Lipoprotein (a) is increased in acute coronary syndromes (unstable angina pectoris and myocardial infarction), but it is not predictive of the severity of coronary lesions

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.

Lipoprotein(a) is related to the extent of lesions in the coronary vasculature and to unstable coronary syndromes

BACKGROUND

Lp(a) is a highly atherogenic particle with a prothrombotic effect. Until now its relation to the extent and severity of the atheromatic lesions had not been established by standard procedures.

HYPOTHESIS

This study examined the correlation of Lp(a) to the extent and severity of coronary artery disease (CAD) and its relation to unstable clinical events (not including sudden death).

METHODS

In 202 patients undergoing coronary angiography, plasma lipids were measured with the usual procedures and Lp(a) with the enzyme-linked immunosorbent assay. The extent of CAD was expressed in the number of diseased vessels and its severity in terms of the severity coefficient and the obstruction coefficient.

RESULTS

A very strong relationship between LP(a) and the number of diseased vessels (p = 0.0007) signifying diffuse atherosclerosis, but no relation with the severity of the lesions. was found. However, it was the only lipid that correlated significantly with the number of totally occluded vessels (p = 0.0003). The thrombogenic ability of Lp(a) was manifested by increased incidence of myocardial infarction and unstable angina episodes in patients with elevated Lp(a) (p = 0.0157).

CONCLUSION

Elevated Lp(a) predisposes to the extent of CAD and total occlusions but not to the severity of lesions. Patients with increased Lp(a) levels and unstable angina are at increased danger of suffering myocardial infarction. Thus, Lp(a) may predispose to plaque destabilization and thrombosis of noncritical lesions.

Novel cardiovascular risk factors

In addition to the well-established cardiovascular risk factors of elevated total and low-density lipoprotein cholesterol, hypertension, and cigarette smoking, multiple additional factors are suspected culprits in both the development and progression of atherothrombosis. It is key for the clinician to critically review research findings utilizing an organized framework in order to credibly advise the patient with cardiovascular disease or at risk for its development. The current evidence and recommendations regarding the following "novel"or "emerging" risk factors will be reviewed: lipoprotein(a), hyperhomocysteinemia, C-reactive protein, infectious processes, fibrinogen, and microalbuminuria.

[Lipoprotein (a) as a predictor of severity of coronary artery stenosis documented by angiography in male coronary patients under 50 years old]

OBJECTIVE

To determine the relationship between lipoprotein (a) seric levels with the age of coronary artery disease debut and the severity of coronary lesions in a group of male patients less than 50 years old.

PATIENTS AND METHODS

We studied a group of 230 male patients, younger than 50 who were consecutively admitted to the hospital because of an ischemic coronary event. During hospitalization, the lipoprotein (a) in plasma was measured in all patients. They were distributed in two groups according to age at time of coronary disease clinical presentation with a cut off age of 40. A group of 142 patients underwent a cardiac catheterism and coronariography due to clinical or electrical unstability.

RESULTS

The lipoprotein (a) levels were related with the number of diseased vessels. In this way lipoprotein (a) levels were 12 mg/dl (1.5-75) in those patients showing a normal coronariography; 27 mg/dl (2. 5-96) in those with one vessel disease; 34 mg/dl (7-90) in those with two vessels affected and 63 mg/dl (2-116) in the case of three-vessel disease, with statistical significance of p = 0.003. No significant differences in lipoprotein (a) levels were found when the age of coronary artery disease presentation was taken into account. In this way lipoprotein (a) levels were 31 mg/dl (2-97) in patients younger than 40 years of age, in comparison to 33 mg/dl (2-94) in those older than 40.

CONCLUSIONS

In our community male patients with a diagnosis of coronary artery disease and less than 50 years old showed a relationship between lipoprotein (a) levels and the severity and number of coronary vessel diseases. However, an association between lipoprotein (a) levels with the age of coronary disease presentation was not evident.

Novel risk factors for coronary heart disease: emerging connections

In only 50% of cases of coronary heart disease (CHD) is the cause attributable to the established risk factors of hypertension, cigarette smoking, and elevated total and low-density lipoprotein (LDL) cholesterol levels. This finding has led to research examining other markers for CHD that may have a causal link to the atherothrombotic process. Several of these "emerging" risk factors are reviewed in this article: lipoprotein(a); small dense LDL particle size; hyperhomocysteinemia; and inflammatory, infectious, and hemostatic factors. Evaluation of each of these factors includes a review of the epidemiologic evidence, examination of the pathologic mechanism(s) by which the factor might participate in atherothrombosis, and the clinical utility of screening. Finally, and most relevant for the practicing clinician, the following is addressed: Does evidence exist that selective modification of these risk factors is associated with net clinical benefit?