Elevated levels of low-density lipoprotein cholesterol, homocysteine, and lipoprotein(a) are associated with the occurrence of symptomatic bypass graft disease 1 year following coronary artery bypass graft surgery

Lipoprotein(a): An independent, genetic, and causal factor for cardiovascular disease and acute myocardial infarction

Lipoprotein(a) [Lp(a)] is a circulating lipoprotein, and its level is largely determined by variation in the Lp(a) gene (LPA) locus encoding apo(a). Genetic variation in the LPA gene that increases Lp(a) level also increases coronary artery disease (CAD) risk, suggesting that Lp(a) is a causal factor for CAD risk. Lp(a) is the preferential lipoprotein carrier for oxidized phospholipids (OxPL), a proatherogenic and proinflammatory biomarker. Lp(a) adversely affects endothelial function, inflammation, oxidative stress, fibrinolysis, and plaque stability, leading to accelerated atherothrombosis and premature CAD. The INTER-HEART Study has established the usefulness of Lp(a) in assessing the risk of acute myocardial infarction in ethnically diverse populations with South Asians having the highest risk and population attributable risk. The 2018 Cholesterol Clinical Practice Guideline have recognized elevated Lp(a) as an atherosclerotic cardiovascular disease risk enhancer for initiating or intensifying statin therapy.

Plasma homocysteine levels are related to medium-term venous graft degeneration in coronary artery bypass graft patients

Objective:

Saphenous venous grafts (SVGs) are established choices for coronary artery bypass grafting (CABG); however, their lumen patency is limited. Our goal was to investigate the risk factors of SVG degeneration.

Methods:

Seventy-five patients (mean age, 57.5±10.4 years) with 133 SVG conduits who had cardiac catheterization ≥1 year after CABG were selected; follow-up period was 67.6±36.8 months. Patients were divided into 3 groups according to angiographic status at follow up [intact: <20% (n=23); narrowed: 20–99% (n=24); and occluded (n=28)]. Baseline clinical conditions were evaluated in relation to follow-up angiography. As onset date of chronic total occlusions is usually uncertain, they arise typically from thrombotic lesions; thus, their value in evaluation is limited.

Results:

There were no significant differences between the 3 groups in clinical parameters. Linear correlation analysis found significant (p<0.01) positive connection of SVG disease (luminal diameter reduction 20–99%) with C-reactive protein (CRP) and homocysteine (Hcy), as well as between CRP and Hcy. Multiple regression analysis showed plasma Hcy level to be significantly related to graft diameter reduction normalized to time elapsed until angiography in narrowed grafts: 1 µmol/L increase of Hcy was associated with 0.053%/month decrease in lumen diameter (p<0.01; R²=0.428); extrapolating: +10 µmol/L higher Hcy level during 5 years is associated with 32.1% lumen reduction.

Conclusion:

Medium- to long-term SVG degeneration is related to elevated plasma total Hcy in patients with sub-occlusive graft stenosis, while in cases with intact SVGs, the beneficial local flow conditions may protect the grafts from degeneration.

Lipoprotein(a) level and apolipoprotein(a) phenotype as predictors of long-term cardiovascular outcomes after coronary artery bypass grafting

OBJECTIVE

To evaluate the relationships of lipoprotein(a) (Lp(a)) concentration and apolipoprotein(a) (apo(a)) phenotype to major adverse cardiovascular events after coronary artery bypass grafting (CABG) in long-term follow-up.

METHODS

This single-center study included 356 patients with stable coronary heart disease (CHD) who underwent successful CABG. At baseline, we assessed the patient's risk factor profile for atherosclerosis, Lp(a) concentration and apo(a) phenotype. The primary endpoint was the composite of cardiovascular death and non-fatal myocardial infarction (MI). The secondary endpoint also included hospitalization for recurrent or unstable angina and repeat revascularization.

RESULTS

Over a mean of 8.5 ± 3.5 years (range 0.9-15.0 years), the primary and secondary endpoints were registered in 46 (13%) and 107 (30%) patients, respectively. Patients with Lp(a) ≥30 mg/dL were at significantly greater risk for the primary endpoint (hazard ratio (HR) 2.98, 95% confidence interval (CI) 1.76-5.03, p < 0.001) and secondary endpoint (HR 3.47, 95% CI 2.48-4.85, p < 0.001) than patients with Lp(a) values <30 mg/dL. The low molecular-weight apo(a) phenotype was also associated with higher risk of both primary and secondary endpoints (3.57 (1.87-6.82) and 3.05 (2.00-4.62), respectively; p < 0.001 for both), regardless of conventional risk factors and statins use.

CONCLUSION

In stable CHD patients Lp(a) concentration and low molecular-weight apo(a) phenotype are independently associated with three-fold increase in risk of major adverse cardiovascular events within 15 years after CABG. Lp(a) levels may provide an additional information for postoperative cardiovascular risk assessment.