False inferoposterior fatty acid uptake rest defects in patients with first anterior myocardial infarction

Fatty acid scintigraphy is an interesting new technique for assessing the extent of myocardial infarction. We studied 19 patients with electrocardiographically verified first anterior myocardial infarction using radioiodinated phenylpentadecanoic acid and single photon emission computed tomography (SPECT). Besides the expected lesions in the territory of the left ascending coronary artery, a total of nine patients (47%) had severe (uptake < 50% of maximum) defects in the presumptive territory of the right coronary artery at rest. A link between the size of anterior injury and the occurrence of inferoposterior lesions was established. Over 20% paradoxical relative filling-in was seen in four of these inferoposterior defects in the subsequent exercise imaging, but only once anteriorly. Exercise-induced ischaemia (reduction in relative uptake > 20%) was demonstrated in 11 cases (58%). Ischaemia occurred most frequently in patients with small infarcts, and it did not coincide with the reversed redistribution. We conclude that the inferoposterior rest defects are unlikely to have been caused by technical artefacts or local injury, and should perhaps rather be linked with general strain in the left ventricle during the early phase of myocardial remodeling after anterior infarction. In any case, our results indicate that shortly after infarction myocardial viability should be evaluated very cautiously.