Lp(a) predicts coronary atherosclerosis and revascularization
MedWire News: Levels of lipoprotein (Lp)(a) correlate with the extent of coronary atherosclerosis, vascular events, and need for revascularization in patients with suboptimal lipid control, a 3-year study has found.
The authors say this result supports the need to intensify lipid management in patients with elevated Lp(a) levels.
Stephen Nicholls (Cleveland Clinic, Ohio, USA) and team investigated the relevance of Lp(a) levels in patients undergoing elective coronary angiography. Nearly all patients had significant coronary stenosis in at least one vessel and 42.5% of patients had three-vessel disease.
The median Lp(a) level at baseline was 16.4 mg/dl. During 3 years of follow-up 36.6% of patients experienced major adverse cardiovascular events (MACE) - 25.6% coronary revascularization, 10.5% death, 5.2% myocardial infarction, and 1.1% stroke.
For the analysis, Nicholls' team divided patients into two groups according to their baseline Lp(a) level: less than 30 mg/dl (n=1720) or 30 mg/dl or above (n=1049).
Patients with low Lp(a) levels tended to be younger, were less likely to be Caucasian or diabetic, more likely to have hyperlipidemia, and had a lower body mass index than those with high Lp(a) levels.
High Lp(a) levels were also associated with a greater prevalence of coronary artery disease, peripheral artery disease, coronary artery bypass grafting, and statin treatment.
After adjusting for these baseline differences, elevated Lp(a) levels were associated with a 2.3-fold increased risk for angiographic stenosis, a 1.5-fold increased risk for three-vessel disease, a 1.2-fold higher risk for MACE, and a 1.2-fold higher risk for coronary revascularization.
Interestingly, subgroup analysis showed that the relationship between Lp(a) and cardiovascular outcomes was present in patients with low-density lipoprotein (LDL) cholesterol levels above 100 mg/dl (2.59 mmol/l) and between 70 and 100 mg/dl (1.81-2.59 mmol/l) but not in those with levels below 70 mg/dl (1.81 mmol/l).
A genetic substudy revealed that four single nucleotide polymorphisms (SNPs) and two four-SNP haplotypes at the LPA locus were significantly associated with plasma Lp(a) levels. Some of these variants were also associated with coronary stenosis but none were associated with MACE.
Commenting on their subgroup analysis, Nicholls et al write: "The present findings thus suggest that Lp(a) is an important marker of cardiovascular risk that identifies patients who are likely to derive more clinical benefit from intense lipid lowering with reduction of LDL cholesterol to <70mg/dl."
They add: "It is important to note, however, that the current analysis is unable to determine whether Lp(a) plays a direct role in disease pathogenesis in these patients or simply acts as a marker of elevated cardiovascular risk."
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By Joanna Lyford