Discrepancy between myocardial perfusion and fatty acid metabolism following acute myocardial infarction for evaluating the dysfunctional viable myocardium

Abstract

Objective: Following acute myocardial infarction (AMI) the area of myocardial perfusion and metabolism mismatch is designated as dysfunctional viable myocardium. (123)I-beta-methyl iodophenyl pentadecanoic acid (BMIPP) is clinically very useful for evaluating myocardial fatty acid metabolism, and (99)mTc-Tetrofosmin (TF) is a widely used tracer for myocardial perfusion. This study was designed to evaluate the degree of discrepancy between BMIPP and TF at the subacute state of AMI.

Methods: Fifty-two patients (aged 59 ± 10 years; mean 46 years) with AMI were enrolled, and all of them underwent percutaneous coronary intervention (PCI). Patients were classified according to ST-T change and PCI timing. (123)I-beta-methyl iodophenyl pentadecanoic acid and TF cardiac scintigraphy were performed on 7 ± 3.5 days of admission using a dual headed gamma camera. Perfusion and fatty acid metabolism defect were scored on a 17 segments model.

Results: The mean BMIPP defect score on early and delayed images were 16.67 ± 10.19 and 16.25 ± 10.40, respectively. The mean TF defect score was 10 ± 7.69. Defect score of BMIPP was significantly higher than that of the TF (P < 0.0001; 95% CI 4.32-7.02), and there was a strong correlation between perfusion and metabolism defect score (r = 0.89, P < 0.00001). Forty-seven (90%) patients showed mismatched defect (BMIPP > TF), and 5 (10%) patients showed matched defect (BMIPP = TF). Mismatched defect score (MMDS) was significantly higher in patients with ST-segment elevation myocardial infarction (STEMI) than that of non-ST-segment elevation myocardial infarction (NSTEMI) (P < 0.041; 95% CI 0.11-5.19).

Conclusion: At the subacute state of AMI, most of the patients showed perfusion-metabolism mismatch, which represents the dysfunctional viable myocardium, and patients with STEMI showed higher mismatch.