An international team compared measurements of oxidized low-density lipoprotein from patients with acute heart disease including myocardial infarction with measurements from subjects who had stable heart disease or were healthy. Oxidized low-density lipoprotein cholesterol is recognized as a critical factor in atherosclerosis and the rupture of arterial plaques. Previous laboratory and animal studies have examined the same plaque component, but the current study applied new tests to its human participants.

"There's a whole body of experimental data in animal models, but now these measures are finally being applied in patient populations," said Sotirios Tsimikas, M.D., lead author. “With this study we've actually been able to measure these oxidized lipids in the blood. The link between what we measure in the blood and what's in the vessel wall is that we think some of these lipids are actually coming out of the vessel wall when the plaques become unstable and become disrupted."

In order to see if such measurements were associated with acute heart conditions, the researchers ran a series of blood tests over a period of 7 months on 8 survivors of myocardial infarction, 15 patients with unstable angina, 17 patients with stable coronary artery disease who had not had any new problems for at least a year, 8 patients who had normal coronary arteries based on angiography, and 18 healthy controls. The current study is the first to document the rise and fall of a blood marker over an extended period in patients who have had a myocardial infarction.

"What we found was that the markers were elevated only in patients that had an acute coronary syndrome, either unstable angina or myocardial infarction," Tsimikas said. In patients with myocardial infarction, the levels of oxidized low-density lipoprotein cholesterol rose, then leveled off and subsided in the following months. In healthy individuals or patients with stable disease, the marker levels remained unchanged. Although standard measures of low-density and high-density lipoprotein cholesterol offer general information about risk over a long time period, the new tests used in this study may someday offer more specific and timely information about risk.

"This is a very small study, but since these markers change only in people who have acute coronary syndromes, we may be able to apply them before people have events and maybe predict risk," Tsimikas said. The researchers plan to study their new blood test in a larger group of subjects to see if the markers predict which individuals are likely to develop an acute coronary syndrome.