Show 1421: Is Lp(a) the Heart Risk No One Talks About?

This week, we get in-depth information on Lp(a), the heart risk no one talks about. You have heard of cholesterol, and you may even know what your cholesterol level is. The compound lipoprotein a may be equally dangerous when it is elevated, but you have probably heard very little about it.

What Is Lp(a)?

Lipoprotein a, or L-P-little a for short, circulates in the bloodstream, where it picks up and carries cholesterol and oxidized phospholipids. Scientists believe that blood levels are determined mostly by genetics and change very little over the course of our lives. Roughly 20 percent of people have high levels of Lp(a), above 30 ng/dL or 75 nmol/L. The two different figures are because tests use different units to measure the blood concentration, either nanograms per deciliter or nanomols per liter.

While we don’t know if Lp(a) has or perhaps once had some important functions, we do know that elevated levels of this chemical is associated with heart disease. People with higher levels are more likely to suffer blood clots and inflammation. That puts them at risk for heart attacks or even strokes. So why hasn’t your doctor ordered a blood test to learn your level?

Is Lp(a) the Heart Risk Doctors Can’t Treat?

Perhaps doctors have been reluctant to measure or discuss lipoprotein a because they don’t have good interventions. That is beginning to change with the development of antisense oligonucleotides, a new category of prescription drugs that can cut levels sharply. The FDA has not yet approved any of these new medications, though. The first of these, pelacarsen, is still in Phase 3 trials needed before the agency can consider the evidence. However, it can bring down lipoprotein a by an estimated 80 percent.

Cardiologists’ favorite drugs, statins, do not help Lp(a) levels. In fact, Lp(a) the heart risk rises when people are taking statins to lower their cholesterol. Other cholesterol-lowering drugs such as evolocumab (Repatha) and alirocumab (Praluent) can bring Lp(a) levels down modestly. One really old cholesterol-lowering drug, high-dose niacin, also helps moderate Lp(a). Some people do not tolerate it, however, as it can cause very uncomfortable flushing. So far as we know, no scientists have run studies to see whether niacin reduces the risk of heart attacks and other complications because of its effects on Lp(a).

Other Complications of Lp(a):

Our guest, Dr. Sam Tsimikas, is among the country’s leading experts on lipoprotein a. We asked him whether Lp(a) the heart risk factor causes other problems as well. Dr. Tsimikas described heart failure, potentially resulting from a heart attack, as well as peripheral artery disease (PAD), which can make it painful to walk. Lp(a) seems to cause plaque in arteries throughout the body. As a result, it can increase the chance of a stroke. In addition, it contributes to calcification of the heart valves. This condition interferes with their ability to function properly.

What Can We Do If Lp(a) Is Too High?

Dr. Tsimikas runs a unique clinic for cardiology patients with high levels of Lp(a). We asked him how he helps them. One approach is to collect additional information about their level of risk. A coronary calcium score can be a useful indicator. If it is high, he and his patients work to control all the potential risk factors that they can. He discusses the potential benefit of aspirin with them. Because Lp(a) the heart risk factor increases the chance of dangerous blood clots, the anti-clotting activity of aspirin can sometimes be helpful.

Offering dietary advice can be tricky if a patient has high cholesterol as well as elevated Lp(a), since the ideal diets for each are nearly opposite each other. A ketogenic diet tends to raise LDL cholesterol, for example, while it may modestly lower Lp(a). We think by the end of this episode, you’ll join us in hoping that scientists can learn a lot more about Lp(a) in the next few years.

This Week's Guest:

Sotirios (Sam) Tsimikas, MD, FACC, FAHA, FSCAI, is Professor of Medicine/Cardiology and Director of Vascular Medicine at the Sulpizio Cardiovascular Center. That is part of the Division of Cardiovascular Medicine at the University of California, San Diego. His website is https://profiles.ucsd.edu/sotirios.tsimikas

[caption id="attachment_134327" align="alignnone" width="768"] Sotirios (Sam) Tsimikas, MD, FACC, FAHA, FSCAI, UCSD[/caption]