Hanna E. Bloomfield

Low-Density Lipoprotein and High-Density Lipoprotein Particle Subclasses Predict Coronary Events and Are Favorably Changed by Gemfibrozil Therapy in the Veterans Affairs High-Density Lipoprotein Intervention Trial

Background— Changes in conventional lipid risk factors with gemfibrozil treatment only partially explain the reductions in coronary heart disease (CHD) events experienced by men in the Veterans Affairs High-Density Lipoprotein Intervention Trial (VA-HIT). We examined whether measurement of low-density lipoprotein (LDL) and high-density lipoprotein (HDL) particle subclasses provides additional information relative to CHD risk reduction. Methods and Results— This is a prospective nested case-control study of 364 men with a new CHD event (nonfatal myocardial infarction or cardiac death) during a 5.1-year (median) follow-up and 697 age-matched controls. Nuclear magnetic resonance (NMR) spectroscopy was used to quantify levels of LDL and HDL particle subclasses and mean particle sizes in plasma obtained at baseline and after 7 months of treatment with gemfibrozil or placebo. Odds ratios for a 1-SD increment of each lipoprotein variable were calculated with adjusted logistic regression models. Gemfibrozil treatment increased LDL size and lowered numbers of LDL particles (−5%) while raising numbers of HDL particles (10%) and small HDL subclass particles (21%). Concentrations of these LDL and HDL particles achieved with gemfibrozil were significant, independent predictors of new CHD events. For total LDL and HDL particles, odds ratios predicting CHD benefit were 1.28 (95% CI, 1.12 to 1.47) and 0.71 (95% CI, 0.61 to 0.81), respectively. Mean LDL and HDL particle sizes were not associated with CHD events. Conclusions— The effects of gemfibrozil on NMR-measured LDL and HDL particle subclasses, which are not reflected by conventional lipoprotein cholesterol measures, help to explain the demonstrated benefit of this therapy in patients with low HDL cholesterol.

Value of High-Density Lipoprotein (HDL) Subpopulations in Predicting Recurrent Cardiovascular Events in the Veterans Affairs HDL Intervention Trial

Objective—To test the hypothesis whether determination of high-density lipoprotein (HDL) subpopulations provides more power to predict recurrent cardiovascular disease (CVD) events (nonfatal myocardial infarction, coronary heart disease death, and stroke) than traditional risk factors in the Veterans Affairs HDL Intervention Trial (VA-HIT). Methods and Results—Apolipoprotein A-I (apoA-I)–containing HDL subpopulations were quantitatively determined by nondenaturing 2D gel electrophoresis. Hazard ratios of recurrent CVD events were calculated by comparing VA-HIT subjects with (n=398) and without (n=1097) such events. Subjects with new CVD events had significantly lower HDL-C, apoA-I, and large cholesterol-rich HDL particle (α-1, α-2, pre–α-1, and pre–α-2) levels, significantly higher triglyceride, and small poorly lipidated HDL particle (pre–β-1 and α-3) levels than subjects without such events. Multivariate analyses indicated that α-1 and α-2 particle levels were significant negative risk factors, whereas α-3 level was a significant positive risk factor for new CVD events. Pre–β-1 level was a significant risk factor for new CVD events only in univariate analysis. A forward selection model indicated that α-1 was the most significant risk factor for recurrent CVD events among HDL particles. Conclusions—An altered HDL subpopulation profile marked with low α-1 and α-2 levels and a high α-3 level in coronary heart disease patients indicated an elevated risk for new CVD events. Moreover, α-1 and α-2 levels were superior to HDL-C levels in risk assessment in patients with low HDL-C in VA-HIT.

