart Study (CCHS) parallel statistical analyses were performed. Individuals were categorized according to their Lp(a) and LDL-C levels. Cut-offs were set at the 80th cohort percentile for Lp(a). Low-density lipoprotein cholesterol cut-offs were set at 2.5, 3.5, 4.5, and 5.5 mmol/L. Low-density lipoprotein cholesterol levels in the primary analyses were corrected for Lp(a)-derived LDL-C (LDL-Ccorr). Multivariable-adjusted hazard ratios were calculated for each category. The category with LDL-Ccorr <2.5 mmol/L and Lp(a) <80th cohort percentile was used as reference category. In the EPIC-Norfolk and CCHS cohorts, individuals with an Lp(a) ≥80th percentile were at increased CVD risk compared with those with Lp(a) <80th percentile for any LDL-Ccorr levels ≥2.5 mmol/L. In contrast, for LDL-Ccorr <2.5 mmol/L, the risk associated with elevated Lp(a) attenuated. However, there was no interaction between LDL-Ccorr and Lp(a) levels on CVD risk in either cohort. Conclusion: Lipoprotein(a) and LDL-C are independently associated with CVD risk. At LDL-C levels below <2.5 mmol/L, the risk associated with elevated Lp(a) attenuates in a primary prevention setting.

Prolonged hematopoietic and myeloid cellular response in patients after an acute coronary syndrome measured with 18F-DPA-714 PET/CT.

PURPOSE: An acute coronary syndrome (ACS) is characterized by a multi-level inflammatory response, comprising activation of bone marrow and spleen accompanied by augmented release of leukocytes into the circulation. The duration of this response after an ACS remains unclear. Here, we assessed the effect of an ACS on the multi-level inflammatory response in patients both acutely and after 3 months. METHODS: We performed 18F-DPA-714 PET/CT acutely and 3 months post-ACS in eight patients and eight matched healthy controls. DPA-714, a PET tracer binding the TSPO receptor and highly expressed in myeloid cells, was used to assess hematopoietic activity. We also characterized circulating monocytes and hematopoietic stem and progenitor cells (HSPCs) by flow cytometry in 20 patients acutely and 3 months post-ACS and in 19 healthy controls. RESULTS: In the acute phase, patients displayed a 1.4-fold and 1.3-fold higher 18F-DPA-714 uptake in, respectively, bone marrow (p = 0.012) and spleen (p = 0.039) compared with healthy controls. This coincided with a 2.4-fold higher number of circulating HSPCs (p = 0.001). Three months post-ACS, 18F-DPA-714 uptake in bone marrow decreased significantly (p = 0.002), but no decrease was observed for 18F-DPA-714 uptake in the spleen (p = 0.67) nor for the number of circulating HSPCs (p = 0.75). CONCLUSIONS: 18F-DPA-714 PET/CT reveals an ACS- triggered hematopoietic organ activation as initiator of a prolonged cellular inflammatory response beyond 3 months, characterized by a higher number of circulating leukocytes and their precursors. This multi-level inflammatory response may provide an attractive target for novel treatment options aimed at reducing the high recurrence rate post-ACS.

Remnant Cholesterol Elicits Arterial Wall Inflammation and a Multilevel Cellular Immune Response in Humans.

OBJECTIVE: Mendelian randomization studies revealed a causal role for remnant cholesterol in cardiovascular disease. Remnant particles accumulate in the arterial wall, potentially propagating local and systemic inflammation. We evaluated the impact of remnant cholesterol on arterial wall inflammation, circulating monocytes, and bone marrow in patients with familial dysbetalipoproteinemia (FD). APPROACH AND RESULTS: Arterial wall inflammation and bone marrow activity were measured using 18F-FDG PET/CT. Monocyte phenotype was assessed with flow cytometry. The correlation between remnant levels and hematopoietic activity was validated in the CGPS (Copenhagen General Population Study). We found a 1.2-fold increase of 18F-FDG uptake in the arterial wall in patients with FD (n=17, age 60±8 years, remnant cholesterol: 3.26 [2.07-5.71]) compared with controls (n=17, age 61±8 years, remnant cholesterol 0.29 [0.27-0.40]; P<0.001). Monocytes from patients with FD showed increased lipid accumulation (lipid-positive monocytes: Patients with FD 92% [86-95], controls 76% [66-81], P=0.001, with an increase in lipid droplets per monocyte), and a higher expression of surface integrins (CD11b, CD11c, and CD18). Patients with FD also exhibited monocytosis and leukocytosis, accompanied by a 1.2-fold increase of 18F-FDG uptake in bone marrow. In addition, we found a strong correlation between remnant levels and leukocyte counts in the CGPS (n=103 953, P for trend 5×10-276). In vitro experiments substantiated that remnant cholesterol accumulates in human hematopoietic stem and progenitor cells coinciding with myeloid skewing. CONCLUSIONS: Patients with FD have increased arterial wall and cellular inflammation. These findings imply an important inflammatory component to the atherogenicity of remnant cholesterol, contributing to the increased cardiovascular disease risk in patients with FD.

