背景 低劑量 dobutamine 心臟超音波被證實為應用於評估首次罹患急性心肌梗塞病患之左心室心肌存活性的準確影像工具之一，但定，除了無法應用於已使用強心劑之病患及耗時的缺點外，dobutamine 用於急性心肌梗塞病患有引發進一步心肌缺氧之危險。即時造影劑超音波是評估微型血管灌流之利器。本研究之目的是想比較即時造影劑超音波和低劑量dobutamine 心臟超音波，用於評估首次罹患急性心肌梗塞病患無法收縮及收縮困難的左心室心肌之存活性。方法 共四十五位首次罹患急性心肌梗塞病患在胸痛發作後的一週內，進行二度空間心臟超音波，即時造影劑超音波之檢查，及低劑量 dobutamine 心臟超音波。四個月後所有病患予以追蹤二度空間心臟超音波，用以評估無法收縮及收縮困難的左心室心肌之存活性。結果 我們共分析 260 個收縮困難或無法收縮的心肌區域，經即時造影剖超音波檢查，呈現均勻分部或塊狀顯影之區域可用於預測左心室心肌存活的敏感度為81.4%，特異性為76.7%，準確度為79.4%，正向預測值81.8%為及負向預測值為75%，此準確性與低劑量dobutamine 心臟超音波不相上下(79.4% vs. 76.8%，p=0.52)，而即時造影劑超音波檢查有較高之敏感度(81.4% vs. 68.9%，p<0.005)，低劑量 dobutamine 心臟超音波有較高之特異性 (76.7% vs. 87.6%，p<0.01)。即時造影劑超音波檢查平均耗時較少(374±102 seconds vs.785±216 seconds，p<0.001)，且無任何併發症。而在 dobutamine 心臟超音檢查中，4.5%病人罹患頭痛及2.2%病患有胸悶之症狀(p<0.001)。結論 即時造影劑超音波雖然受到下壁或後壁“衰退現象”的限制，但仍可早期評估急性心肌梗塞病患之左心室心肌存活性，其準確性與低劑量 dobutaminc心臟超音波不相上下。同時，即時造影劑超音波可以更安全及省時的應用於早期評估左心室心肌存活性。

　　　　　Purpose: Low-dose dobutamine echocardiography (LDDE) has been demonstrated as an accurate imaging modality to identify viability after acute myocardial infarction (AMI), but LDDE has its limitations. Myocardial contrast echocardiography (MCE) is a good tool to assess microvascular perfusion. This study was undertaken to compare the effect of real-time MCE and LDDE in early assessment of left ventricular (LV) viability of dyskinesia and akinesia myocardium in patients with AMI.Methods: Forty-five patients had 2-dimensional echocardiography, MCE and LDDE within I week after AMI attack. Two-dimensional echocardiography for evaluation of LV viability was performed within 4 months after discharge.Results: Totally 260 segments of dyskinesis or akinesis were analyzed. MCE visualized perfusion segments, either homogenous or patchy contrast opacification and had a sensitivity of 81.4%, specificity of 76.7%, accuracy of 79.4%, positive predictive value of 82.8% and negative predictive value of 75.0% in predicting LV viability. The accuracy was comparable with LDDE (79.4% vs. 76.8%, p=0.52), although MCE has higher sensitivity (81.4% vs. 68.9%, p＜0.005) and LDDE had higher specificity (76.7% vs. 87.6%, p＜0.001). Average time for MCE study was lower than that of LDDE (374±102 seconds vs. 785±216 seconds, p＜0.001). MCE studies were performed and completed without any complication when compare to 6.7% complication rate in the LDDE studies (p＜0.001).Conclusions: Real-time MCE is more time-saving and safer than LDEE. MCE also has comparable accuracy with LDDE for early assessing of LV viability in patients with AMI, despite the limitation of attenuation artifacts in the infero-posterior segments.