Non-Q-wave myocardial infarction: impaired myocardial energy metabolism in regions with reduced 99mTc-MIBI accumulation.
Reduced regional technetium-99m methoxyisobutylisonitrile (99mTc-MIBI) accumulation in patients with chronic non-Q-wave infarction (NQWI) but without significant coronary artery stenosis indicates non-transmural damage of the myocardial wall. The aim of this study was to characterise cardiac energy metabolism after NQWI using phosphorus-31 magnetic resonance spectroscopy (31P-MRS) and to compare the biochemical remodelling with changes in regional 99mTc-MIBI uptake and with morphological and functional parameters assessed by magnetic resonance imaging (MRI). Fifteen patients with a history of NQWI, exclusion of significant coronary artery stenosis (<50% diameter stenosis) and hypokinesia of the anterior wall (group A) were examined with 31P-MRS to study the effects of NQWI on myocardial energy metabolism. Spectroscopic measurements were performed in the infarct-related myocardial region. Corresponding gradient-echo MR images and myocardial 99mTc-MIBI single-photon emission tomography images were acquired for exact localisation of the infarct region. All examinations were performed at rest under anti-ischaemic medication. Data were compared with those of patients in whom coronary artery disease had been excluded by angiography (group B, n=10). All patients of group A displayed anterior wall hypokinesia in the infarcted area on both ventriculography and MRI, with a reduced myocardial accumulation of 99mTc-MIBI (66.3%+/-11.8% vs 95.6%+/-2.2% in group B). The mean wall thickness during the complete cardiac cycle (9.5+/-1.8 mm vs 13.1+/-1.1 mm in group B, P<0.001), the systolic wall thickening (2.6+/-1.4 mm vs 5.8+/-1.5 mm in group B, P<0.01) and the phosphocreatine/adenosine triphosphate ratio (1.12+/-0.22 vs 1.74+/-0.23 in group B, P<0.01) in the hypokinetic area were all significantly reduced. It is concluded that persisting hypokinetic myocardium after NQWI combined with reduced myocellular uptake of 99mTc-MIBI displays a reduced PCr/ATP ratio. Our results indicate that morphological remodelling after NQWI is accompanied by fundamental changes in cardiac energy metabolism.
Moka
D
D
Department of Nuclear Medicine, University of Cologne, Köln, Germany.
Baer
F M
FM
Theissen
P
P
Schneider
C A
CA
Dietlein
M
M
Erdmann
E
E
Schicha
H
H
D000255:Adenosine Triphosphate / Q000378:metabolism; D000368:Aged; D000369:Aged, 80 and over; D004562:Electrocardiography; D004734:Energy Metabolism; D005260:Female; D006321:Heart / Q000000981:diagnostic imaging; D006801:Humans; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism* / Q000473:pathology; D010725:Phosphocreatine / Q000378:metabolism; D019275:Radiopharmaceuticals; D017256:Technetium Tc 99m Sestamibi; D015899:Tomography, Emission-Computed, Single-Photon
D019275:Radiopharmaceuticals; D010725:Phosphocreatine; D000255:Adenosine Triphosphate; D017256:Technetium Tc 99m Sestamibi