Arterial and Cellular Inflammation in Patients with CKD.

CKD associates with a 1.5- to 3.5-fold increased risk for cardiovascular disease. Both diseases are characterized by increased inflammation, and in patients with CKD, elevated C-reactive protein level predicts cardiovascular risk. In addition to systemic inflammation, local arterial inflammation, driven by monocyte-derived macrophages, predicts future cardiovascular events in the general population. We hypothesized that subjects with CKD have increased arterial and cellular inflammation, reflected by 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography computed tomography (PET/CT) of the arterial wall and a migratory phenotype of monocytes. We assessed 18F-FDG uptake in the arterial wall in 14 patients with CKD (mean±SD age: 59±5 years, mean±SD eGFR: 37±12 ml/min per 1.73 m2) but without cardiovascular diseases, diabetes, or inflammatory conditions and in 14 control subjects (mean age: 60±11 years, mean eGFR: 86±16 ml/min per 1.73 m2). Compared with controls, patients with CKD showed increased arterial inflammation, quantified as target-to-background ratio (TBR) in the aorta (TBRmax: CKD, 3.14±0.70 versus control, 2.12±0.27; P=0.001) and the carotid arteries (TBRmax: CKD, 2.45±0.65 versus control, 1.66±0.27; P<0.001). Characterization of circulating monocytes using flow cytometry revealed increased chemokine receptor expression and enhanced transendothelial migration capacity in patients with CKD compared with controls. In conclusion, this increased arterial wall inflammation, observed in patients with CKD but without overt atherosclerotic disease and with few traditional risk factors, may contribute to the increased cardiovascular risk associated with CKD. The concomitant elevation of monocyte activity may provide novel therapeutic targets for attenuating this inflammation and thereby preventing CKD-associated cardiovascular disease.

Increased haematopoietic activity in patients with atherosclerosis.

Aims: Experimental work posits that acute ischaemic events trigger haematopoietic activity, driving monocytosis, and atherogenesis. Considering the chronic low-grade inflammatory state in atherosclerosis, we hypothesized that haematopoietic hyperactivity is a persistent feature in cardiovascular disease (CVD). Therefore, we aimed to assess the activity of haematopoietic organs and haematopoietic stem and progenitor cells (HSPCs) in humans. Methods and results: First, we performed 18F-fluorodeoxyglucose positron emission tomographic (18F-FDG PET) imaging in 26 patients with stable atherosclerotic CVD (ischaemic event >12 months ago), and 25 matched controls. In splenic tissue, 18F-FDG uptake was 2.68 ± 0.65 in CVD patients vs. 1.75 ± 0.54 in controls (1.6-fold higher; P< 0.001), and in bone marrow 3.20 ± 0.76 vs. 2.72 ± 0.46 (1.2-fold higher; P = 0.003), closely related to LDL cholesterol levels (LDLc, r = 0.72). Subsequently, we determined progenitor potential of HSPCs harvested from 18 patients with known atherosclerotic CVD and 30 matched controls; both groups were selected from a cohort of cancer patients undergoing autologous stem cell transplantation. In CVD patients, the normalized progenitor potential, expressed as the number of colony-forming units-granulocyte/monocyte (CFU-GM) colonies/CD34+ cell, was 1.6-fold higher compared with matched controls (P < 0.001). Finally, we assessed the effects of native and oxidized lipoproteins on HSPCs harvested from healthy donors in vitro. Haematopoietic stem and progenitor cells displayed a 1.5-fold increased CFU-GM capacity in co-culture with oxidized LDL in vitro (P = 0.002), which was inhibited by blocking oxidized phospholipids via E06 (P = 0.001). Conclusion: Collectively, these findings strengthen the case for a chronically affected haematopoietic system, potentially driving the low-grade inflammatory state in patients with atherosclerosis.

