Hypertriglyceridaemia: Management and Cardiovascular Risk

Definition and pathophysiology

Hypertriglyceridaemia (HTG) is defined by an increased concentration of circulating triglycerides. Both fasting and non-fasting measurements provide prognostic information regarding cardiovascular risk.

Thresholds vary among guideline systems:

Triglyceride-rich lipoproteins, remnant lipoproteins and insulin resistance are associated with atherosclerotic cardiovascular disease (ASCVD), particularly in peripheral arterial disease. The relationship between triglyceride concentrations and aortic disease is less clearly defined, although triglycerides may contribute to the development and progression of aortic pathology.

Severe HTG, especially when associated with chylomicronaemia, has a well-established observational association with acute pancreatitis. No clinical trial has definitively established that pharmacological triglyceride reduction prevents pancreatitis; nevertheless, treatment is generally considered appropriate when triglycerides exceed 500 mg/dL to reduce this risk. The ASCVD implications of chylomicronaemia itself remain uncertain, whereas moderate HTG, approximately 150–500 mg/dL, is associated with increased ASCVD risk. Management in this range therefore focuses principally on ASCVD prevention and reduction of LDL-C, non-HDL-C and apolipoprotein B.

Causes and secondary contributors

A search for secondary contributors is an essential first step. Recognised causes include:

• Diabetes and insulin resistance

• Thyroid disease

• Kidney disease

• Excessive alcohol consumption

• Diets high in carbohydrate or fat

• Glucocorticoids

• Beta-blockers

• Oestrogen therapy

• Some antiretroviral therapies

• Post-transplant medications, including corticosteroids, cyclosporine and sirolimus

In transplantation, corticosteroids can promote insulin resistance, free-fatty-acid synthesis and very-low-density lipoprotein production. Cyclosporine raises LDL cholesterol, partly by reducing LDL-receptor availability. Tacrolimus appears to have less adverse effect on lipids. Sirolimus may cause particularly prominent triglyceride elevation, including dose-related increases.

In people living with HIV, antiretroviral therapy may contribute to HTG. Reducing alcohol and carbohydrate intake, and considering a switch to antiretroviral agents with less adverse lipid effects, may improve triglyceride concentrations, provided viral suppression is maintained. A change in antiretroviral therapy is not recommended in individuals with previous virological failure if it risks loss of suppression.

Clinical presentation and symptoms

The source material does not describe specific symptoms or physical manifestations of HTG. Moderate HTG is primarily discussed as a cardiovascular-risk marker, while severe HTG is clinically important because of its association with acute pancreatitis.

Evaluation and physical examination

Evaluation should establish:

• The triglyceride concentration and whether the sample was fasting or non-fasting.

• The presence of ASCVD, peripheral arterial disease or aortic disease.

• Secondary causes, particularly diabetes, thyroid disease, kidney disease, alcohol excess, dietary factors and relevant medications.

• Cardiovascular risk category and the adequacy of LDL-C-lowering treatment.

• In severe primary HTG, whether specialist lipid assessment is required.

A comprehensive cardiovascular assessment should include review of modifiable risk factors and associated disease. The supplied material does not specify a diagnostic physical-examination protocol or characteristic examination findings.

Diagnostics and laboratory findings

Lipid assessment

Triglyceride concentrations should be interpreted in conjunction with LDL-C, non-HDL-C and apolipoprotein B, particularly in moderate HTG, where treatment priorities are directed toward ASCVD risk reduction and atherogenic lipoprotein lowering.

Both fasting and non-fasting triglyceride results are informative. Persistently elevated values should prompt assessment for secondary causes and review of adherence to lifestyle and lipid-lowering treatment.

Associated laboratory evaluation

The source material identifies diabetes, thyroid disease and kidney disease as important secondary contributors, but does not prescribe a specific laboratory panel. It also identifies creatine phosphokinase and hepatic-enzyme monitoring as appropriate when a statin is combined with a fibrate in people receiving antiretroviral therapy.

Cardiovascular risk associated with hypertriglyceridaemia

Triglycerides above 1.7 mmol/L (150 mg/dL) are associated with increased cardiovascular risk. Pharmacological triglyceride-lowering treatment, however, is generally reserved for high-risk patients with concentrations above 2.3 mmol/L (200 mg/dL) that remain elevated despite lifestyle intervention.

The evidence for fibrates in cardiovascular prevention is limited. In peripheral arterial disease, fibrates did not demonstrate benefit over placebo for major adverse cardiovascular events or for coronary and cerebrovascular outcomes. Routine use of fibrates solely for cardiovascular prevention is therefore not recommended in the supplied guidance.

