Kitsiou A N, Srinivasan G, Quyyumi A A, Summers R M, Bacharach S L, Dilsizian V
Cardiology Branch, National Heart, Lung, and Blood Institute, and the Department of Nuclear Medicine, National Institutes of Health, Bethesda, MD 20892, USA.
Circulation. 1998 Aug 11;98(6):501-8. doi: 10.1161/01.cir.98.6.501.
In patients with coronary artery disease, stress-redistribution-reinjection thallium scintigraphy provides important information regarding myocardial ischemia and viability. Although both reversible and mild-to-moderate irreversible thallium defects retain metabolically active, viable myocardium, we hypothesized that stress-induced reversible thallium defects may better differentiate reversible from irreversible regional left ventricular dysfunction after revascularization.
Twenty-four patients with chronic coronary artery disease underwent prerevascularization and postrevascularization exercise-redistribution-reinjection thallium single photon emission CT, gated MRI, and radionuclide angiography. After revascularization, mean left ventricular ejection fraction increased from 30+/-9% to 37+/-13% at rest (P<0.001). Before revascularization, abnormal contraction at rest was observed in 56 of 110 reversible and 20 of 37 mild-to-moderate irreversible thallium defects (51% and 54%, respectively). After revascularization, regional contraction improved in 44 of 56 reversible compared with 6 of 20 mild-to-moderate irreversible thallium defects (79% and 30%, respectively; P<0.001). The final thallium content (maximum tracer uptake on redistribution-reinjection images) was significantly higher in regions with reversible defects that improved than in those that did not improve after revascularization (86+/-16% versus 66+/-9%, P<0.001). In contrast, final thallium content was similar in regions with mild-to-moderate irreversible defects that improved and in those that did not improve after revascularization (69+/-9% versus 65+/-10%, P=NS). Furthermore, when asynergic regions were grouped according to the final thallium content, at 60% threshold value, functional recovery was observed in 83% of regions with reversible defects compared with 33% of regions with mild-to-moderate irreversible defects (P<0.001).
These findings suggest that although both reversible and mild-to-moderate irreversible thallium defects after stress retain viable myocardium, the identification of reversible thallium defect on stress in an asynergic region more accurately predicts recovery of function after revascularization. Even at a similar mass of viable myocardial tissue (as reflected by the final thallium content), the presence of inducible ischemia is associated with an increased likelihood of functional recovery.
在冠心病患者中，负荷-再分布-再注射铊闪烁扫描术可提供有关心肌缺血和存活心肌的重要信息。尽管可逆性及轻度至中度不可逆性铊缺损均保留有代谢活性的存活心肌，但我们推测负荷诱发的可逆性铊缺损可能能更好地区分血运重建术后可逆性与不可逆性局部左心室功能障碍。
24例慢性冠心病患者在血运重建术前及术后接受了运动-再分布-再注射铊单光子发射计算机断层扫描、门控磁共振成像及放射性核素血管造影。血运重建术后，静息状态下左心室平均射血分数从30±9%增至37±13%（P<0.001）。血运重建术前，110个可逆性铊缺损中有56个、37个轻度至中度不可逆性铊缺损中有20个在静息时观察到收缩异常（分别为51%和54%）。血运重建术后，56个可逆性铊缺损中有44个区域收缩改善，而20个轻度至中度不可逆性铊缺损中只有6个区域收缩改善（分别为79%和30%；P<0.001）。血运重建后改善的可逆性缺损区域的最终铊含量（再分布-再注射图像上的最大示踪剂摄取量）显著高于未改善区域（86±16%对66±9%，P<0.001）。相比之下，血运重建后改善的轻度至中度不可逆性缺损区域与未改善区域的最终铊含量相似（69±9%对65±10%，P=无显著性差异）。此外，当根据最终铊含量对不协调区域进行分组时，在60%的阈值下，83%的可逆性缺损区域观察到功能恢复，而轻度至中度不可逆性缺损区域只有33%观察到功能恢复（P<0.001）。
这些发现表明，尽管负荷后可逆性及轻度至中度不可逆性铊缺损均保留有存活心肌，但在不协调区域中识别负荷时的可逆性铊缺损能更准确地预测血运重建术后的功能恢复。即使在相似质量的存活心肌组织（由最终铊含量反映）情况下，诱发性缺血的存在与功能恢复可能性增加相关。