Increased arterial wall inflammation in patients with ankylosing spondylitis is reduced by statin therapy.

BACKGROUND: Ankylosing spondylitis (AS) is a chronic inflammatory disease with involvement of axial and sacroiliac joints. In addition, patients with AS have increased risk of cardiovascular disease (CVD), which might be attributed to enhanced inflammatory activity of the arterial wall. In the present study, we compared the level of carotid arterial wall inflammation in patients with AS with healthy controls using (18)F-fluorodeoxyglucose ((18)F-FDG) positron emission tomography with CT. As arterial wall inflammation is reduced by statin therapy, we subsequently assessed the effect of 3-month statin therapy on arterial wall inflammation in AS. METHODS AND RESULTS: We included 24 patients with AS (age 44±10, 72% males) without a history of CVD and 20 controls matched for age and gender. Patients with AS had lower high-density lipoprotein cholesterol and increased C reactive protein (CRP) compared with controls. The 10-year CVD risk was 2% in both groups. Notwithstanding, patients with AS had a 20% increase in arterial wall (18)F-FDG uptake compared with controls. Three-month atorvastatin 40 mg daily significantly lowered low-density lipoprotein cholesterol (baseline 3.55±1.15 mmol/L, -53%) and CRP (baseline 5.0 (1.5-9.3) mg/L, -58%) with a concomitant decrease of carotid arterial wall inflammation (maximum target-to-background ratio from 1.90±0.30 to 1.67±0.27; p=0.009). CONCLUSIONS: Patients with AS and without other CVD risk factors have increased arterial wall inflammation, which decreases upon statin therapy. These subjects are not identified as being at risk in current cardiovascular prevention guidelines. Our data support the need to revise CV disease management in AS, with perhaps a role for early statin therapy.

Carotid arterial wall inflammation in peripheral artery disease is augmented by type 2 diabetes: a cross-sectional study.

BACKGROUND: Patients with peripheral artery disease (PAD) are at increased risk of secondary events, which is exaggerated in the presence of type 2 diabetes mellitus. Diabetes is associated with a systemic pro-inflammatory state. We therefore investigated the cumulative impact of PAD and type 2 diabetes on carotid arterial wall inflammation. As recent data suggest a detrimental role of exogenous insulin on cardiovascular disease, we also included a group of insulin users. RESULTS: 18F-fluorodeoxyglucose positron emission tomography with computed tomography (18F-FDG PET/CT) imaging showed increased carotid arterial wall inflammation, assessed as target-to-background ratio (TBR), in PAD patients without diabetes (PAD-only: n = 11, 1.97 ± 0.57) compared with matched controls (n = 12, 1.49 ± 0.57; p = 0.009), with a significant further TBR increase in PAD patients with type 2 diabetes (PAD-DM, n = 23, 2.90 ± 1, p = 0.033 vs PAD-only). TBR of insulin users (n = 12, 3.31 ± 1.14) was higher compared with patients on oral medication only (n = 11, 2.44 ± 0.76, p = 0.035), despite comparable PAD severity (Fontaine stages), BMI and CRP. Multivariate regression analysis showed that Hba1c and plasma insulin levels, but not dose of exogenous insulin, correlated with TBR. CONCLUSIONS: Concurrent diabetes significantly augments carotid arterial wall inflammation in PAD patients. A further increase in those requiring insulin was observed, which was associated with diabetes severity, rather than with the use of exogenous insulin itself.

Novel directions in inflammation as a therapeutic target in atherosclerosis.

