Clinical Trial Design for Triglyceride-Rich Lipoprotein-Lowering Therapies: JACC Focus Seminar 3/3

Triglyceride to high-density lipoprotein cholesterol ratio associated with long-term adverse clinical outcomes in patients deferred revascularization following fractional flow reserve

BACKGROUND

Guidelines on coronary intermediate lesions strongly recommend deferred revascularization after detecting a normal fractional flow reserve (FFR). Researches about triglyceride to high-density lipoprotein cholesterol (TG/HDL-C) on cardiovascular diseases has also been well conducted. However, the association of TG/HDL-C and long-term adverse clinical outcomes remains unknown for patients deferred revascularization following FFR.

METHODS

This study retrospectively included 374 coronary artery disease (CAD) patients with non-significant coronary lesions diagnosed by coronary angiography (CAG) and FFR. The main outcome measure was the combination of major adverse cardiovascular and cerebrovascular events (MACCEs). All patients were categorized into three subgroups in terms of TG/HDL-C tertiles (T1 < 0.96, 0.96 ≤ T2 < 1.58, T3 ≥ 1.58). Three different Cox regression models were utilized to reveal the association between TG/HDL-C and prevalence of MACCEs.

RESULTS

47 MACCEs were recorded throughout a median monitoring period of 6.6 years. The Kaplan-Meier survival curves showed a higher MACCEs rate occurred in the higher TG/HDL-C group (5.6% vs. 12.9% vs. 19.4%, log-rank P < 0.01). After adjustment, patients in T3 suffered a 2.6-fold risk compared to the T1 group (T3 vs. T1: HR 2.55, 95% CI 1.05-6.21, P = 0.038; T2 vs. T1: HR 1.71, 95% CI 0.65-4.49, P = 0.075; P for trend = 0.001). The restricted cubic spline (RCS) analysis demonstrated that the HR for MACCEs rose as TG/HDL-C increased. Both the receiver operating characteristic (ROC) and time-dependent ROC proved the excellent predictive ability of TG/HDL-C.

CONCLUSION

The study illustrates that TG/HDL-C correlates with the risk of MACCEs in CAD patients deferred revascularization following FFR. TG/HDL-C could serve as a dependable predictor of cardiovascular events over the long term in this population.

Remnant cholesterol and low-grade inflammation jointly in atherosclerotic cardiovascular disease: implications for clinical trials

PURPOSE OF REVIEW

Atherosclerotic cardiovascular disease (ASCVD) is the leading cause of death despite the development of effective treatments. Recently, elevated remnant cholesterol and low-grade inflammation have emerged as factors explaining part of the residual ASCVD risk. Interestingly, the coexistence of both high remnant cholesterol and low-grade inflammation can further increase the risk of ASCVD. The aim of this review is to describe the role of elevated remnant cholesterol and low-grade inflammation, separately and combined, in ASCVD.

RECENT FINDINGS

Results from recently published studies, including observational and genetic Mendelian randomization studies, support a causal relationship between elevated remnant cholesterol and low-grade inflammation on risk of ASCVD in both primary and secondary prevention settings. In addition, current evidence from observational studies suggests that the coexistence of elevated remnant cholesterol and low-grade inflammation further increases the risk of ASCVD.

SUMMARY

Recent observational studies suggest that high remnant cholesterol combined with low-grade inflammation may confer a particular high risk for ASCVD. Attention on the dual threat from high remnant cholesterol and low-grade inflammation is necessary, and further research in this field is warranted. The effect of remnant cholesterol-lowering drugs and anti-inflammatory drugs on ASCVD risk alone and combined remains to be elucidated.

VIDEO ABSTRACT

http://links.lww.com/COCN/A20.

Apolipoprotein C3: form begets function

Increased circulating levels of apolipoprotein C3 (APOC3) predict cardiovascular disease (CVD) risk in humans, and APOC3 promotes atherosclerosis in mouse models. APOC3's mechanism of action is due in large part to its ability to slow the clearance of triglyceride-rich lipoproteins (TRLs) and their remnants when APOC3 is carried by these lipoproteins. However, different pools and forms of APOC3 exert distinct biological effects or associations with atherogenic processes. Thus, lipid-free APOC3 induces inflammasome activation in monocytes whereas lipid particle-bound APOC3 does not. APOC3-enriched LDL binds better to the vascular glycosaminoglycan biglycan than does LDL depleted of APOC3. Patterns of APOC3 glycoforms predict CVD risk differently. The function of APOC3 bound to HDL is largely unknown. There is still much to learn about the mechanisms of action of different forms and pools of APOC3 in atherosclerosis and CVD, and whether APOC3 inhibition would prevent CVD risk in patients on LDL-cholesterol lowering medications.

