Blood Test Approved That Predicts Coronary Heart Disease Risk

The test works by measuring the activity of lipoprotein-associated phospholipase A2 (Lp-PLA2), an enzyme that is an indicator of vascular inflammation, in a blood sample. Vascular inflammation is a sign of plaque accumulation in the arteries, and this build-up of plaque can clog the arteries and cause coronary heart disease.

According to the US Food and Drug Administration (FDA; Silver Springs, MD, USA), the test has been cleared for use in both men and women with no history of heart disease, but studies have shown it is more accurate in predicting coronary heart disease risk (CHD) in women. Patients with Lp-PLA2 activity over 225 nmol/min/mL in their blood are deemed high risk of a CHD event, such as a heart attack or stroke. Patients with Lp-PLA2 activity below 225 nmol/min/mL are classed as lower risk for a CHD event.

The diaDexus PLAC Test for Lp-PLA2 (diaDexus; South San Francisco, CA, USA) is a sandwich enzyme immunoassay that uses two highly specific monoclonal antibodies for the direct measurement of Lp-PLA2 concentration in human plasma and serum. The FDA in their review included the PLAC Test for Lp-PLA2 Activity Validation Study, in which the test was administered on 4,598 participants aged 45 to 92 years who had no history of CHD. Of these participants, 58.3% were women and 41.5% were black. The study scientists followed the participants for an average of 5.3 years, during which time they recorded the occurrence of CHD events among each individual.

The results of the study revealed that 7% of participants with Lp-PLA2 activity higher than 225 nmol/min/mL experienced a CHD event, compared with only 3.3% of participants with Lp-PLA2 activity lower than 225 nmol/min/mL. On analyzing the team's data by subgroups, the FDA found that the rate of CHD events was much higher among African American women whose Lp-PLA2 activity levels were higher than 225 nmol/min/mL, compared with other subgroups with similar Lp-PLA2 activity. CHD events were also found to be more common among women with Lp-PLA2 activity levels over 225 nmol/min/mL than men with such levels.

Alberto Gutierrez, PhD, Director of FDA’s Office of In Vitro Diagnostics, said, “A cardiac test that helps better predict future CHD risk in women, and especially African American women, may help health care professionals identify these patients before they experience a serious CHD event, like a heart attack. We hope the clearance of this test will improve preventative care and reduce CHD-related mortality and morbidity in these patients.”

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US Food and Drug Administration
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