PURPOSE OF REVIEW: Atherosclerosis is a chronic disease of the arterial wall largely driven by inflammation; hence, therapeutics targeting inflammatory pathways are considered an attractive strategy in atherosclerotic cardiovascular disease (ASCVD). The purpose of this review is to describe the randomized, placebo-controlled clinical trials currently investigating the impact of anti-inflammatory strategies in ASCVD patients, to discuss novel insights and targets into the role of innate immunity in atherosclerosis and to address the promise of local drug delivery as opposed to systemic therapies in atherosclerotic disease. RECENT FINDINGS: The first clinical trials using systemic anti-inflammatory drugs in ASCVD patients might be able to strengthen the case for immunomodulation once showing an improved ASCVD outcome. Several specific targets in innate immunity bear therapeutic potential, of which some have already entered the clinical arena. To prevent immunosuppression by systemic effects, drug delivery systems are increasingly being applied to locally attenuate plaque inflammation. SUMMARY: Anti-inflammatory therapies seem promising for future treatment of ASCVD. In view of the risk of immunosuppression in case of long term and systemic use of anti-inflammatory drugs, there is a clinical need for highly selective and targeted therapies in patients with atherosclerosis.

Atorvastatin treatment does not abolish inflammatory mediated cardiovascular risk in subjects with chronic kidney disease.

Individuals with chronic kidney disease are at an increased risk for cardiovascular disease. This risk may partially be explained by a chronic inflammatory state in these patients, reflected by increased arterial wall and cellular inflammation. Statin treatment decreases cardiovascular risk and arterial inflammation in non-CKD subjects. In patients with declining kidney function, cardiovascular benefit resulting from statin therapy is attenuated, possibly due to persisting inflammation. In the current study, we assessed the effect of statin treatment on arterial wall and cellular inflammation. Fourteen patients with chronic kidney disease stage 3 or 4, defined by an estimated Glomerular Filtration Rate between 15 and 60 mL/min/1.73 m2, without cardiovascular disease were included in a single center, open label study to assess the effect of atorvastatin 40 mg once daily for 12 weeks (NTR6896). At baseline and at 12 weeks of treatment, we assessed arterial wall inflammation by 18F-fluoro-deoxyglucose positron-emission tomography computed tomography (18F-FDG PET/CT) and the phenotype of circulating monocytes were assessed. Treatment with atorvastatin resulted in a 46% reduction in LDL-cholesterol, but this was not accompanied by an attenuation in arterial wall inflammation in the aorta or carotid arteries, nor with changes in chemokine receptor expression of circulating monocytes. Statin treatment does not abolish arterial wall or cellular inflammation in subjects with mild to moderate chronic kidney disease. These results imply that CKD-associated inflammatory activity is mediated by factors beyond LDL-cholesterol and specific anti-inflammatory interventions might be necessary to further dampen the inflammatory driven CV risk in these subjects.

Treatment with Statins Does Not Revert Trained Immunity in Patients with Familial Hypercholesterolemia.

Individuals with elevated LDL-cholesterol levels have an increased risk for cardiovascular disease. Despite lipid lowering strategies, however, a significant cardiovascular risk remains. Bekkering et al. show that monocytes from patients with familial hypercholesterolemia have a trained immunity phenotype and that lipid lowering with statins does not revert this pro-inflammatory phenotype.

Elevated lipoprotein(a) levels are associated with coronary artery calcium scores in asymptomatic individuals with a family history of premature atherosclerotic cardiovascular disease.

BACKGROUND: Elevated lipoprotein(a) (Lp(a)) levels are associated with increased risk for atherosclerotic cardiovascular disease (ASCVD). Individuals with a family history of premature ASCVD are at increased cardiovascular risk with concomitantly a higher burden of (subclinical) atherosclerosis. However, whether Lp(a) contributes to the increased atherosclerotic burden in these individuals remains to be established. OBJECTIVE: In this study, we evaluated the association between Lp(a) levels and coronary atherosclerotic burden, assessed by coronary arterty calcium (CAC) scores, in asymptomatic individuals with a family history of premature ASCVD. METHODS: Lp(a) levels and other ASCVD risk factors were assessed in 432 individuals with premature ASCVD and in 937 healthy asymptomatic family members. CAC scores were only measured in asymptomatic family members. RESULTS: In this cohort, 16% had elevated Lp(a) levels, defined as ≥ 50 mg/dL. Among healthy family members, elevated Lp(a) levels were associated with both absolute CAC scores of ≥ 100 (odds ratio [OR] 1.79 [95% confidence interval {CI} 1.13-2.83]) as well as with age- and gender-corrected CAC scores ≥ 80th percentile (OR 1.69 [95% CI 1.14-2.50]). This coincides with a higher prevalence of cardiovascular events (OR 1.48 [95% CI 1.11-2.01]) in the whole cohort. CONCLUSION: Elevated Lp(a) levels were associated with higher CAC scores, both absolute as well as age- and gender-corrected percentiles, in individuals with a family history of premature ASCVD. These data imply that Lp(a) accelerates progression of atherosclerosis in these individuals, thereby contributing to their increased ASCVD risk.

