962-64 Determination of Extent of Viable Myocardium within Infarct-Related Arterial Perfusion Beds Using Intracoronary Tc-99m-Sestamibi Injection

Precise determination of the extent of residual viable myocardium within the infarct-related vascular territory in patients with myocardial infarction may be important in assessing potential benefit from revascularization, yet measurement of this parameter has proven difficult. To address this issue, 15 patients with predominantly single-vessel coronary disease and prior myocardial infarction (mean 1 month previously) were studied. Subselective intracoronary Tc-99m-sestamibi injections were performed at the site of epicardial stenosis in the infarct-related artery to measure the extent of myocardium at risk (risk area, RA). A separate injection of sestamibi was performed intravenously at rest to measure infarct size (IS). RA and IS were determined quantitatively by circumferential profile analysis using a threshold value of 60% of peak counts, The ratio of IS/RA was used to reflect the proportion of the area at risk which was non-viable. IS, RA and IS/RA were then compared with clinical and angiographic variables.As expected, a strong correlation was found between IS and RA (r=0.82, p<0.0005); the IS/RA ratio showed an inverse relationship with ejection fraction by ventriculography (p<0.02). An IS/RA ratio<0.6 was predictive of better global and regional ventricular function and preserved (TIMI grade 3) antegrade or collateral flow (all p<0.05). No independent relation was seen between IS/RA or IS and antegrade or collateral flow alone.Thus: 1) RA size is an important determinant of IS; 2) an IS/RA ratio<0.6 reflects the presence of residual viable myocardium within the infarctrelated arterial bed. The IS/RA ratio is inversely correlated with clinical and angiographic indicators of viability. This parameter may provide an independent means of assessing viability within a given coronary vascular territory.

在心肌梗死患者中精确测定梗死相关血管区域内残余存活心肌的范围，对于评估血运重建的潜在益处可能很重要，但该参数的测量已被证明是困难的。为了解决这一问题，对15例主要为单支冠状动脉疾病且既往有心肌梗死（平均在1个月前）的患者进行了研究。在梗死相关动脉的心外膜狭窄部位进行选择性冠状动脉内锝 - 99m - sestamibi注射，以测量危险心肌的范围（危险区域，RA）。在静息状态下静脉单独注射sestamibi以测量梗死面积（IS）。通过圆周剖面分析，使用峰值计数60%的阈值定量测定RA和IS。IS/RA比值用于反映危险区域中非存活部分的比例。然后将IS、RA和IS/RA与临床和血管造影变量进行比较。正如预期的那样，发现IS和RA之间有很强的相关性（r = 0.82，p < 0.0005）；IS/RA比值与心室造影所测射血分数呈负相关（p < 0.02）。IS/RA比值<0.6可预测更好的整体和局部心室功能以及保留（TIMI 3级）的前向血流或侧支血流（所有p < 0.05）。在IS/RA或IS与单独的前向血流或侧支血流之间未发现独立关系。因此：1）RA大小是IS的一个重要决定因素；2）IS/RA比值<0.6反映了梗死相关动脉床内存在残余存活心肌。IS/RA比值与存活的临床和血管造影指标呈负相关。该参数可能为评估特定冠状动脉血管区域内的存活情况提供一种独立的方法。