Sciagrà R, Bolognese L, Rovai D, Sestini S, Santoro G M, Cerisano G, Marini C, Buonamici P, Antoniucci D, Fazzini P F
Department of Clinical Physiopathology, University of Florence, Italy.
J Nucl Med. 1999 Mar;40(3):363-70.
The extent of myocardial salvage after primary percutaneous transluminal coronary angioplasty (PTCA) in acute myocardial infarction (AMI) is variable and cannot be predicted on the basis of either vessel patency or early regional wall motion assessment. The aim of this study was to evaluate the reliability of microvascular integrity, as shown by myocardial contrast echocardiography (MCE), as an indicator of tissue salvage and a predictor of late functional recovery, and to compare MCE with the quantification of tracer activity in sestamibi perfusion imaging.
Twenty-six patients with AMI who received successful treatment with primary PTCA were examined with MCE during cardiac catheterization immediately before and after vessel recanalization. Myocardial contrast effect was scored as 0 (absent), 0.5 (partial) or 1 (normal). Wall motion was assessed by two-dimensional echocardiography on admission and 1 mo later with a 16-segment model and 4-point score. Resting sestamibi SPECT was collected within 1 wk after AMI. The risk area was defined by MCE as the sum of the segments with no perfusion (score 0) before PTCA. Myocardial viability was defined by MCE as an increase in contrast score in the same segments after PTCA and by sestamibi SPECT as a preserved tracer activity (>60% of peak activity). The functional recovery after 1 mo detected by two-dimensional echocardiography was the reference standard for viability.
A total of 50 segments showed perfusion defects before PTCA (risk area). Immediately after PTCA, the MCE score increased in 44 of 50 segments, whereas sestamibi SPECT showed preserved activity in 22 of 50 segments. After 1 mo, the wall motion score decreased in 22 of 50 segments (viable segments) and was unchanged in the remaining 28 segments. Thus, MCE showed a sensitivity of 91% and a specificity of 14% in detecting viable myocardium, whereas sestamibi SPECT showed a lower sensitivity (68%) but a significantly higher specificity (75%; P < 0.00001). The positive predictive values were 45% and 68% for MCE and SPECT (P < 0.005), respectively, and the negative predictive values were 67% and 71%, respectively. On a patient basis, SPECT was more specific (79% versus 21%; P < 0.01) and showed a higher overall predictive accuracy (88% versus 50%; P < 0.01) than MCE.
The demonstration of microvascular integrity by MCE performed immediately after primary PTCA has a limited diagnostic value in predicting salvaged myocardium. Conversely, tracer activity quantification in resting sestamibi SPECT performed in a later stage is confirmed to be a reliable approach for recognizing myocardial stunning and predicting functional recovery.
急性心肌梗死（AMI）患者接受直接经皮冠状动脉腔内血管成形术（PTCA）后心肌挽救的程度存在差异，无法根据血管通畅情况或早期局部室壁运动评估来预测。本研究的目的是评估心肌对比超声心动图（MCE）所示微血管完整性作为组织挽救指标和晚期功能恢复预测指标的可靠性，并将MCE与锝-99m甲氧基异丁基异腈（sestamibi）灌注显像中示踪剂活性定量进行比较。
26例接受直接PTCA成功治疗的AMI患者在心脏导管插入术期间、血管再通前后立即接受MCE检查。心肌对比效果评分为0（无）、0.5（部分）或1（正常）。入院时及1个月后采用二维超声心动图和16节段模型及4分制评估室壁运动。AMI后1周内进行静息sestamibi单光子发射计算机断层显像（SPECT）。MCE将PTCA前无灌注（评分0）的节段总和定义为危险区域。MCE将PTCA后相同节段对比评分增加定义为心肌存活，sestamibi SPECT将示踪剂活性保留（>峰值活性的60%）定义为心肌存活。二维超声心动图检测的1个月后功能恢复情况为存活的参考标准。
共50个节段在PTCA前显示灌注缺损（危险区域）。PTCA后立即，50个节段中的44个节段MCE评分增加，而50个节段中的22个节段sestamibi SPECT显示活性保留。1个月后，50个节段中的22个节段（存活节段）室壁运动评分降低，其余28个节段无变化。因此，MCE检测存活心肌的敏感性为91%，特异性为14%，而sestamibi SPECT敏感性较低（68%），但特异性显著较高（75%；P<0.00001）。MCE和SPECT的阳性预测值分别为45%和68%（P<0.005），阴性预测值分别为67%和71%。在患者层面，SPECT比MCE更具特异性（79%对21%；P<0.01），总体预测准确性更高（88%对50%；P<0.01）。
直接PTCA后立即进行的MCE显示微血管完整性对预测挽救心肌的诊断价值有限。相反，后期进行的静息sestamibi SPECT示踪剂活性定量被证实是识别心肌顿抑和预测功能恢复的可靠方法。
