Heart-Risk Test Approved

Doctors are getting a new blood test to help predict which people with low cholesterol are at risk for heart disease.

The Food and Drug Administration approved the PLAC test Friday. It works by measuring an enzyme active in the inflammatory process known as Lp-PLA2.

In a study, researchers tracked more than 1,300 middle-aged people for nine years to see which of them were most at risk for developing heart disease.

Of most interest were people considered at very low risk because they had normal levels of the so-called bad cholesterol, or LDL cholesterol.

When those low-cholesterol patients had high levels of Lp-PLA2, however, they were twice as likely to develop heart disease, said lead researcher Dr. Christie Ballantyne of Baylor College of Medicine. Add another measure of risk -- a separate inflammatory protein called C-reactive protein -- to a high Lp-PLA2 level, and the risk of heart disease tripled, he said.

Between one-third and one-half of heart attacks occur in those without high cholesterol, so scientists have long sought ways to find which of those people were at risk.

The test is made by diaDexus Inc. of San Francisco, which said it would be priced competitively with testing for C-reactive protein, which costs roughly $16.