Serum lipoprotein(a) level and clinical coronary stenosis progression in patients with myocardial infarction: re-revascularization rate is high in patients with high-Lp(a)

High Lipoprotein(a) Levels as a Predictor of Major Adverse Cardiovascular Events in Hospitalized-Acute Myocardial Infarction Patients

Background

Risk stratification models with incorporation of biochemical markers have received attention recently. In acute myocardial infarction (AMI) one such marker is lipoprotein(a) (Lp(a)). Lp(a) has prothrombotic and proinflammatory properties. High levels of Lp(a) probably contribute to the additional adverse effects in AMI, as it enhances the damaging effect of acute thrombosis. This study aimed to evaluate serum Lp(a) as a predictor of major adverse cardiovascular events (MACE) in hospitalized-acute myocardial infarction patients.

Methods

A prospective cohort study was conducted at Sanglah Hospital, Denpasar, during June–August 2018, among 66 people by consecutive sampling. Samples that met the inclusion and exclusion criteria were examined for serum Lp(a) at the time of admission and the occurrence of MACE during hospitalization was observed. Data regarding serum Lp(a), demography, smoking history, dyslipidemia, hypertension, diabetes mellitus, and MACE were collected. Log rank test and Cox proportional hazards regression were conducted with SPSS version 20 for Windows.

Results

During observation, MACE occurred in 25 (38%) patients, including cardiogenic shock in 7 (10.6%) patients, heart failure in 20 (30.3%) patients, cardiovascular death in 5 (7, 6%) patients, malignant arrhythmias in 5 (7.6%) patients, and postinfarction angina in 5 (7.6%) patients. After the Log rank test, a significant difference in survival was observed (p = 0.001) between groups of high Lp(a) (survival rate of 60.6 hours; 95% CI 43.3–77.9) and low Lp(a) (average survival of 104.3 hours, 95% CI 91.4–117.2). The hazard ratio of high Lp(a) against MACE was 4.63 (p=0.002), and it increased to 4.69 in multivariate analysis with Cox proportional hazards regression test (p=0.003).

Conclusion

The high level of Lp(a) in AMI patients was a risk factor for the occurrence of MACE during hospitalization. Patients with high Lp(a) also had worse survival compared to patients with low Lp(a).

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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.

Potential of lipoproteins as biomarkers in acute myocardial infarction

Acute myocardial infarction (AMI), commonly known as heart attack, is a medical emergency that is potentially fatal if not promptly and properly managed. The early diagnosis of AMI is critically important for the timely institution of pharmacotherapy to prevent myocardial damage and preserve cardiac function. Ischemic insults during AMI cause myocardial tissue damage, releasing the cardiac muscle protein troponin T into the blood stream. Therefore, serum troponin T levels are used as a sensitive and specific indicator of myocardial injury for diagnosing AMI. However, there remains a requirement for developing technologies for more accurate biomarkers or signatures for AMI diagnosis or prognosis. Previous studies have implicated impaired lipid metabolism as a causative factor in AMI development. Lipoproteins are important constituents of lipid metabolism; their levels in the blood stream are a convenient biomarker tool for monitoring lipid metabolism. This review summarizes recent findings (data of studies from 2001 to 2016) regarding the biomarker potentials of various lipoproteins, including low-density lipoprotein, oxidized low-density lipoprotein, high-density lipoprotein, lipoprotein-a, and remnant lipoprotein, for the risk stratification of AMI.

