Iodine-123-Metaiodobenzylguanidine Myocardial Scintigraphy in Patients with Dilated Cardiomyopathy : Correlation between Myocardial MIBG Uptake and Echocardiographic Parameters

Ha, Jong Won; Lee, Jong Doo; Chung, Namsik; Jang, Yangsoo; Kim, Byung Soo; Kwan, June; Lee, Moon Hyoung; Cha, Dong Hun; Lee, Young Joon; Shim, Won Heum; Cho, Seung Yun; Kim, Sung Soon

Abstract

BACKGROUND
The prognosis of patients with dilated cardiomyopathy remains poor. Doppler echocardiography and cardiac iodine-123-metaiodobenzylguanidine(MIBG) myocardial scintigraphy are useful non-invasive diagnostic modalities to assess the prognosis in these patients. However, the relationship between myocardial MIBG uptake and Doppler echocardiographic. variables was not well investigated. We analyzed the cardiac MIBG imaging in 40 patients with dilated cardiomyopathy and assessed the correlation between the echocardiographic parameters and myocardial MIBG uptake. MIBG uptake(DHM), assessed as the heart/mediastinum ratio measured on anterior view image obtained 4 hours after injection, was compared with M-mode(left ventricular end-diastolic dimension, left ventricular ejection fraction) and Doppler parameters.
RESULTS
1) Early and delayed MIBG uptake of heart were significantly lower in patient group compared with normal control subjects. There were no significant differences in lung and mediastinum uptake of MIBG between the two groups. 2) Early and delayed MIBG uptake ratios of the heart to lung and heart to mediastinum were significantly lower in patient group compared with those of normal control subjects. 3) DHM was significantly lower in patients with NYHA functional class 3, 4 than those with NYHA functional class 1, 2 in patient group. There was, however, no significant difference of DHM in patient group divided by the degree of mitral regurgitation and left ventricular diastolic filling pattern. 4) There were no significant correlations between DHM and other prognostic factors(left ventricular end-diastolic dimension, left ventricular ejection fraction, peak velocity of early diastolic filling(E velocity), deceleration time of E wave, cardiac output, pulmonary capillary wedge pressure, left ventricular end-diastolic pressure and 24hr urine norepinephrine).
CONCLUSION
Iodine-123-MIBG scan is a useful noninvasive imaging modality in the assessment of cardiac sympathetic neuronal integrity in patients with dilated cardiomyopathy. There were no significant correlations between cardiac MIBG uptake and other prognostic factors. The cardiac MIBG uptake probably can be utilized as an independent prognostic factor, hence it would be suggested that a large prospective clinical study is needed to consolidate these findings.