The PLAC Test

Patient Expert

We now have a test that can determine hidden risks of heart attack and stroke. It's called the PLAC Test and is the only blood test that the U.S. Food and Drug Administration has approved.

The PLAC test helps us identify hidden risks for heart attack and stroke by measuring for Lp-PLA2. This is the cardiovascular-specific inflammatory enzyme implicated in the formation of vulnerable, rupture-prone plaque.

The conditions that this test helps to identify are two of the country's three most serious health problems. The American Heart Association estimates that at least 65 percent of people with diabetes will die from a cardiovascular event, such as a heart attack or stroke.
Fortunately, we have a simple blood test that goes beyond traditional risk factors to help identify those of us at increased risk of heart disease and stroke. ThePLAC Test, developed by diaDexus Inc. in South San Francisco, can help us assess our risk for both conditions. Lp-PLA2 is an enzyme in the blood primarily associated with low-density lipoprotein (LDL, the "bad" cholesterol). LDL carries Lp-PLA2 to the walls of coronary arteries. There the enzyme can activate an inflammatory response, making plaque more prone to rupture.

As a result, Lp-PLA2 serves as a specific indicator of vascular inflammation. People who the test identify as being at high risk for heart attack or stroke based on their elevated Lp-PLA 2 levels may benefit from more aggressive treatment programs, such as lifestyle modification or therapeutic intervention. In addition, GSK Pharmaceuticals is in Phase 3 development of an Lp-PLA2 inhibitor called darapladib.

A substantial body of evidence, including more than 65 studies and abstracts in peer-reviewed journals and conferences, support Lp-PLA2 as a cardiovascular risk marker that provides new information beyond the traditional risk factors. But the key recommendation is the consensus panel recommendation for the test in the June 2008 issue of The American Journal of Cardiology.

The consensus panel concluded that an Lp-PLA2 level above 200 ng/ml warrants reclassifying the patient to a higher risk category that would require more aggressive treatment of the high cholesterol levels. I got my doctor to prescribe the test. My level was 217 ng/ml, which is in the "moderate risk" area up to 235, where the high risk area starts.

Big surprise My most recent lipid panel showed that my LDL level was an excellent 74, my HDL level was a great 69, and my triglycerides were just 43. Why was my Lp-PLA2 moderately high?

I asked Michael Wegner, PhD., who is directory of medical affairs for diaDexus. Age is a non-modifiable risk factor, and at age 74 one that I certainly have. Another is diabetes. While mine is controlled, Dr.Wegner pointed out to me that genetics is another risk factor -- and another test showed that I have a genetic predisposition to diabetes.

Dr. Wegner made two more suggestions. "Typically people in your age category often have elevated calcium scores that could affect your level," he told me. So my calcium score needs to be tested -- and this is now on the list of tests I will ask my primary care physician to give me the next time I see him.

Now I also need be tested for my small dense LDL, using any one of the three tests on the market, Dr. Wegner said. I've wanted to get this test for a long time, and now I have a real incentive to get it.

Perhaps you now have an incentive to get the Lp-PLA2 test. If so, you can read more about it here.