Researchers demonstrated that Lp-PLA2 (lipoprotein-associated phospholipase A2) independently predicts both the severity of obstructive coronary artery disease at the time of coronary angiography and future cardiovascular problems, including death. The study was undertaken by diaDexus and LDS Hospital cardiology researchers.
“These data further cement the relationship between lipids and inflammation,” notes John F. Carlquist, Ph.D., of the cardiovascular department, LDS Hospital, University of Utah. “Aside from advancing our understanding of the pathologic processes in coronary disease, Lp-PLA2 adds a quantitative measure to cardiovascular risk assessment.”
The study was published in the November 2006 issue of the American Heart Journal. Lp-PLA2, a cardiovascular-specific inflammatory biomarker, was measured using the PLAC® test, developed by diaDexus. The predictive ability of Lp-PLA2 was independent of traditional risk factors, C-reactive protein (CRP, a systemic inflammatory biomarker), and statin and antihypertensive medication use.
The study used blood samples collected from 1,493 patients enrolled in the Intermountain Heart Collaborative Study. Levels of both Lp-PLA2 and CRP were measured in all patients. Patients also underwent coronary angiography for diagnosis of possible coronary artery disease. Patients’ Lp-PLA2 and CRP levels were compared with their angiograms to determine if the levels were predictive of existing heart disease. Patients then were followed for about seven years to see if the measured Lp-PLA2 and CRP levels were predictive of future cardiovascular problems, including heart attack, stroke, and death.
“In this large, prospectively enrolled group of patients being assessed and treated for coronary artery disease, Lp-PLA2 was confirmed to be an independent risk factor, improving risk stratification for patients receiving coronary angiography,” says Robert Wolfert, Ph.D., executive vp of diagnostics at diaDexus. “One of the strengths of this biomarker is its specificity to cardiovascular inflammation. We believe that the value of Lp-PLA2 lies in its ability to help identify patients who should be targeted with the most aggressive treatment.”
Wolfert explains that Lp-PLA2 associates in the blood with low-density lipoprotein. Lp-PLA2 is carried to the walls of coronary arteries with LDL, where it can activate an inflammatory response, promoting atherosclerosis. As a result, Lp-PLA2 serves as a specific indicator of vascular inflammation and, therefore, a more specific predictor of coronary artery disease than CRP.