Did the ACC/AHA/AACVPR/AAPA/ABC/ACPM/ADA/AGS/APhA/ASPC/NLA/PCNA cholesterol guidelines get apoB right?

Saturated fat and CVD: importance of inter-individual variation in the response of serum low-density lipoprotein cholesterol

The aim of this review is to provide an overview of the history in support of the role of dietary saturated fatty acids (SFA) in the development of cardiovascular disease (CVD), and the controversy and consensus for the evidence in support of guidelines to remove and replace SFA with unsaturated fatty acids. The review will also examine the existence, origins, and implications for CVD risk of variability in serum LDL-cholesterol in response to these guidelines. While the quality of supporting evidence for the efficacy of restricting SFA on CVD risk has attracted controversy, this has helped to increase understanding of the inter-relationships between SFA, LDL-cholesterol and CVD, and reinforce confidence in this dietary recommendation. Nevertheless, there is significant inter-individual variation in serum LDL-C in response to this dietary change. The origins of this variation are multi-factorial and involve both dietary and metabolic traits. If serum biomarkers of more complex metabolic traits underlying LDL-responsiveness can be identified, this would have major implications for the targeting of these dietary guidelines to LDL-responders, to maximise the benefit to their cardiovascular health.

What should be the goal of cholesterol-lowering treatment? A quantitative evaluation dispelling guideline myths

PURPOSE OF REVIEW

Guidelines for cholesterol-lowering treatment generally include extensive review of epidemiological and clinical trial evidence. However, the next logical step, the translation of evidence into clinical advice, occurs not entirely by reasoning, but by a form of consensus in which the prejudices and established beliefs of the societies with interests in cardiovascular disease convened to interpret the evidence are prominent. Methods, which are the subject of this review, have, however, been developed by which clinical trial evidence can be translated objectively into best practice.

RECENT FINDINGS

Guidelines differ in their recommended goals for cholesterol-lowering treatment in the prevention of atherosclerotic cardiovascular disease (ASCVD). Proposed goals are LDL-cholesterol 2.6 mmol/l (100 mg/dl) or less in lower risk, LDL-cholesterol 1.8 mmol/l (70 mg/dl) or less in higher risk, non-HDL-cholesterol decrease of at least 40% or LDL-cholesterol 1.8 mmol/l (70 mg/dl) or less or decreased by at least 50% whichever is lower. Evidence from clinical trials of statins, ezetimibe and proprotein convertase subtilisin/kexin type 9-inhibitors can be expressed in simple mathematical terms to compare the efficacy on ASCVD incidence of clinical guidance for the use of cholesterol-lowering medication. The target LDL-cholesterol of 2.6 mmol/l (100 mg/dl) is ineffective and lacks credibility. Cholesterol-lowering medication is most effective in high-risk people with raised LDL-cholesterol. The best overall therapeutic target is LDL-cholesterol 1.8 mmol/l (70 mg/dl) or less or decreased by at least 50% whichever is lower. The use of non-HDL-cholesterol as a therapeutic goal is less efficacious. Aiming for LDL-cholesterol 1.4 mmol/l (55 mg/dl) or less as opposed to 1.8 mmol/l produces only a small additional benefit. Evidence for apolipoprotein B targets in hypertriglyceridaemia and in very high ASCVD risk should be more prominent in future guidelines.

SUMMARY

The LDL-cholesterol goal of 2.6 mmol/l or less should be abandoned. Percentage decreases in LDL-cholesterol or non-HDL-cholesterol concentration are better in people with initial concentrations of less than 3.6 mmol/l. The LDL-cholesterol target of 1.8 mmol/l is most effective when initial LDL-cholesterol is more than 3.6 mmol/l in both primary and secondary prevention.

Obesity and BMI Cut Points for Associated Comorbidities: Electronic Health Record Study

Background

Studies have found associations between increasing BMIs and the development of various chronic health conditions. The BMI cut points, or thresholds beyond which comorbidity incidence can be accurately detected, are unknown.

Objective

The aim of this study is to identify whether BMI cut points exist for 11 obesity-related comorbidities.

Methods

US adults aged 18-75 years who had ≥3 health care visits at an academic medical center from 2008 to 2016 were identified from eHealth records. Pregnant patients, patients with cancer, and patients who had undergone bariatric surgery were excluded. Quantile regression, with BMI as the outcome, was used to evaluate the associations between BMI and disease incidence. A comorbidity was determined to have a cut point if the area under the receiver operating curve was >0.6. The cut point was defined as the BMI value that maximized the Youden index.

Results

We included 243,332 patients in the study cohort. The mean age and BMI were 46.8 (SD 15.3) years and 29.1 kg/m², respectively. We found statistically significant associations between increasing BMIs and the incidence of all comorbidities except anxiety and cerebrovascular disease. Cut points were identified for hyperlipidemia (27.1 kg/m²), coronary artery disease (27.7 kg/m²), hypertension (28.4 kg/m²), osteoarthritis (28.7 kg/m²), obstructive sleep apnea (30.1 kg/m²), and type 2 diabetes (30.9 kg/m²).