CCR2 expression on circulating monocytes is associated with arterial wall inflammation assessed by 18F-FDG PET/CT in patients at risk for cardiovascular disease.

AIMS: Circulating monocytes infiltrate the plaque and differentiate into macrophages, contributing to an inflammatory environment which is associated with higher risk of cardiovascular events. Although the pivotal role of circulating monocytes in plaque inflammation has been firmly established, the search continues to identify specific monocyte subsets that may be especially atherogenic. Therefore, we evaluated the relation between monocyte phenotype, particularly surface receptor expression, and arterial wall inflammation in patients at increased cardiovascular risk. METHODS AND RESULTS: We performed a multivariate linear regression analysis in 79 patients at increased cardiovascular risk who had both an 18F-fluorodeoxyglucose positron emission tomography/computed tomography to assess arterial wall inflammation and extensive monocyte characterization (using flow cytometry). We found that CCR2, a monocyte chemokine receptor essential for transmigration, significantly correlates with arterial wall inflammation. This relationship was independent of traditional cardiovascular risk factors and statin use (ß = 0.429, P = 0.015). We found no relation between arterial wall inflammation and monocyte count or monocyte subsets, namely CD14+CD16-, CD14+CD16+, CD14+CD16 ++, CCR5+, CD18+, CD11b+, or CD11c+ monocytes. CONCLUSION: Monocyte CCR2 expression is associated with arterial wall inflammation in patients at increased cardiovascular risk. Our data warrant further studies to assess if inhibition of CCR2 may attenuate atherosclerotic plaque inflammation.

Thresholds for Arterial Wall Inflammation Quantified by 18F-FDG PET Imaging: Implications for Vascular Interventional Studies.

OBJECTIVES: This study assessed 5 frequently applied arterial 18fluorodeoxyglucose (18F-FDG) uptake metrics in healthy control subjects, those with risk factors and patients with cardiovascular disease (CVD), to derive uptake thresholds in each subject group. Additionally, we tested the reproducibility of these measures and produced recommended sample sizes for interventional drug studies. BACKGROUND: 18F-FDG positron emission tomography (PET) can identify plaque inflammation as a surrogate endpoint for vascular interventional drug trials. However, an overview of 18F-FDG uptake metrics, threshold values, and reproducibility in healthy compared with diseased subjects is not available. METHODS: 18F-FDG PET/CT of the carotid arteries and ascending aorta was performed in 83 subjects (61 ± 8 years) comprising 3 groups: 25 healthy controls, 23 patients at increased CVD risk, and 35 patients with known CVD. We quantified 18F-FDG uptake across the whole artery, the most-diseased segment, and within all active segments over several pre-defined cutoffs. We report these data with and without background corrections. Finally, we determined measurement reproducibility and recommended sample sizes for future drug studies based on these results. RESULTS: All 18F-FDG uptake metrics were significantly different between healthy and diseased subjects for both the carotids and aorta. Thresholds of physiological 18F-FDG uptake were derived from healthy controls using the 90th percentile of their target to background ratio (TBR) value (TBRmax); whole artery TBRmax is 1.84 for the carotids and 2.68 in the aorta. These were exceeded by >52% of risk factor patients and >67% of CVD patients. Reproducibility was excellent in all study groups (intraclass correlation coefficient >0.95). Using carotid TBRmax as a primary endpoint resulted in sample size estimates approximately 20% lower than aorta. CONCLUSIONS: We report thresholds for physiological 18F-FDG uptake in the arterial wall in healthy subjects, which are exceeded by the majority of CVD patients. This remains true, independent of readout vessel, signal quantification method, or the use of background correction. We also confirm the high reproducibility of 18F-FDG PET measures of inflammation. Nevertheless, because of overlap between subject categories and the relatively small population studied, these data have limited generalizability until substantiated in larger, prospective event-driven studies. (Vascular Inflammation in Patients at Risk for Atherosclerotic Disease; NTR5006).