運動負荷1時間後に認める一過性の左心機能障害:99mTc-心筋血流製剤心拍同期SPECTによる検討

摘要

運動負荷1時間後でも,運動負荷により生じた左心機能不全(PSD)が持続しているか,心拍同期SPECTで検討した.対象は152例で,運動負荷99mTc-Tetrofosmin心筋シンチグラフィを一日法(負荷時·安静時)で施行した.血流画像で欠損のseverityを求め,負荷時および安静時所見より対象は4群:正常(n=59),梗塞(n=65),軽度虚血(n=13)および高度虚血(n=15)に区分した.心拍同期SPECTより左室拡張末期容積,収縮末期容積(ESV)および駆出率(EF)は計測され, PSDは1)安静時EF一負荷後EF>=5%および2)負荷後ESV一安静時ESV>=5mlであるとした. PSDの頻度は正常3.4%,梗塞9.2%,軽度虚血23.1%および高度虚血40%で,高度虚血は正常および梗塞より高頻度であった(p<0.01). PSDは運動負荷1時間後でも存在し,高度虚血群で高頻度であった.It has been reported that quantitative gated SPECT (QGS) has revealed post-stress dysfunction of the left ventricle (LV) 30 minutes after a stress test. The purpose of this study was to determine whether post-stress dysfunction of LV is still present one hour after an exercise stress test. The subjects comprised 152 patients (124 males and 28 females, mean age 59+ 10 years). Exercise stress myocardial scintigraphy was performed using a one-day, stress and rest protocol. ~(99m)Tc labeled myocardial perfusion tracer, tetro-fosmin, 370 MBq was injected at the end-point of a supine ergometer stress test for stress imaging. ECG gated SPECT was carried out 1 hour after injection. Three hours later, 740 MBq to 1100 MBq of ~(99m)Tc labeled myocardial perfusion tracer was injected for rest imaging. ECG gated SPECT was again performed 1 hour after injection. We divided the subjects into four groups according to the severity score of defects on the stress image and the presence or absence of fill-in; normal (NOR, n=59), myocardial infarct (MI, n= 65), small ischemia (S-IS, n= 13) and large ischemia (L-IS, n = 15). Post-stress dysfunction is defined according to two criteria: 1) rest LVEF -post-stress LVEF>=5% and 2) post-stress ESV-rest ESV>=5 ml. The frequency of post-stress dysfunction was 3.4%, 9.1%, 23.1% and 40% in NOR, MI, S-IS and L-IS, respectively. Post-stress LV dysfunction was found to be more frequent in the large ischemia group. In conclusion, post-stress dysfunction was present 1 hour after the stress test and was more frequent in the large ischemia group.