Lipoprotein(a) in cardiovascular diseases

Lipoprotein(a) (Lp(a)) is an LDL-like molecule consisting of an apolipoprotein B-100 (apo(B-100)) particle attached by a disulphide bridge to apo(a). Many observations have pointed out that Lp(a) levels may be a risk factor for cardiovascular diseases. Lp(a) inhibits the activation of transforming growth factor (TGF) and contributes to the growth of arterial atherosclerotic lesions by promoting the proliferation of vascular smooth muscle cells and the migration of smooth muscle cells to endothelial cells. Moreover Lp(a) inhibits plasminogen binding to the surfaces of endothelial cells and decreases the activity of fibrin-dependent tissue-type plasminogen activator. Lp(a) may act as a proinflammatory mediator that augments the lesion formation in atherosclerotic plaques. Elevated serum Lp(a) is an independent predictor of coronary artery disease and myocardial infarction. Furthermore, Lp(a) levels should be a marker of restenosis after percutaneous transluminal coronary angioplasty, saphenous vein bypass graft atherosclerosis, and accelerated coronary atherosclerosis of cardiac transplantation. Finally, the possibility that Lp(a) may be a risk factor for ischemic stroke has been assessed in several studies. Recent findings suggest that Lp(a)-lowering therapy might be beneficial in patients with high Lp(a) levels. A future therapeutic approach could include apheresis in high-risk patients in order to reduce major coronary events.

High Lipoprotein(a) Levels are Associated With Long-Term Adverse Outcomes in Acute Myocardial Infarction Patients in High Killip Classes

Background and Objectives

An elevated concentration of lipoprotein(a) {Lp(a)} is associated with an increased prevalence and increased severity of coronary artery disease. However, the relationship between Lp(a) levels and outcomes after acute myocardial infarction (AMI) is unclear.

Subjects and Methods

Between October 2005 and June 2007, we measured serum Lp(a) levels in 832 consecutive AMI patients (age, 62.8±12.4 years, 600 men) on admission. They were divided into tertiles according to their serum Lp(a) levels {Tertile 1 (n=276), Lp(a)<13.8 mg/dL; Tertile 2 (n=279), Lp(a)=13.8-30.6 mg/dL; Tertile 3 (n=277), Lp(a)>30.6 mg/dL}.

Results

There were no differences in baseline clinical characteristics among Tertiles 1, 2, and 3, except for proportions of Killip class III-IV patients (5.8% vs. 10.0% vs. 18.8%, respectively, p<0.001). There were significant differences in left ventricular ejection fractions (57.3±11.4% vs. 55.9±12.3% vs. 53.1±13.1%, p<0.001). Among the laboratory findings, there were significant differences in total cholesterol (173.3±37.2 vs. 183.5±38.9 vs. 185.3±43.8 mg/dL, p=0.001), low density lipoprotein-cholesterol (111.3±34.3 vs. 122.9±34.7 vs. 123.3±39.4 mg/dL, p<0.001), apolipoprotein B (92.8±25.4 vs. 100.8±26.0 vs. 101.9±28.8 mg/dL, p<0.001), and amino-terminal pro-brain natriuretic peptide levels (1805.2±4343.3 vs. 2607.9±5216.3 vs. 3981.5±7689.7 pg/mL, p<0.001). After adjusting for multiple variables in the high Killip class (III-IV) subgroup, the risk estimate for major adverse cardiovascular events (MACE) at 1-year follow-up was significantly higher in Tertile 3 than in Tertiles 1 or 2 (hazard ratio 6.723, 95% confidence interval 1.037-43.593, p=0.046).

Conclusion

In patients in high Killip classes, high serum levels of Lp(a) were significantly associated with long-term adverse outcomes after AMI.

Lipoprotein(a) and other serum lipid subfractions influencing primary patency after infrainguinal percutaneous transluminal angioplasty

PURPOSE

To evaluate the influence of serum lipid subfraction concentrations on arterial patency after percutaneous transluminal angioplasty (PTA) in patients with infrainguinal peripheral artery occlusive disease (PAOD).

METHODS

From January 2007 to June 2008, a prospective study was conducted involving 39 patients (29 men; mean age 68.6+/-10.0 years) with infrainguinal PAOD in 41 limbs who had preprocedural lipid assessment and underwent successful PTA (<30% residual stenosis). Patient demographics, Fontaine clinical stage classification, Texas University Classification of ulcers, coexisting medical conditions, endovascular procedures, and lipid profiles were collected in a database. Follow-up included clinical and duplex ultrasound evaluation at discharge and at 1, 3, 6, and 12 months. To analyze any correlation between various lipid subfractions and the loss of primary patency (Cox proportional hazards modeling), the patients were dichotomized into high and low groups according to these thresholds: LDL-C >100 mg/dL, HDL-C <40 mg/dL, Lp(a) >30 mg/dL, and an Apo(B)/Apo(A) ratio >0.8 mg/dL.

