Department of Nuclear Medicine and Molecular Imaging, Amrita Institute of Medical Sciences; Cochin-India.
Anatol J Cardiol. 2020 Aug;24(2):83-91. doi: 10.14744/AnatolJCardiol.2020.99148.
Early identification of viable myocardium in ischemic cardiomyopathy (ICM) patients is essential for early intervention and better clinical outcome. 99mTechnetium (99mTc) sestamibi gated myocardial perfusion imaging (gMPI) is a well-established technique for myocardial viability evaluation. Detection of potentially viable segments is a predictor of hibernating myocardium. ICM patients with hibernation have a better prognosis after revascularization. We used a novel infusion technique to determine better viability detection preoperatively in challenging situations. Like thallium, does prolonged availability of sestamibi in circulation with additional low dose dobutamine steady infusion (DS Inf) facilitate improved myocardial viability?
A total of 58 ICM patients with infarct and left ventricular ejection fraction (LVEF) <45% underwent 99mTc sestamibi bolus injection followed by slow intravenous infusion single-photon emission computed tomography (SPECT) using a 2 day protocol. After acquiring the second set of 99mTc sestamibi infusion images, a third SPECT gMPI was performed during DS Inf.
A 17-segment myocardial model was used; 52 of 58 patients (548/986 segments) demonstrated perfusion defects (nonviable myocardium) on bolus study. Only 24 patients demonstrated viable segments by standard bolus imaging protocol. The slow MIBI infusion study demonstrated 158 viable segments (12 ICM patients), while combined infusion (99mTc sestamibi+DS Inf) exhibited an additional 6 patients with improved myocardial viability. Thus, 18 high risk patients benefited by this novel infusion technique to demonstrate viable myocardium on SPECT. There was a significantly higher sensitivity (p=0.05) and positive predictive value (p=0.01) in viability identification with the combined DS Inf technique. In dysfunctional segments, the rate of concordance for detecting viability between infusion and bolus techniques was 65%. Paired t test showed statistically significant improvement in viability detection with combined infusion compared to the bolus study (p=0.001).
This novel infusion technique was shown to be feasible and incremental in viability detection in ICM patients with severe left ventricular dysfunction. It is a robust tool to guide revascularization, in high risk ICM patients. This study also showed that patients with large transmural MI demonstrated no significant improvement in myocardial perfusion status using either protocol.
早期识别缺血性心肌病（ICM）患者的存活心肌对于早期干预和更好的临床结局至关重要。99mTc 锝（99mTc） sestamibi 门控心肌灌注成像（gMPI）是评估心肌存活能力的成熟技术。检测潜在存活节段是冬眠心肌的预测指标。ICM 患者存在冬眠心肌，经血运重建后预后更好。我们使用一种新的灌注技术，在具有挑战性的情况下，术前确定更好的存活能力检测。像铊一样，循环中 sestamibi 的延长可用性和额外的低剂量多巴酚丁胺稳定输注（DS Inf）是否有助于改善心肌存活能力？
58 例梗死伴左心室射血分数（LVEF）<45%的 ICM 患者接受 99mTc sestamibi 弹丸注射，随后采用 2 天方案进行缓慢静脉输注单光子发射计算机断层扫描（SPECT）。在获得第二组 99mTc sestamibi 输注图像后，在 DS Inf 期间进行第三次 SPECT gMPI。
使用 17 节段心肌模型；58 例患者中的 52 例（548/986 节段）在弹丸研究中显示灌注缺陷（无活力心肌）。仅 24 例患者通过标准弹丸成像方案显示存活节段。缓慢的 MIBI 输注研究显示 158 个存活节段（12 例 ICM 患者），而联合输注（99mTc sestamibi+DS Inf）显示另外 6 例患者的心肌存活能力得到改善。因此，18 例高危患者受益于这种新的灌注技术，在 SPECT 上显示存活心肌。联合 DS Inf 技术在检测存活能力方面的灵敏度（p=0.05）和阳性预测值（p=0.01）显著提高。在功能障碍节段，输注技术和弹丸技术检测存活能力的一致性率为 65%。配对 t 检验显示，与弹丸研究相比，联合输注在检测存活能力方面具有统计学意义上的显著改善（p=0.001）。
这项新的灌注技术在严重左心室功能障碍的 ICM 患者中显示出可行性和检测存活能力的增量。它是一种强大的工具，可指导高危 ICM 患者的血运重建。该研究还表明，接受大透壁性 MI 的患者使用任何一种方案均未显著改善心肌灌注状态。