Icosapent ethyl has demonstrated reductions in cardiovascular morbidity and mortality in patients with HTG, although its specific impact in peripheral arterial and aortic disease remains unexplored.

Management principles

Lifestyle and dietary intervention

All patients with HTG should receive intensive lifestyle and dietary advice. Core measures include:

• Reduction of excessive alcohol intake

• Reduction of dietary carbohydrate and fat excess

• Optimization of body weight

• Regular physical activity

• Improved glycaemic control when diabetes or insulin resistance is present

• Correction of other modifiable cardiovascular risk factors

In people living with HIV, caloric restriction and exercise should be used to approach ideal body weight. Resistance training has been associated with lower fasting triglycerides and adipose-tissue mass, together with increased muscle mass, although lifestyle measures alone frequently do not achieve adequate lipid control.

Treatment of secondary causes

Secondary contributors should be actively identified and treated. This includes:

• Improving diabetes control

• Addressing thyroid disease

• Managing kidney disease

• Reviewing glucocorticoids, beta-blockers, oestrogen therapy and other potentially contributory drugs

• Reducing alcohol consumption

• Reviewing the carbohydrate and fat content of the diet

• Considering modification of antiretroviral or transplant therapy where clinically safe

LDL-C-focused treatment

Statin treatment should be optimized in patients with HTG. In moderate HTG, reduction of LDL-C, non-HDL-C and apolipoprotein B remains central to ASCVD prevention.

Fibrates are primarily triglyceride-lowering drugs and may increase HDL-C, but routine use for cardiovascular-event prevention is not supported by the available evidence. In severe HTG, a fibrate or omega-3 fatty acid preparation may be added to lifestyle measures and optimized statin therapy.

Severe hypertriglyceridaemia

When triglycerides exceed 500 mg/dL, intervention is generally considered appropriate to reduce pancreatitis risk. Management includes dietary modification, alcohol avoidance, treatment of diabetes and optimization of statin therapy. Fibrates or omega-3 fatty acids may be added.

When triglycerides exceed 10 mmol/L (900 mg/dL), triglycerides should be reduced through combined measures, including pharmacological therapy, alcohol restriction, diabetes treatment and withdrawal of oestrogen therapy where relevant. Severe primary HTG warrants consideration of referral to a lipid specialist.

Pharmacological treatment

Statins

Statins are the principal pharmacological treatment for ASCVD risk reduction in patients with HTG. Therapy should be optimized before considering additional triglyceride-directed treatment.

In people living with HIV, statin selection must account for antiretroviral interactions:

• Pravastatin and fluvastatin have fewer interaction concerns but are less potent for LDL-C reduction.

• Rosuvastatin and atorvastatin are appropriate when high-intensity LDL-C reduction is required, but dose adjustment may be necessary.

• With ritonavir-boosted protease inhibitors such as atazanavir or lopinavir, atorvastatin should not exceed 40 mg/day and rosuvastatin should not exceed 10 mg/day.

• Lovastatin and simvastatin are contraindicated with protease inhibitors and efavirenz because of the risk of excessive statin exposure and rhabdomyolysis.

• Pitavastatin has limited drug–drug interaction potential because it undergoes glucuronidation. In a cardiovascular-outcomes trial involving people with HIV, pitavastatin was administered at 4 mg/day.

• Ezetimibe is an option for statin-intolerant patients and may be added in very-high-risk patients who do not achieve adequate LDL-C reduction.

• Bempedoic acid is another option in statin intolerance; the supplied material reports a 21% greater LDL-C reduction than placebo and a 13% reduction in major adverse cardiovascular events in a population without HIV.

• Bile-acid sequestrants are not recommended in HIV because they may increase triglycerides and their effects on antiretroviral-drug absorption have not been adequately studied.

• PCSK9 inhibitors can provide substantial LDL-C reduction while avoiding statin-related drug interactions. In a randomized trial involving people with HIV, evolocumab reduced LDL-C by 57% over 24 weeks; LDL-C below 70 mg/dL was achieved in 73% of patients receiving evolocumab compared with 8% receiving placebo.

Icosapent ethyl

Icosapent ethyl is a purified eicosapentaenoic-acid ethyl ester. It may be considered with statin treatment in high-risk or very-high-risk patients whose fasting triglycerides remain between 135 and 499 mg/dL (1.52–5.63 mmol/L).

The guideline recommendation is:

Other guidance describes an icosapent ethyl dose of 2–4 g/day. In the cardiovascular-outcomes trial cited in the source material, the regimen was 2 g twice daily as add-on therapy to statins.