Cardiovascular events with increased lipoprotein-associated phospholipase A 2 and low high-density lipoprotein-cholesterol the veterans affairs HDL intervention trial

Objective—Lipoprotein-associated phospholipase A2 (Lp-PLA2), a proinflammatory enzyme that predominantly circulates with low-density lipoprotein (LDL), has been shown in general populations to predict cardiovascular (CV) events. We sought to determine whether increased Lp-PLA2 would also predict CV events in the absence of high LDL-cholesterol (LDL-C), in a population with low high-density lipoprotein-cholesterol (HDL-C). Methods and Results—Plasma Lp-PLA2 activity was measured at baseline and after 6 months on-trial in 1451 men with low HDL-C (mean, 32 mg/dL) and low LDL-C (mean 110 mg/dL), randomized to either placebo or gemfibrozil therapy in the Veterans Affairs HDL Intervention Trial (VA-HIT). Over a quartile range of increasing Lp-PLA2 there was a significant increase in LDL-C and decrease in HDL-C (P<0.0001), and an increased percentage of myocardial infarction (MI), stroke, or CHD death (P=0.03 for trend). In Cox models, adjusted for major CV risk factors, a 1-SD increase in Lp-PLA2 was associated with a significant increase in CV events (hazard ratio [HR] 1.17 95% CI 1.04 to 1.32). Although gemfibrozil reduced Lp-PLA2 only modestly (6.6%), at higher levels of Lp-PLA2 gemfibrozil produced a significant reduction in CV events. Conclusions—In VA-HIT, a population with low HDL-C and LDL-C, high Lp-PLA2 independently predicted CV events that were reduced by gemfibrozil.

Fibric acid derivatives in cardiovascular disease prevention: results from the large clinical trials.

Purpose of review Results from five large placebo-controlled trials with second-generation fibrates have shown varying success in reducing cardiovascular events. This review focuses on a number of extended analyses from these trials that may relate to the success or failure of fibrate therapy and indicate who might likely benefit from this therapy. Recent findings Results have been far from uniform and several trials have been adversely impacted by high off-trial statin use. Collective evidence suggests, however, that fibrates have optimum cardiovascular benefit in diabetes or other manifestations of insulin resistance. Much of this evidence comes from posttrial analysis in subgroups with more sharply defined clinical characteristics than in the overall trial population. Analyses also suggest that different fibrates have a different range of favorable clinical properties, that the cardiovascular benefit of fibrates may not be readily measured or mostly predicted by changes in traditional lipid measurements, and that other nonlipid properties of fibrates as peroxisome proliferator-activated receptor agents might explain some of the benefit of these drugs. Summary Results of major clinical endpoint trials with fibrates, although not uniformly positive, provide substantial evidence for a selective therapeutic role of these drugs in cardiovascular event reduction in diabetes or insulin resistance.

Polymorphisms in the gene encoding lipoprotein lipase in men with low HDL-C and coronary heart disease: the Veterans Affairs HDL Intervention Trial.

Our goal was to further define the role of LPL gene polymorphisms in coronary heart disease (CHD) risk. We determined the frequencies of three LPL polymorphisms (D9N, N291S, and S447X) in 899 men from the Veterans Affairs HDL Intervention Trial (VA-HIT), a study that examined the potential benefits of increasing HDL with gemfibrozil in men with established CHD and low high density lipoprotein cholesterol (HDL-C; ⩽40 mg/dl), and compared them with those of men without CHD from the Framingham Offspring Study (FOS). In VA-HIT, genotype frequencies for LPL D9N, N291S, and S447X were 5.3, 4.5, and 13.0%, respectively. These values differed from those for men in FOS having an HDL-C of >40, who had corresponding values of 3.2% (P = 0.06), 1.5% (P < 0.01), and 18.2% (P < 0.01). On gemfibrozil, carriers of the LPL N9 allele in VA-HIT had lower levels of large LDL (−32%; P < 0.01) but higher levels of small, dense LDL (+59%; P < 0.003) than did noncarriers. Consequently, mean LDL particle diameter was smaller in LPL N9 carriers than in noncarriers (20.14 ± 0.87 vs. 20.63 ± 0.80 nm; P < 0.003). In men with low HDL-C and CHD: 1) the LPL N9 and S291 alleles are more frequent than in CHD-free men with normal HDL-C, whereas the X447 allele is less frequent, and 2) the LPL N9 allele is associated with the LDL subclass response to gemfibrozil.