How to Handle Elevated Triglycerides: Life after PROMINENT

PURPOSE OF REVIEW

Hypertriglyceridaemia (HTG) is a common condition characterised by elevated levels of plasma triglycerides (TG), which are transported in the blood mainly by TG-rich lipoproteins (TRL). Elevated TG levels (150-400 mg/dL) are associated with increased cardiovascular risk. Severe HTG (>880 mg/dL) is associated with a risk of acute pancreatitis only. Randomised clinical trials investigating the clinical benefit of TG-lowering drugs in patients with elevated TG levels have provided conflicting results.

RECENT FINDINGS

Elevated TG levels are only one marker of altered lipid/lipoprotein metabolism and indeed reflect altered concentrations of one or more classes or subfractions of TRL, which in turn may have a different association with CV risk. Fibrates, the drugs most commonly used to treat HTG, provide cardiovascular benefits to only a specific subgroup of patients. The lack of clinical benefit from pemafibrate has emphasised the concept that lowering TG levels is not sufficient to reduce the CV risk unless it is accompanied by a reduction in the number of circulating atherogenic lipoproteins, which can be assessed by determining apolipoprotein B levels. Treatment with omega-3 fatty acids was also ineffective in reducing CV risk, with the exception of icosapent ethyl, which, however, appears to have beneficial effects beyond lipids. New drugs are currently being developed that aim to lower TG levels by targeting apolipoprotein C-III or angiopoietin-like-3, both of which are involved in the metabolism of TGs. TG reduction can be achieved by various drugs, but most of them are ineffective in reducing CV risk. The results of outcome studies on new TG-lowering drugs will clarify whether lowering apoB levels is critical to achieve clinical benefit.

Severe hypertriglyceridemia: Existing and emerging therapies

Severe hypertriglyceridemia (sHTG), defined as a triglyceride (TG) concentration ≥ 500 mg/dL (≥ 5.7 mmol/L) is an important risk factor for acute pancreatitis. Although lifestyle, some medications, and certain conditions such as diabetes may lead to HTG, sHTG results from a combination of major and minor genetic defects in proteins that regulate TG lipolysis. Familial chylomicronemia syndrome (FCS) is a rare disorder caused by complete loss of function in lipoprotein lipase (LPL) or LPL activating proteins due to two homozygous recessive traits or compound heterozygous traits. Multifactorial chylomicronemia syndrome (MCS) and sHTG are due to the accumulation of rare heterozygous variants and polygenic defects that predispose individuals to sHTG phenotypes. Until recently, treatment of sHTG focused on lifestyle interventions, control of secondary factors, and nonselective pharmacotherapies that had modest TG-lowering efficacy and no corresponding reductions in atherosclerotic cardiovascular disease events. Genetic discoveries have allowed for the development of novel pathway-specific therapeutics targeting LPL modulating proteins. New targets directed towards inhibition of apolipoprotein C-III (apoC-III), angiopoietin-like protein 3 (ANGPTL3), angiopoietin-like protein 4 (ANGPTL4), and fibroblast growth factor-21 (FGF21) offer far more efficacy in treating the various phenotypes of sHTG and opportunities to reduce the risk of acute pancreatitis and atherosclerotic cardiovascular disease events.

The role of atherogenic lipoproteins in diabetes: Molecular aspects and clinical significance

Dyslipidaemia plays a prominent role in the genesis of atherosclerotic plaque and the increased cardiovascular risk in diabetes. Macrophages readily take up atherogenic lipoproteins, transforming into foam cells and amplifying vascular damage in the presence of endothelial dysfunction. We discuss the importance of distinct lipoprotein subclasses in atherogenic diabetic dyslipidaemia as well as the effects of novel anti-diabetic agents on lipoprotein fractions and ultimately on cardiovascular risk prevention. In patients with diabetes, lipid abnormalities should be aggressively identified and treated in conjunction with therapeutical agents used to prevent cardiovascular disease. The use of drugs that improve diabetic dyslipidaemia plays a prominent role in conferring cardiovascular benefit in individuals with diabetes.