Conclusions

The BMI cut points that accurately predicted the risks of developing 6 obesity-related comorbidities occurred when patients were overweight or barely met the criteria for class 1 obesity. Further studies using national, longitudinal data are needed to determine whether screening guidelines for appropriate comorbidities may need to be revised.

Does variation in serum LDL-cholesterol response to dietary fatty acids help explain the controversy over fat quality and cardiovascular disease risk?

Controversy over fat quality and cardiovascular disease risk stems from a series of meta-analyses of prospective cohort and randomised intervention trials, which found little evidence for a significant relationship between the intake of saturated fat and disease endpoints. Possible explanations for these null findings include difficulties inherent in estimating true food intake, the confounding effects of macronutrient replacement and food composition, and marked inter-individual variation in the response of serum LDL-cholesterol. The aim of this narrative review was to present evidence for the existence and origins of variation in serum LDL-cholesterol response to the replacement of dietary saturated fat, and its potential to explain the controversy over the latter. The review provides evidence to suggest that variation in LDL-responsiveness may harbour significant potential to confound the relationship between saturated fat and atherosclerotic cardiovascular disease risk, thus undermining the effectiveness of the dietary guideline to replace saturated fat with unsaturated fat. It concludes that the identification and application of a simple biomarker of this phenomenon, would make it possible to tailor dietary guidelines to LDL responsive individuals, who stand to gain a greater benefit to their cardiovascular health.

Relative effect of hypertriglyceridemia on non-HDLC and apolipoprotein B as cardiovascular disease risk markers

BACKGROUND

Non-high density lipoprotein cholesterol (non-HDLC) represents the cholesterol in triglyceride-rich lipoproteins (TRL) and low-density lipoproteins (LDL). Apolipoprotein B (apoB) reflects the number of TRL and LDL particles. In hypertriglyceridemia (HTG), there is triglyceride (TG) enrichment of TRLs, and also a substantial increase of cholesterol in larger TRLs that considerably augments the non-HDLC value. Therefore, in HTG, non-HDLC could increase disproportionately with respect to apoB.

OBJECTIVE

We aimed to compare the relative effect of the full range of mild, moderate, and severe HTG on the status of non-HDLC and apoB as cardiovascular disease (CVD) risk markers.

METHODS

Analysis of lipid profile data from 4347 patients in a Lipid Clinic cohort with baseline fasting lipid profiles documented prior to starting lipid-lowering medications. The correlation between non-HDLC and apoB was assessed in intervals of increasing TG. Non-HDLC and apoB were analyzed at each TG level using comparative CVD risk equivalent categories and assessed for divergence and discordance.

RESULTS

With increasing TG levels: (1) the correlation between non-HDLC and apoB diminished progressively, (2) non-HDLC levels increased continuously, whereas apoB levels plateaued after an initial increase up to TG of ~ 4.0-5.0 mmol/L (~354-443 mg/dL), (3) there was divergence in the stratification of non-HDLC and apoB into CVD risk equivalent categories.

CONCLUSIONS

Non-HDLC and apoB should not be viewed as interchangeable CVD risk markers in the presence of severe HTG. This has never been tested. With increasing HTG severity, discordance between non-HDLC and apoB can cause clinically important divergence in CVD risk categorization.

Triglycerides and residual risk

PURPOSE OF REVIEW

To review the recent evidence from observational/genetic/interventional studies addressing triglycerides and residual cardiovascular risk (CVRisk).

RECENT FINDINGS

Large population-based and secondary prevention studies consistently show an association of higher triglycerides with increased CVRisk. This is compounded by genetic studies demonstrating an independent relationship between triglyceride raising or lowering genetic variants affecting triglyceride-rich lipoproteins (TRL) metabolism and CVRisk. Mendelian randomization analysis suggests the benefit of genetic lowering of triglycerides and LDL-cholesterol is similar per unit change in apolipoprotein-B. Among cholesterol-lowering trials, more intensive statin therapy produced greater CVRisk reductions in patients with higher TRL-cholesterol or triglycerides; proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibition led to similar triglycerides reduction but greater non-HDL-C or apolipoprotein-B reductions than fibrates or fish oils. Regarding n-3 fatty acids, A Study of Cardiovascular Events in Diabetes (ASCEND) and Vitamin D and Omega-3 Trial (VITAL) primary prevention trials with eicosapentaenoic acid (EPA) and docosahexaenoic acid failed to demonstrate cardiovascular benefits, Conversely, Reduction of Cardiovascular Events with Icosapent Ethyl-Intervention Trial (REDUCE-IT) using high-dose icosapent-ethyl (purified EPA) in primary (diabetes) and secondary prevention with hypertriglyceridemia showed significant cardiovascular events reductions (greater than expected by the observed triglycerides or apolipoprotein-B reductions, suggesting potential benefits through non-lipid pathways).

SUMMARY

Evidence suggests higher triglycerides are a marker of CVRisk and may help identify patients who benefit from intensification of therapy. Moreover, genetic studies support a causal link between TRL/triglycerides and cardiovascular disease. Treatment with high-dose EPA may be of benefit in high-risk patients with hypertriglyceridemia to reduce CVRisk.