New Test to Predict Heart Disease

Last Editorial Review: 7/21/2003

There are many tests that are associated with ("predict") heart disease. With each test there are important questions that must be answered before the test's true value is known. For example, how well does it perform? (Does it select a high proportion of patients with heart disease while excluding a high proportion of people without heart disease?) Is it a strong predictor or a weak one? Does its predictive value overlap with other tests making its value less? Because of the complexities of answering such questions, physiological testing for existing heart disease (e.g., stress testing) and monitoring the progression of heart disease will continue to have an important role in the detection of heart disease.

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Jay W. Marks, M.D.
Medical & Pharmacy Editor,

FDA Clears New Lab Test to Help Predict Those at Risk of Coronary Heart Disease

The Food and Drug Administration (FDA) cleared for marketing a new laboratory blood test that will increase the ability of doctors to predict the risk of coronary heart disease (CHD).

The test, called PLAC, works by measuring an enzyme called lipoprotein-associated phospholipase A2. This enzyme is made by a type of white blood cell called a macrophage. Macrophages make more of this enzyme and release it into the blood when a person has CHD.

FDA cleared the test based on results of a study of more than 1,348 patients. The study was a part of a large multi-center epidemiologic study sponsored by the National Heart, Lung, and Blood Institute. Patients were free from CHD at the start of the study and were followed for the development of disease for nine years. The greatest increased risk was found in subjects with the highest PLAC test results and LDL cholesterol levels lower than 130mg/dL.

The PLAC test is not a stand-alone test for predicting CHD. The test provides supportive information when used with clinical evaluation and other tools for patient risk assessment. An elevated PLAC test result with an LDL-cholesterol level of less than 130 mg/dL gives doctors increased confidence that patients have two to three times the risk of having coronary heart disease when compared with patients having lower PLAC test results.

Some 7 million Americans suffer from CHD, the most common form of heart disease. This type of heart disease is caused by a narrowing of the coronary arteries that feed the heart. CHD is the number one killer of both men and women in the U.S. Each year, more than 500,000 Americans die of heart attacks caused by CHD.

The PLAC test is manufactured by diaDexus, Inc. of San Francisco, Calif.

Source: FDA Talk Paper # T03-53, July 18, 2003 (

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