Residual Risk After Lipid Goal Achievement in Metabolic Syndrome
The results of an analysis presented by Robert Rosenson, MD (University of Michigan, Ann Arbor), showed that in patients with the metabolic syndrome, lowering LDL-C does not reflect similar reductions in LDL particle levels. Although lowering LDL-C improves CHD risk, LDL-C may be normal in patients with the metabolic syndrome while at the same time LDL particle levels may be increased. Thus, achieving LDL-C goals may underestimate CHD risk in these patients, whereas managing them to LDL particle goals may minimize residual risk and optimize treatment in this population.
Together with investigators from LipoScience (Raleigh, North Carolina) and AstraZeneca, Dr. Rosensen examined the effects of statins on LDL particle level and LDL-C in a secondary analysis of the COmparative study with rosuvastatin in subjects with METabolic Syndrome (COMETS), an international, multicenter clinical trial supported by AstraZeneca.
Study design. COMETS was carried out in 401 men and women aged 18 years and older with the metabolic syndrome as defined by the presence of at ≥ 3 of the following: abdominal obesity (waist circumference > 102 cm [40 inches] for men and > 88 cm [35 inches] for women); triglycerides ≥ 1.70 mmol/L (150 mg/dL); HDL-C < 1.04 mmol/L (40 mg/dL) for men and < 1.30 mmol/L (50 mg/dL) for women; blood pressure ≥ 130/85 mm Hg or receiving antihypertensive treatment; and fasting blood glucose ≥ 6.11 mmol/L (110 mg/dL). Patients were also required to have LDL-C ≥ 3.36 mmol/L (130 mg/dL) and additional multiple risk factors conferring a 10-year CHD risk score of > 10%.
Patients were randomized in a double-blind fashion to receive rosuvastatin 10 mg/day, atorvastatin 10 mg/day, or placebo from baseline to week 6. From week 6 to week 12, patients who had been on rosuvastatin 10 mg/day or placebo received rosuvastatin 20 mg/day and those previously on atorvastatin 10 mg/day took atorvastatin 20 mg/day. LDL-C was determined by beta-quantification; LDL particles were measured by nuclear magnetic resonance spectroscopy.
Study results. A significantly greater reduction in LDL-C at 6 weeks, the primary efficacy endpoint of the study, was seen in patients receiving rosuvastatin 10 mg compared with those receiving atorvastatin 10 mg (41.7% vs 35.7%, P < .001). Significant LDL-C reductions were also observed in patients receiving rosuvastatin compared with those receiving atorvastatin at 12 weeks (P < .001). More patients achieved LDL-C goals (European guidelines for 1998 and 2003 and NCEP ATP III) with rosuvastatin compared with atorvastatin. Rosuvastatin increased HDL-C by 15% compared with placebo, significantly more than atorvastatin.
Dr. Rosensen and his colleagues found differences in the effects of the statins in lowering LDL-C and lowering LDL particle concentration. In the rosuvastatin group, LDL-C decreased by 50% (from an average of 168 to 84 mg/dL) over 12 weeks, but LDL particle concentration decreased by only 38% (from an average of 1960 to 1210 nmol/L) over the same period ( Table 11 ). There was no change in average LDL particle size. Similar results were seen with atorvastatin, with a 44% reduction in LDL-C but only a 33% reduction in LDL particles. Differences were also seen between increases in HDL-C and HDL particles, although rosuvastatin raised each to a significantly greater extent compared with atorvastatin, Dr. Rosensen noted.
Dr. Rosensen and colleagues further analyzed the effects of the 2 statins on LDL particles and LDL-C in these patients by calculating the proportion achieving LDL-C < 100 mg/dL (< 20th percentile of NHANES III), those achieving LDL particle concentrations < 1000 nmol/L (< 20th percentile according to the Multi-Ethnic Study of Atherosclerosis [MESA] scale), and those achieving LDL particle concentration below 1300 nmol/L (< 50th MESA percentile). They found that most patients achieved LDL-C < 100 mg/dL and LDL-particle < 1300 nmol/L goals after 6 and 12 weeks of treatment, although reductions in both LDL-C and LDL particles were smaller with atorvastatin ( Table 12 ). However, far fewer patients (12% to 27%) reached the more appropriate LDL particle goal of < 1000 nmol/L, Dr. Rosensen noted.
These results lend further support to the ADA/ACCF consensus report on lipoprotein management in patients with the metabolic syndrome, Dr. Rosensen said. He noted that there are some "underappreciated" classes of agents such as fibrates and nicotinic acid that lower LDL particle concentration more than LDL-C. "Fenofibrate lowers LDL-C by only 8% but lowers LDL particles by 19% and apoB by 16%," he said. "There is a disconnect between how certain agents lower LDL-C versus how they lower LDL particle concentration."
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Cite this: Should LDL-Cholesterol Particle Concentrations Replace LDL Levels to Assess Risk? - Medscape - Feb 16, 2009.