In patients with HIV, omega-3 fatty acids generally lack important drug interactions, although some fish-oil preparations may modestly increase LDL-C. Icosapent ethyl has demonstrated cardiovascular benefit in people with cardiovascular disease or diabetes and other cardiovascular risk factors with fasting triglycerides of 150–499 mg/dL.

Fibrates

Fibrates lower triglycerides and may increase HDL-C, but their evidence for reducing cardiovascular events is limited. They are not recommended routinely for cardiovascular prevention and showed no benefit over placebo in the peripheral arterial disease evidence summarized in the source material.

They may nevertheless be considered in severe HTG, particularly when the treatment objective is triglyceride reduction and pancreatitis-risk mitigation. In people with HIV, fibrates can interact with statins and some antiretroviral therapies. For patients receiving a statin, fibrate and antiretroviral therapy, hepatic enzymes and creatine phosphokinase should be monitored.

Omega-3 fatty acids

Omega-3 fatty acids may be added in severe HTG. In patients with HIV, fish-oil preparations lower triglycerides and generally have few important drug interactions, although some preparations can modestly increase LDL-C.

Volanesorsen

Volanesorsen may be considered in familial chylomicronaemia syndrome with severe HTG:

Other agents

PCSK9 inhibitors are principally LDL-C-lowering agents rather than standard triglyceride-directed therapy. The supplied material lists them among available pharmacological interventions for triglyceride management but does not provide a specific triglyceride indication or dose.

Lipid-lowering nutraceuticals may assist treatment adherence or LDL-C goal attainment in practice, but no outcome studies are cited as demonstrating prevention of cardiovascular morbidity or mortality.

Special clinical settings

Diabetes and coronary artery disease

Patients with diabetes and established coronary artery disease require comprehensive risk-factor management, including lifestyle intervention and treatment of obesity, hypertension and dyslipidaemia. In patients with type 2 diabetes and coronary artery disease, SGLT2 inhibitors and/or GLP-1 receptor agonists are recommended to reduce cardiovascular events.

Chronic kidney disease and diabetes

Patients with diabetes and chronic kidney disease have progressively increasing cardiovascular risk as estimated glomerular filtration rate declines. Statin-based therapy reduces major atherosclerotic events, although it does not meaningfully slow chronic kidney disease progression.

The goal is to achieve the greatest safely attainable absolute LDL-C reduction. Intensive LDL-C lowering with statins, alone or with ezetimibe, has been shown to be safe in the CKD populations described. Evolocumab retains its LDL-C-lowering effect in stage G3 CKD, with cardiovascular benefits appearing unmodified by baseline estimated glomerular filtration rate.

Heart failure

Low cholesterol levels in heart failure are associated with increased mortality. Initiation of lipid-lowering treatment is not recommended in heart failure without a compelling indication. This principle is distinct from treatment of established ASCVD or another clear indication for lipid-lowering therapy.

Heart transplantation

After transplantation, total cholesterol, LDL cholesterol and triglycerides commonly increase by approximately three months, followed by some decline during the subsequent year. Corticosteroids, cyclosporine, sirolimus and other transplant medications may contribute.

Statins remain the mainstay of treatment and should be administered irrespective of LDL levels in heart-transplant recipients. The source material associates statin treatment with improved one-year survival and describes benefits associated with pravastatin and simvastatin in survival, rejection severity and cardiac allograft vasculopathy. PCSK9 inhibitors have been reported as safe and effective for LDL lowering, although outcome studies are still required.

Guideline-based treatment thresholds

A practical synthesis of the supplied recommendations is shown below:

Prognosis and follow-up

Moderate HTG is associated with increased ASCVD risk, whereas severe HTG is associated with pancreatitis risk, particularly in the setting of chylomicronaemia. The precise effect of triglyceride lowering on pancreatitis prevention remains unproven in clinical trials, but intervention at high concentrations is considered appropriate clinical practice.

Follow-up should reassess:

• Triglyceride, LDL-C, non-HDL-C and, where used, apolipoprotein B concentrations

• Adherence to dietary and lifestyle measures

• Alcohol intake

• Glycaemic control

• Thyroid and kidney disease

• Medication-related secondary causes

• Drug–drug interactions

• Hepatic enzymes and creatine phosphokinase when statin–fibrate combinations are used with antiretroviral therapy

• Evidence of ASCVD progression or pancreatitis

In patients with persistent severe or primary HTG, specialist lipid assessment should be considered. In transplant recipients and patients receiving complex therapies, lipid management should be integrated with surveillance for cardiovascular complications and coordinated among the relevant specialist teams.