The LP-PLA2 Test For Cardiovascular Risk

Do you really need it?

atherosclerosis of coronary artery
atherosclerosis of coronary artery. Ed Reschke/Getty images

If your doctor thinks you may be at increased risk for a myocardial infarction (heart attack) or stroke, he or she might recommend a blood test called the lipoprotein-associated phospholipase A2 (LP-PLA2) test. The LP-PLA2 test, many believe, can help to characterize just how elevated your cardiovascular risk may be.

What Is LP-PLA2?

LP-PLA2 is an enzyme that is produced mainly by white blood cells within the walls of arteries.

This enzyme has several functions, but one of its chief effects is to facilitate the participation of LDL cholesterol in the inflammatory processes that lead to atherosclerosis.

Perhaps the best way of looking at LP-PLA2 is that it is a marker of vascular inflammation. In this way, it is similar to the better-known C-reactive protein (CRP), except that LP-PLA2 indicates inflammation specifically within the blood vessel walls. (CRP levels, in contrast, can be elevated as a result of numerous inflammatory processes around the body.) Indeed, LP-PLA2 activity is quite high within the core of atherosclerotic plaques themselves. Therefore, at least in theory, the LP-PLA2 test should be a much more specific marker than CRP for ongoing atherosclerosis.

So, the LP-PLA2 test can be used to help detect whether atherosclerosis is likely to be present, and therefore, to help define a person’s long-term risk of heart attack and stroke.

How Useful Is The LP-PLA2 Test?

Clinical studies have shown that elevated LP-PLA2 levels correlate with an increased risk of heart attack and stroke. In general, the higher the LP-PLA2 levels, the higher the subsequent cardiovascular risk.

In 2008, a consensus panel of experts concluded that LP-PLA2 testing could be useful in characterizing the cardiovascular risk of patients whose traditional risk factors placed them into an “intermediate risk” category.

Specifically, the panel found, if a patient’s LP-PLA2 levels are higher than 200 ng/mL, his or her long-term cardiovascular risk should be considered high, rather than intermediate - and therefore, that measures to reduce cardiovascular risk should become more aggressive.

Can High LP-PLA2 Levels Be Treated?

There are no clinical studies demonstrating that reducing your LP-PLA2 level itself reduces your risk. Most experts consider LP-PLA2 levels to be a marker of risk rather than a target for therapy.

However, it turns out that LP-PLA2 levels can be reliably reduced with statin drugs, aspirin, weight loss, smoking cessation, and a reduced-carbohydrate diet.

The Bottom Line - Should You Be Tested?

In general, LP-PLA2 testing is not necessary to adequately assess a person's cardiovascular risk, since standard risk assessment measures are usually accurate enough. More importantly, standard risk assessment generally points out the things you need to be doing to reduce your risk as much as possible, such as diet, weight, exercise, not smoking, and controlling blood pressure.

Most of these are the very things, it turns out, that will also reduce your LP-PLA2 levels. But in most cases measuring LP-PLA2 is not necessary to reveal that a person’s lifestyle could use a little cleaning up.

There is at least one instance, however, where LP-PLA2 testing may be helpful. If you and your doctor are on the fence on deciding about statin therapy, knowing that your LP-PLA2 level is elevated (and therefore, that active atherosclerosis is probably taking place) may push you both into the “decided” column. Any medical test is helpful whenever knowing its results will help you to make a decision.

Sources:

Davidson MH, Corson MA, Alberts MJ, et al. Consensus panel recommendation for incorporating lipoprotein-associated phospholipase A2 testing into cardiovascular disease risk assessment guidelines. Am J Cardiol. 2008;101(suppl):51F-57F.

Corson MA, Jones PH, Davidson MH. Review of the evidence for the clinical utility of lipoprotein-associated phospholipase A2 as a cardiovascular risk marker. Am J Cardiol. 2008;101 (suppl):41F-50F.

Tsimikas S, Willeit J, Knoflach M, et al. Lipoprotein-associated phospholipase A2 activity, ferritin levels, metabolic syndrome, and 10-year cardiovascular and non-cardiovascular mortality: Results from the Bruneck study. Eur Heart J. 2009;30:107-115.

Lp-PLA(2) Studies Collaboration,Thompson A, Gao P, Orfei L, et al. Lipoprotein-associated phospholipase A(2) and risk of coronary disease, stroke, and mortality: Collaborative analysis of 32 prospective studies. Lancet. 2010;375:1536-1544.

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