運動負荷~(201)Tl心筋spECT定量法による陳旧性心筋梗塞の経皮的冠動脈形成術後の心機能改善予測

摘要

[目的]運動負荷~(201)T1心筋spECTおよび心プールシンチグラフィの定量指標を経皮的冠動脈形成術前後で比較し,左室駆出率の改善予測を試みた. 〔方法〕経皮的冠動脈形成術3~6か月後に冠動脈造影検査を行った陳旧性心筋梗塞患者28例を対象とした. 〔結果〕術3~6か月後に再狭窄を認めない群では,正常部位に対する形成冠動脈灌流域の~(201)Tlのカウント比は,初期像では術1週間後·3~6か月後共に有意に改善し(それぞれp<0.05, p<0.01),後期像では改善傾向を認めた.同群での術3~6月後の左室駆出率の変化量は,術前のSPECT初期像および後期像のカウント比と有意な相関を認めた(それぞれr=0.652, r=0.645).重回帰分析では,術前の後期像カウント比と左室駆出率が,術後の左室駆出率の変化量の説明変数として選択された(重相関係数=0.776). 〔結論〕術前の~(201)T1心筋spECT後期像カウント比と,心プールシンチグラフィより求めた左室駆出率により,術後の左室駆出率の改善を予測できることが示唆された.[Purpose] We examined whether the improvement of left ventricular function after percutaneous trans-luminal coronary angioplasty (PTCA) in patients with one diseased vessel can be predicted by the quantitative indices from exercise stress ~(201)T1 single photon emission computed tomography (SPECT) and radio-nuclide angiography (RNA) before PTCA.[Methods] Exercise stress ~(201)T1 myocardial SPECT and RNA were performed before and after PTCA in 28 patients with old myocardial infarction (OMI). The patients were divided into two groups according to the results of coronary angiogram performed at 3 to 6 months after PTCA; patency was confirmed in 22 patients (Group P) and restenosis was observed in the remaining 6 patients (Group S).[Results] In Group P, the count ratios defined as ~(201)T1 uptake in the PTCA region divided by the uptake in the normal region were significantly improved at 1 week and 3 to 6 months after PTCA in the initial image.~(201)T1 washout rates in the normal regions were significantly increased at 1 week after PTCA in Group S, and these rates in the PTCA regions were significantly increased at 1 week after PTCA in Group P.Left ventricular ejection fractions (LVEF) obtained from RNA were significantly improved 1 week and 3 to 6 months after PTCA in Group P.The changes of LVEF between pre-PTCA and 3 to 6 months after PTCA (DELTA LVEF) were significantly correlated with the count ratios of both initial and delayed SPECT images in Group P (r = 0.652; p<0.01, r = 0.645; p<0.01 respectively).From the multiple regression analysis using step-wise methods, the count ratio in delayed image and the LVEF before PTCA were selected as independent predictive variables for DELTA LVEF (multiple correlation coefficient=0.776).[Conclusion] Thus, the improvement of LVEF after PTCA may be predictable by the count ratio in the delayed SPECT image and LVEF before PTCA when the treated vessel is persistently patent.