LpPLA2 may be reliable predictor of CAD in women

LpPLA2 was differentially predictive of angiographic CAD and CAD death across glycemic and clinical diabetes mellitus categories.

March 2006

DALLAS — Lipoprotein-associated phospholipase A₂ was found to be an independent predictor of coronary artery disease in women, particularly women older than age 65, in the Intermountain Heart Collaborative Study.

Jeffrey Anderson, MD, professor of internal medicine at the University of Utah, said that LpPLA₂ was more strongly predictive of CAD risk than C-reactive protein in postmenopausal women. High LpPLA₂ was predictive for CAD among women younger than 65 (OR=2.26, P=.04) and among women older than 65 (OR=2.68, P=.001).

Results of this study indicate that if women have elevated levels of both CRP and LpPLA₂, they may be at very high risk for CAD, Anderson told Cardiology Today.

PLAC test used

For the study, researchers measured LpPLA₂ with the PLAC test (diaDexus Inc.) in samples donated by 1,493 adults enrolled in the registry. The results were divided at the median into higher and lower LpPLA₂ groups.

All patients (average age 63, 70% men) underwent coronary angiography between 1996 and 1998 as a diagnostic procedure for CAD. Although there was no significant interaction found between LpPLA₂ and increased CAD risk for sex alone or age alone, researchers identified a significant three-way interaction between sex and age on CAD risk.

For women, a high LpPLA₂ level was predictive for CAD at both younger and older ages. For men, a high LpPLA₂ was predictive for those under age 65 but was not significantly predictive for men older than age 65.

“In contrast, CRP was only marginally predictive in older women but retained predictive value in older men (P=.02),” the researchers reported at the American Heart Association Scientific Sessions 2005.

Patients with diabetes

Using the same patients, researchers also examined whether the predictive value of the enzyme differs in patients by glycemic or diabetic status. For this analysis, patients were categorized by fasting glycemic status as normal (<100 mg/dL), intermediate (100 to 125 mg/dL), or high ( >126 mg/dL), or by a clinical diagnosis of diabetes mellitus.

They were followed for an average of 6.8 years to determine the incidence of CAD mortality.

Investigators reported that LpPLA₂ stratified by glucose levels predicted CAD in intermediate fasting glycemic status and diabetes. “LpPLA₂ was differentially predictive of angiographic CAD and CAD death across glycemic and clinical diabetes mellitus categories,” they said.

“Predictive ability for CAD was not enhanced in patients with hyperglycemia, whereas predictive value for CAD death was limited to those with a clinical diagnosis of diabetes mellitus. These intriguing results should be prospectively validated in larger, independent populations of patients spanning the spectrum of [fasting glycemic status],” they said. – by Kathy Holliman

For more information:

• Thomas H, Horne BD, Carquist JF, et al. Sex and age-related differences in levels of lipoprotein-associated phospholipase A₂. #3601.
• Thomas H, Horne BD, Anderson JL, et al. Lipoprotein-associated phospholipase A₂ may differentially predict the presence of angiographic coronary artery disease and coronary death across glycemic categories. #3654. Both presented at the American Heart Association Scientific Sessions 2005. Nov. 13-16, 2005. Dallas.