Evaluation of beta-blocker therapy in patients with dilated cardiomyopathy--Clinical meaning of iodine 123-metaiodobenzylguanidine myocardial single-photon emission computed tomography.

BACKGROUND: 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. METHODS AND RESULTS: 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. CONCLUSIONS: 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.

A case of favorable dilation of protected left main coronary artery lesion achieved through performance of adjunctive DCA on residual stenosis following use of rotablator.

It is believed that directional coronary atherectomy (DCA) is more suitable than percutaneous transluminal coronary angioplasty for lesions such as severe eccentric lesions, ostial lesions, and branch lesions. However, it remains a fact that lesions that are also highly calcified are often suboptimal, since there may be difficulties such as in insertion of the housing and in sufficient cutting and removal. On the other hand, Rotablator is effective on calcified lesions, but afterward, dilation by balloon angioplasty for residual stenosis becomes necessary in many cases. This is a report of the authors' experience on an interesting case in which favorable dilation of a lesion in the protected left main coronary artery (LMCA) was achieved by using Rotablator after confirmation of a high degree of calcification by means of intravascular ultrasound (IVUS) echocardiograhy, followed by the performance of DCA on the residual stenosis.

[Clinical meaning of 123I-MIBG myocardial SPeCT in patients with dilated cardiomyopathy].

MIBG-myocardial SPECT was performed on patients with dilated cardiomyopathy (DCM) undergoing treatment with beta blocker (Nipradilol). The findings of MIBG-myocardial SPECT were compared with the changes in cardiac function obtained by echocardiograms. The patients enrolled in the study were seven males who has been diagnosed as definitely suffering from DCM according to diagnostic guidelines provided by the Ministry of Health and Welfare. The patients were aged 57.5 +/- 10.2 years. Following intravenous administration of 111 MBq (3 mCi) of MIBG, myocardial SPECT was taken 20 minutes, and 4 hours later. The washout rate of the left ventricular wall was higher in the unchanged group (40.7 +/- 1.2%) than in the improved group (30.3 +/- 6.1%). Both the early and delayed images showed higher extent and severity scores for the unchanged group than for the improved group. A correlation of LVEF with the washout rates was demonstrated (r = -0.819, p < 0.05). A correlation was also observed between the variations in LVEF before and after beta blocker therapy with the washout rates (r = -0.969, p < 0.01), MIBG-myocardial SPECT suggested possibility of the evaluation of severity and prognosis in the patients with DCM.

[The usefulness of three dimensional imaging of the myocardium using three heads SPECT camera (PRISM-3000)].

The SPECT unit using a 3 heads camera (PRISM-3000) has an advantage over the conventional one head camera SPECT unit because it can complete full circle scans (360 degrees scans) within a short time, and because the non-circular orbit of the camera heads fitting the individual form of the body has improved the spatial resolution. In addition, the high speed data processing has reduced the time for scan, enabling the three dimensional imaging system clinically applicable. In the present study, this modern technique was used to examined the myocardium in patients with ischemic heart disease so as to evaluate it for usefulness and depict problem to be solved. In patients with myocardial infarction, images obtained with a PRISM-3000 machine could provide more objective information on infarcts than conventional images. In patients with angina pectoris, delayed images obtained 3 hours after exercise by the new method were superior to conventional ones in power of demonstrating redistribution. The setting of the threshold for ischemic lesions at 40-50% hampers the assessment of the severity of ischemia. A new program should be introduced to solve this problem.