Yamazaki J, Muto H, Kabano T, Yamashina S, Nanjo S, Inoue A
First Department of Internal Medicine, Ohmori Hospital, Toho University School of Medicine, 6-11-1 Ohmori-Nishi, Ohta-ku, Tokyo, 143 Japan.
Am Heart J. 2001 Apr;141(4):645-52. doi: 10.1067/mhj.2001.112783.
Patients with heart failure show signs of cardiac sympathetic dysfunction such as elevation of blood norepinephrine (NE) level, as a result of reduction in the number of sympathetic nerves, decrease in myocardial NE content, accelerated NE turnover or spillover of NE, and NE reuptake disorder at sympathetic nerve endings. In dilated cardiomyopathy (DCM), iodine 123-metaiodobenzylguanidine (MIBG) used clinically as a tracer for imaging of the sympathetic function was found to be useful in evaluation of severity and prognosis.
A total of 143 (123)I-MIBG myocardial single-photon emission computed tomography (SPECT) images were taken at successive intervals on 58 patients with DCM (mean age 54 +/- 11 years), as well as before and after therapy to determine the severity of DCM and the therapeutic effect of beta-blocker. Patients were divided into group A (n = 20), in which left ventricular ejection fraction (LVEF) improved by 10% or more within 6 months after the administration of beta-blocker, and group B (n = 20), in which there was less than a 10% change in LVEF. After (123)I-MIBG myocardial SPECT was taken, the washout rate for the entire left ventricle was calculated from early and delayed images. The estimations of extent score and severity score were based on the polar map prepared from short axial images taken from 17 healthy volunteers (mean age 35 +/- 5 years). There was a significant correlation between LVEF and (123)I-MIBG findings (extent score, severity score, and washout rate) obtained before and after beta-blocker therapy. After beta-blocker therapy, LVEF and (123)I-MIBG findings significantly improved in group A. On the other hand, no change occurred in (123)I-MIBG findings in group B. There was no significant difference in LVEF between group A (32.1% +/- 8.0%) and group B (29.5% +/- 7.2%). Also, there was no significant difference in the washout rate between group A (54.4% +/- 10.9%) and group B (52.9% +/- 7.2%). Comparison of (123)I-MIBG images before beta-blocker therapy of group A and group B revealed that the extent score (26.5 +/- 16.0 vs 44.5 +/- 21.1, respectively; P <.01) and the severity score (24.9 +/- 21.9 vs 58.2 +/- 35.2, respectively; P <.01) on the basis of the early (123)I-MIBG image was significantly lower for group A.
From the above findings, patients with DCM in which (123)I-MIBG uptake is high on early images were expected to show improvement in cardiac function by beta-blocker therapy. Findings also suggested that (123)I-MIBG was useful for examining the severity of DCM, determining the applicability of beta-blocker therapy, estimating the maintenance dosage of beta-blocker, and evaluating prognosis.
心力衰竭患者表现出心脏交感神经功能障碍的迹象，如血去甲肾上腺素（NE）水平升高，这是由于交感神经数量减少、心肌NE含量降低、NE周转加速或溢出以及交感神经末梢NE再摄取障碍所致。在扩张型心肌病（DCM）中，临床上用作交感神经功能成像示踪剂的碘123 - 间碘苄胍（MIBG）被发现对评估严重程度和预后有用。
对58例DCM患者（平均年龄54±11岁）连续间隔进行了143次（123）I - MIBG心肌单光子发射计算机断层扫描（SPECT）成像，并在治疗前后进行，以确定DCM的严重程度和β受体阻滞剂的治疗效果。患者分为A组（n = 20），即给予β受体阻滞剂后6个月内左心室射血分数（LVEF）提高10%或更多的患者，以及B组（n = 20），即LVEF变化小于10%的患者。在进行（123）I - MIBG心肌SPECT成像后，根据早期和延迟图像计算整个左心室的洗脱率。范围评分和严重程度评分的估计基于从17名健康志愿者（平均年龄35±5岁）的短轴图像制备的极坐标图上。β受体阻滞剂治疗前后获得的LVEF与（123）I - MIBG结果（范围评分、严重程度评分和洗脱率）之间存在显著相关性。β受体阻滞剂治疗后，A组的LVEF和（123）I - MIBG结果显著改善。另一方面，B组的（123）I - MIBG结果无变化。A组（32.1%±8.0%）和B组（29.5%±7.2%）之间的LVEF无显著差异。此外，A组（54.4%±10.9%）和B组（52.9%±7.2%）之间的洗脱率也无显著差异。A组和B组β受体阻滞剂治疗前的（123）I - MIBG图像比较显示，基于早期（123）I - MIBG图像的A组范围评分（分别为26.5±16.0和44.5±21.1；P <.01）和严重程度评分（分别为24.9±21.9和58.2±35.2；P <.01）显著较低。
根据上述发现，早期图像上（123）I - MIBG摄取高的DCM患者有望通过β受体阻滞剂治疗改善心功能。研究结果还表明，（123）I - MIBG可用于检查DCM的严重程度、确定β受体阻滞剂治疗的适用性、估计β受体阻滞剂的维持剂量以及评估预后。