RESULTS

Mean follow-up was 7.5 months (range 3-12). After 1, 3, and 6 months, the primary patency rates by Kaplan-Meier analysis were 94.9%, 73.7%, and 64.1%, respectively. Restenosis at 6 months was significantly related to female gender (HR 95.9, 95% CI 6.8 to 1352.5, p = 0.001), HDL-C <40 mg/dL (HR 86.9, 95% CI 6.4 to 1183.1, p = 0.001), LDL-C >100 mg/dL (HR 9.6, 95% CI 1.6 to 57.4, p = 0.013), and Lp(a) >30 mg/dL (HR 6.1, 95% CI 1.4 to 26.3, p = 0.016).

CONCLUSION

Our results suggest that Lp(a), LDL-C, and HDL-C are independent risk factors for restenosis after infrainguinal PTA.

Plasma levels of lipoprotein (a) in patients with major depressive disorders

Depression and cardiovascular disease are among the most prevalent health problems. The evidence that depression is a risk factor for the development and progression of coronary heart disease has strengthened over the past several years, but the exact reasons are not yet clear. Elevated lipoprotein (a) (Lp(a)) concentrations seem to be the major factor for the progression of the atherosclerosis and coronary heart disease. In this study, we measured the plasma levels of Lp(a) in 35 patients with major depressive disorder and 35 healthy controls. The two groups were matched by age and gender. Lp(a) measurement was performed using an immunoturbidimetric method. Total cholesterol was significantly lower in the patient group (mean +/-SD: 144.65+/-22.13 vs. 186.14+/-34.48 mg/dl. The Lp(a) levels of the patient group differed significantly from control values. Patients with major depressive disorder had higher plasma levels of Lp(a) than healthy controls (34.94+/-18.01 vs. 20.08+/-11.27 mg/dl). The results of the present study suggest that the increase of Lp(a) may contribute to higher cardiovascular risk in patients with major depressive disorder.

Hyperlipoproteinaemia(a) is a common cause of autosomal dominant hypercholesterolaemia

Autosomal dominant hypercholesterolaemia (ADH) are a heterogeneous group of monogenic lipid disorders. The plasma level of lipoprotein(a) (Lp(a)) is a heritable trait associated with increased coronary heart disease (CHD) risk.

OBJECTIVE

To evaluate the frequency of elevated Lp(a) as a cause of ADH and the characteristics of subjects with high Lp(a) (hyperLp(a)).

MATERIAL AND METHODS

200 healthy subjects and 933 unrelated Spanish subjects with a clinical diagnosis of ADH who were screened for low-density lipoprotein receptor (LDLR) and apolipoprotein B (APOB) gene mutations. Standard cardiovascular risk factors and blood lipid levels, including Lp(a), were evaluated. HyperLp(a) was defined as Lp(a) levels >or=95th centile of control values.

RESULTS

Lp(a) was higher in 263 subjects without LDLR or APOB mutations (nonLDLR/nonAPOB group) than in 670 subjects with mutations (FH group): 40.0 mg/dl (interquartile range (IR) 15.0-89.0) versus 31.0 mg/dl (IR 11.0-73.7) respectively, p = 0.002. HyperLp(a) was present in 23% of ADH subjects (odds ratio (OR) 5.6 (95% CI, 2.9 to 10.7) versus controls) and 29% of nonLDLR/nonAPOB subjects (OR 7.7; 3.9 to 15.4). After adjusting for Lp(a), LDL cholesterol levels were <95th centile in 28 (10.6%) nonLDLR/nonAPOB subjects and in 9 (1.3%) FH subjects. Lp(a) levels were nonsignificantly higher in ADH subjects with early-onset CHD than in those without (43.5 mg/dl, (IR, 12.0-82.0) versus 31.7 mg/dl (11.8-76.5), respectively).

CONCLUSIONS

HyperLp(a) is responsible for ADH in approximately 6% of nonLDLR/nonAPOB subjects. HyperLp(a) would not appear to be a risk factor for early-onset CHD in ADH, independently of whether genetic defects have or have not been demonstrated.