虚血性心疾患における運動負荷心電図ならびに運動負荷心筋シンチグラムの有用性と限界—とくに1枝障害例を中心に

The clinical value and limitation of exercise electrocardiography and exercise thallium-201 myocardial scintigraphy in the diagnosis of coronary artery disease, with special reference to single vessel disease

　近年トレッドミル運動負荷心電図試験（以下負荷心電図）ならびに²⁰¹Tl運動負荷心筋シンチグラム検査（以下負荷心筋シンチ）は，非侵襲的に冠動脈病変を推定する有力な検査法として臨床上広く応用されている^1〜3）。しかしこれら運動負荷試験を行うにあたって，その感受性ならびに特異性を常に念願においておかねばならない。本邦において負荷心電図ならびに負荷心筋シンチと冠動脈病変とを対比検討した報告は少ない^4,5）。

　我々は，虚血性心疾患を疑われた症例で心筋梗塞を伴わない40例について負荷心電図，負荷心筋シンチとともに冠動脈造影（以下CAG）を施行し，その比較検討を行うとともに，特に1枝障害例を中心にその特異性ならびに感受性を検討し，あわせてfalse negative,falsepositive例についても若干の考察を加えた。

The clinical value and limitation of exercise electrocardiography and exercise thallium-201 myo-cardial scintigraphy were studied in 40 patients with no previous history of myocardial infarction. Coronary angiography was performed on all the patients. Compared with thallium-201 myocardial scintigraphy, treadmill exercise electrocardiography showed greater sensitivity (84% versus 63%) in diagnosing coronary stenosis of more than 50%. In patients with single vessel disease, the results of sensitivities were similar (75% to 65%). However, the specificity of thallium-201 myocardial scinti-graphy was higher than that of exercise electrocar-diography (100% compared to 63%). Nine pa-tients with evidence of significant lesions using coro-nary angiography, showed normal conditions using exercise electrocardiography and thallium myocar-dial scintigraphy examinations as well. All these patients had a history of chest pain, and 4 of them experienced chest pain during exercise. In cases with false negative exercise tests, the clinical sym-ptoms and exercise-induced chest pain seem to be important diagnostic signs when evaluating patients with coronary artery disease. In 15 patients with isolated single vessel coronary artery disease (more than 75% stenosis of luminal diameter in only one vessel), the site of ST segment depression did not coincide with the stenotic lesion. The site of revers-ible perfusion defect on thallium-201 myocardial scintigraphy did, however, coincide with the site of myocardial ishemia and the stenotic lesion in most cases.