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Unbound free fatty acid concentrations are increased in cardiac ischemia


Monitoring increased plasma unbound free fatty acid (FFAu) concentrations has been proposed as a biomarker for myocardial ischemia. In the current study, 30 acute coronary syndrome (ACS) patients presenting in the emergency department, with chest pain within 12 h of onset, were clinically evaluated along with serial cardiac troponin I (cTnI) and FFAu measurements.

Increased FFAu were found in 28 of 30 (93%) of ACS patients, ranging from 2.0 to 430 nM. For the nine ACS patients with myocardial infarction (MI), FFAu levels were increased at presentation for all (100%). In contrast, cTnI was increased in only 9 of 30 (30%) patients, mean 0.7 μg/L, and in only 2 of 9 (22%) MI patients, mean 1.3 μg/L. During the 24 h following admission, cTnI increased in all 9 MI patients. FFAu concentrations increased in every sample in which cTnI increased.

Our findings suggest that FFAu is increased in ischemia regardless of the presence or absence of myocardial necrosis, as reflected by increased or normal cTnI, respectively.


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Correspondence to Fred S. Apple.

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Apple, F.S., Kleinfeld, A.M. & Adams, J. Unbound free fatty acid concentrations are increased in cardiac ischemia. Clin Proteom 1, 41–44 (2004).

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Key Words

  • Unbound free fatty acids
  • ischemia
  • myocardium
  • cardiac troponin