[Clinical significance of exercise-induced ST segment depression in patients with lateral myocardial infarction involving the left circumflex artery: evaluation by exercise 99mTc-MIBI myocardial scintigraphy].
OBJECTIVE
The aim of this study is to clarify the causes of exercise-induced ST-segment depression in patients with broad lateral old myocardial infraction involving LCX (LCX-OMI) without ischemia on exercise scintigraphy.


METHODS
Twenty one patients (M/F = 11/10, age = 62 +/- 19 years) with myocardial infraction involving LCX (LCX-MI), but without fill-in on exercise and rest MIBI quantitative gated SPECT (QGS), were selected. They were divided into two groups of Group ST(+) (n = 11, with significant ST depression (max -2.8 +/- 0.4 mm), Group ST(-) (n = 10) without ST depression. On 20 SPECT segments of both exercise and rest SPECT, we scored uptake score as DS (0 = normal to 3 = defect) and wall motion as WMS (0 = normal to -5 = dyskinesis) and summed DS (TDS) and WMS (TWMS) in LCX region, furthermore, calculated the difference of TWMS (delta TWMS [exercise-rest]), end diastolic volume (EDV) and ejection fraction (EF) during exercise were compared between the two groups.


RESULTS
Group ST(+) showed significantly (p < 0.01) lower EF (35.4 +/- 9.2% vs. 60.2 +/- 6.2%), larger EDV (146 +/- 53 ml vs. 93 +/- 15 ml), higher TDS (5 vs. 7 +/- 3), lower TWMS (-25 +/- 9 vs. -6 +/- 5), furthermore lower delta TWMS (-6.9 +/- 4.0 vs. -2.0 +/- 0.8) than Group ST(-).


CONCLUSIONS
Exercise-induced significant ST depression in V2-4 without ischema in LCX-MI was observed in patients with broad LCX-MI, low EF, and was related to impaired wall motion in LCX region. ST depression in V2-4 was considered to appear as miller image of ST elevation at postero-inferior wall due to disturbed wall motion on exercise.
Tsurugaya
Hideki
H
Division of Cardiology, Gunma Prefectural Cardiovascular Center.
Toyama
Takuji
T
Isobe
Naoki
N
Hoshizaki
Hiroshi
H
Oshima
Shigeru
S
Taniguchi
Koichi
K
D000328:Adult; D000368:Aged; D004562:Electrocardiography; D005080:Exercise Test; D005260:Female; D015637:Gated Blood-Pool Imaging / Q000379:methods; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000000981:diagnostic imaging* / Q000503:physiopathology; D019275:Radiopharmaceuticals; D012984:Software; D017256:Technetium Tc 99m Sestamibi; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods; D016277:Ventricular Function, Left
D019275:Radiopharmaceuticals; D017256:Technetium Tc 99m Sestamibi