Yamagishi T, Matsuda Y, Satoh A, Ichioka T, Furutani Y, Haraguchi M, Ozaki M, Kusukawa R, Maeda J, Nakatsuka M
Second Department of Internal Medicine, Yamaguchi University School of Medicine, Ube.
Kaku Igaku. 1991 Mar;28(3):261-9.
To assess the reliability of the exercise ECG in detecting silent ischemia, ECG results were compared with those of stress-redistribution thallium-201 single-photon emission computed tomography (SPECT) in 116 patients with prior myocardial infarction and in 20 normal subjects used as a control. The LV was divided into 20 segmental images, which were scored blindly on a 5-point scale. The redistribution score was defined as thallium defect score of exercise subtracted by that of redistribution image and was used as a measure of amount of ischemic but viable myocardium. The upper limit of normal redistribution score (= 4.32) was defined as mean +2 standard deviations derived from 20 normal subjects. Of 116 patients, 47 had the redistribution score above the normal range. Twenty-five (53%) of the 47 patients showed positive ECG response. Fourteen (20%) of the 69 patients, who had the normal redistribution score, showed positive ECG response. Thus, the ECG response had a sensitivity of 53% and a specificity of 80% in detecting transient ischemia. Furthermore, the 116 patients were subdivided into 4 groups according to the presence or absence of chest pain and ECG change during exercise. Fourteen patients showed both chest pain and ECG change and all these patients had the redistribution score above the normal range. Twenty-five patients showed ECG change without chest pain and 11 (44%) of the 25 patients had the abnormal redistribution. Three (43%) of 7 patients who showed chest pain without ECG change had the abnormal redistribution score. Of 70 patients who had neither chest pain nor ECG change, 19 (27%) had the redistribution score above the normal range. Thus, limitations exist in detecting silent ischemia by ECG in patients with a prior myocardial infarction, because the ECG response to the exercise test may have a low degree of sensitivity and a high degree of false positive and false negative results in detecting silent ischemia.
为评估运动心电图检测无症状性心肌缺血的可靠性，对116例既往有心肌梗死的患者以及20例作为对照的正常受试者进行了研究，将运动心电图结果与静息-再分布铊-201单光子发射计算机断层扫描（SPECT）结果进行比较。左心室被分为20个节段图像，并采用5分制进行盲法评分。再分布评分定义为运动时铊缺损评分减去再分布图像的铊缺损评分，用作缺血但存活心肌量的衡量指标。正常再分布评分的上限（=4.32）定义为20例正常受试者的均值加2个标准差。116例患者中，47例的再分布评分高于正常范围。这47例患者中有25例（53%）心电图反应呈阳性。再分布评分正常的69例患者中有14例（20%）心电图反应呈阳性。因此，心电图反应检测短暂性心肌缺血的敏感性为53%，特异性为80%。此外，根据运动期间是否存在胸痛和心电图变化，将116例患者分为4组。14例患者既有胸痛又有心电图变化，所有这些患者的再分布评分均高于正常范围。25例患者有心电图变化但无胸痛，其中11例（44%）再分布异常。7例有胸痛但无心电图变化的患者中有3例（43%）再分布评分异常。70例既无胸痛也无心电图变化的患者中，19例（27%）的再分布评分高于正常范围。因此，既往有心肌梗死的患者通过心电图检测无症状性心肌缺血存在局限性，因为运动试验的心电图反应在检测无症状性心肌缺血时可能敏感性较低，假阳性和假阴性结果的发生率较高。
