Lp-PLA2 Activity Test Helps Predict Risk of Heart Disease, Especially in Women

The U.S. Food and Drug Administration (FDA) recently approved a test for lipoprotein-associated phospholipase A2 (Lp-PLA2) activity that helps predict an individual's risk of future coronary heart disease (CHD) events, such as heart attacks. It is intended to be used along with a clinical evaluation and cardiac risk assessment to help determine risk in people with no history of heart disease. It is particularly helpful in predicting risk in women, especially African American women.

The blood test measures the activity of the enzyme Lp-PLA2, a biological marker for vascular inflammation. The marker is associated with the presence of unstable plaque in arteries that is likely to break apart or rupture. Most heart attacks are caused by ruptured plaque and clots (thrombi) that cause blockages in the arteries that supply blood to the heart.

In 2007, the FDA approved a similar test that uses enzyme immunoassay to measure the amount rather than the activity of Lp-PLA2. In reviewing fresh data from the study on the newer LP-PLA2 activity test submitted by the test's manufacturer, the FDA found that the activity test is better at predicting risk for women, and in particular African American women, than for men.

Heart disease is the leading cause of death in women in the U.S., killing 1 in 3 annually, according to the American Heart Association. Almost 50,000 African American women die of CHD each year and only about one-third of African American women are aware that heart disease is their greatest risk. Heart disease affects each woman differently and the signs and symptoms for woman are different than for men.

"A cardiac test that helps better predict future CHD risk in women, and especially black women, may help health care professionals identify these patients before they experience a serious CHD event, like a heart attack," said Alberto Gutierrez, director of the Office of in Vitro Diagnostics and Radiological Health in the FDA's Center for Devices and Radiological Health. "We hope the clearance of this test will improve preventative care and reduce CHD-related mortality and morbidity in these patients."

Close to 4,600 people participated in the clinical trials to study the Lp-PLA2 activity test. Participant ages ranged from 45 to 92, and the trial was made up of 41.7% men and 58.3% women, and 41.5% African Americans and 58.5% Caucasians. Participants had no CHD at the start of the trial and were studied for an average of 5 years. The researchers found that trial participants with test results above a certain level had a CHD event rate of 7%, while patients with test results below that level had a CHD event rate of 3.3%. Notably, subgroup analysis by gender and race showed that African American women had the greatest increase in CHD events compared to other participants when results were higher than the defined level.

Though approved by the FDA, not all experts agree that evaluating CHD risk with the Lp-PLA2 activity test or other cardiac biomarkers such as hs-CRP is useful. It is unclear whether the newly approved test will be adopted into clinical practice or cardiac guidelines, or that it will affect how health practitioners will evaluate and treat their patients for CHD risk. Research likely will continue to examine the usefulness of this and other cardiac marker tests.