The Skeptical Cardiologist

Should You Get Tested For Lipoprotein(a), The “Hidden” Risk Factor For Cardiovascular Disease?

The skeptical cardiologist wrote about the importance of testing patients with premature atherosclerosis or strong family history of cardiovascular disease for Lipoprotein(a) here.

The National Lipid Association (NLA) published their scientific statement on Lipoprotein(a) (Lp(a)) (Use of Lipoprotein(a) in Clinical Practice: A Biomarker Whose Time Has Come) last summer (summarized nicely here) and I’ve listed their key recommendations below.

  1. For diagnosing high Lp(a) they chose a universal cut point of >100 nmol/L (approximately >50 mg/dl) which is at the 80th percentile in white Americans. This cut-off is not written in stone and may vary depending on risk, ethnicity, and comorbidities. Some labs report out Lp(a) in mg/dl, others in nmol/L. Pay attention to the units.
  2. An individual’s Lp(a) level is 80-90% genetically determined in an autosomal codominant inheritance pattern with full expression by 1-2 years of age and adult-like levels achieved by approximately 5 years of age. Outside of acute inflammatory states, the Lp(a) level remains stable through an individual’s lifetime regardless of lifestyle.

  3. High-quality evidence supports a link between Lp(a) levels and a variety of cardiovascular-related outcomes. See Table 1. The risk of heart attack and aortic stenosis is increased 3 to 4 fold.

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4. The following populations should be considered for testing.

5. Neither diet nor lifestyle influences Lp(a) levels.

6. PCSK9 inhibitor drugs and niacin lower Lp(a) levels and but there are no data showing this changes clinical outcomes.

7. Similar to my approach, “the authors recommend initiating a moderate- to high-intensity statin therapy in adults aged 40-75 years with a 10-year ASCVD risk of 7.5% to ≤20% with a Lp(a) ≥100 nmol/L. High-risk patients with LDL-C ≥70 mg/dL (non-HDL-C ≥100 mg/dL) and a Lp(a) ≥100 nmol/L on maximally tolerated statin should be considered for more intensive therapies (ezetimibe and PCSK9 inhibitors) to lower LDL-C.”

8. Currently, novel therapies are being studied that selectively target Lp(a). A phase 2 trial of AKCEA apo(a)-LRx, an apo(a) antisense oligonucleotide, reduced Lp(a) up to 80%. A phase 3 study is being planned. Additionally, an oxPL antibody that binds and inactivates the pro-osteogenic activity of Lp(a) has promising in vitro data. These therapies, while promising, require additional research prior to becoming mainstream therapies.

The cost of the blood test for Lp(a) should be minimal. Medicare reimburses $14 for it. You can order it from Boston Heart Diagnostics for $11. Unfortunately, there is no telling what your local hospital lab will charge.

Since Lp(a) is inherited, patients with high levels should consider having first-degree relatives tested for Lp(a) to identify those who are going to be at high risk. This provides an early warning of who in the family is most at risk for cardiovascular complications early in life. Such patients should be considered for early screening for subclinical atherosclerosis. In addition, they should be additionally motivated to do everything possible to reduce their elevated risk by lifestyle changes.

Proantiatherogenically Yours,

-ACP

N.B. In 2018 the Centers for Disease Control and Prevention (CDC) approved two ICD-10 codes for the diagnosis of elevated Lipoprotein(a), or Lp(a). The ICD-10 diagnosis codes help to identify asymptomatic patients with elevated Lipoprotein(a) (E78.41) and a family history of elevated Lipoprotein(a) (Z83.430)

N.B.2. Don’t confuse Lp(a) with Apolipoprotein A1 which is the major protein component of HDL particles in plasma. Also, please note that WordPress converted my little a into a capital A in the title and I have no idea how to prevent that conversion.

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