Scintigraphic assessment of silent myocardial ischaemia after early infarction using myocardial SPET imaging with 201Tl and 123I-MIBG.
To test the hypothesis that myocardial sympathetic denervation reflects silent myocardial ischaemia early after infarction, 12 patients with myocardial infarction but without post-infarction angina pectoris underwent single photon emission tomography (SPET) at rest with 201Tl and 123I-metaiodobenzylguanidine (MIBG) shortly after and 3 months after infarction. Short-axis SPET images at the basal, mid-ventricular and apical portions of the left ventricle were selected, and each short-axis image was divided into eight segments. Tracer uptake in each of the 24 segments was scored using a 4-point scale. The total score in each segment was calculated as the defect score for each image, and the difference between the total defect score for the 201Tl and 123I-MIBG images was calculated as the delta defect score. All 12 patients underwent exercise stress 201Tl scintigraphy 1 month after infarction, and they were divided into two groups: those patients with (Group A, n = 7) and those patients without (Group B, n = 5) transient perfusion defects in the peri-infarcted region without chest pain. For the 123I-MIBG defect score, a marked reduction at 3 months was observed in Group A (24 +/- 12 vs 13 +/- 6; P < 0.01), whereas the defect score remained unchanged in Group B (25 +/- 7 vs 23 +/- 8; N.S.). The delta defect score was significantly reduced in Group A (10 +/- 5 vs 6 +/- 4; P < 0.05), whereas it remained unchanged in Group B. The 123I-MIBG defect score early after infarction was higher than the exercise-induced 201Tl defect score (24 +/- 12 vs 20 +/- 9; P < 0.01), whereas at 3 months post-infarction it was lower than the exercise-induced 201Tl defect score (13 +/- 6 vs 20 +/- 9; P < 0.05). Moreover, effort chest pain during daily activities was noted in 5 of the 7 (71%) patients in Group A within 3 months post-infarction. The results of this study suggest that viable but denervated myocardium (mismatched 123I-MIBG defects) is present in peri-infarcted regions, and that myocardial sensory nervous disturbance, which may co-exist with sympathetic nervous denervation, may induce silent myocardial ischaemia in patients with myocardial infarction.
Shimonagata
T
T
Department of Radiology, National Cardiovascular Centre, Osaka, Japan.
Ishida
Y
Y
Hayashida
K
K
Takamiya
M
M
Uehara
T
T
Nishimura
T
T
D019797:3-Iodobenzylguanidine; D016022:Case-Control Studies; D003287:Contrast Media; D005080:Exercise Test; D005260:Female; D005500:Follow-Up Studies; D006321:Heart / Q000000981:diagnostic imaging / Q000294:innervation; D006801:Humans; D007457:Iodine Radioisotopes; D007462:Iodobenzenes; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000150:complications / Q000000981:diagnostic imaging*; D017202:Myocardial Ischemia / Q000000981:diagnostic imaging* / Q000209:etiology / Q000503:physiopathology; D013564:Sympathetic Nervous System / Q000503:physiopathology; D013794:Thallium Radioisotopes; D013997:Time Factors; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*
D003287:Contrast Media; D007457:Iodine Radioisotopes; D007462:Iodobenzenes; D013794:Thallium Radioisotopes; D019797:3-Iodobenzylguanidine