Measuring plasma levels of myeloperoxidase can help predict the immediate risk of myocardial infarction (MI) in patients with chest pain, according to new research. The test also helps predict the risk of MI in the ensuing 6 months.

Myeloperoxidase, a product of activated leukocytes, is elevated in the presence of unstable atherosclerotic plaque. Unlike troponin T, which indicates necrosis, myeloperoxidase indicates arterial inflammation.

Researchers evaluated myeloperoxidase levels in 604 people who arrived at an emergency department within 24 hours of the onset of chest pain of suspected cardiac origin. The median myeloperoxidase levels were significantly higher in patients who had an MI within 16 hours than in those who didn't. These findings held true even for patients with normal troponin T levels. Combined testing of myeloperoxidase and troponin T predicted over 84% of subsequent cardiac events, compared with 58% with troponin testing alone.

Researchers expect an inexpensive commercial test incorporating myeloperoxidase testing to be available soon.

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