Significance of performing 123I-metaiodobenzylguanidine myocardial scintigraphy at different times for the long-term prediction of cardiac events in patients with dilated cardiomyopathy.

OBJECTIVES: Although it has been reported that (123)I-metaiodobenzylguanidine (MIBG) myocardial scintigraphy is useful for assessing the prognosis of dilated cardiomyopathy (DCM), there have been no reports regarding how interval MIBG imaging should be performed during follow-up. We investigated the significance of performing MIBG at different times for the long-term prediction of cardiac events in DCM patients. METHODS: The participants were 36 DCM patients who did not sustain cardiac events for 2 years after beta-blocker induction. MIBG was performed 6 months and 2 years after beta-blocker induction and the images analyzed to obtain the extent score, severity score (SEV), and the washout rate. Echocardiography was performed at the same time. RESULTS: Eight patients experienced a cardiac event during follow-up (cardiac death: two patients; heart failure requiring hospitalization: six patients). Although no significant difference was found in any MIBG parameters or left ventricular ejection fraction between patients who experienced a cardiac event and those who did not after 6 months, early extent score, early SEV, delayed SEV, and washout rate were found to be significantly higher for patients who experienced a cardiac event after 2 years. In multivariate analysis using Cox proportional hazard model, none of the MIBG parameters or left ventricular ejection fraction after 6 months was identified as a predictor of cardiac events. However, delayed SEV after 2 years (hazard ratio 1.067, P = 0.0435) was a significant predictor of cardiac events. CONCLUSION: The study suggested that performing MIBG at least once every 2 years allows long-term prediction of cardiac events in the follow-up of DCM patients.

Evaluation of sympathetic activity by 123I-metaiodobenzylguanidine myocardial scintigraphy in dilated cardiomyopathy patients with sleep breathing disorder.

BACKGROUND: Because increased sympathetic nervous activity (SNA) in patients with dilated cardiomyopathy (DCM) associated with sleep breathing disorder (SBD) is known to deteriorate the prognosis of cardiac failure, (123)I-metaiodobenzylguanidine (MIBG) myocardial scintigraphy was used as the investigative tool in the present study. METHODS AND RESULTS: The study group comprised 53 patients (47 men, 6 women; mean age 56+/-3 years) with chronic stable DCM. Patients were divided into SBD(+) or SBD(-) group according to 24-h pulse oximetry results. SBD(+) was defined when the 3% oxygen desaturation index was more than 15/h during sleep. In total, 32 patients were SBD(-) and 21 were SBD(+). In both groups, pulse oximetry were performed during sleep and awakening pulse rate, and measurement of the blood levels of catecholamines and B-type natriuretic peptide was performed. MIBG myocardial scintigraphy and echocardiography were performed at the same time. No significant difference was found between the 2 groups in catecholamine levels or left ventricular ejection fraction. However, MIBG had a significantly increased washout rate and a significantly decreased delayed heart to mediastinum ratio in the SBD(+) group compared with the SBD(-) group. CONCLUSIONS: SNA is increased in DCM patients when associated with SBD. MIBG myocardial scintigraphy may be a sensitive method of detecting increased SNA.

Prediction of cardiac events in patients with dilated cardiomyopathy using 123I-BMIPP and 201Tl myocardial scintigraphy.

OBJECTIVE: Various clinical trials for dilated cardiomyopathy (DCM) have demonstrated that the prognosis as well as cardiac function is improved by the administration of beta-blocker therapy. On the other hand, 123I-betamethyl-p-iodophenyl-pentadecanoic acid (BMIPP) reflects myocardial fatty acid metabolism and is considered to be a more sensitive tracer than perfusion tracers. In this study, the efficacy of DCM for the evaluation of myocardial damage and the prediction of cardiac events was studied using 123I-BMIPP and 201TI (Tl) myocardial scintigraphy. METHODS: Study subjects comprised 33 DCM patients, divided into a cardiac event group (event, n = 9) and an event-free group (event free, n = 24). An extent score (ES) and severity score (SS) were calculated for each BMIPP image. BMIPP and Tl images were divided into 17 segments, and total defect scores (TDS) were calculated for each. The TDS of the BMIPP and Tl images were compared with score differences greater than or equal to 4 and less than 4 defined as mismatch and non-mismatch, respectively. RESULTS: The TDS of BMIPP was significantly higher in the event group than in the event-free group (P < 0.05). The ES and SS were significantly higher in the event group than in the event-free group (P < 0.01). The comparison in the 2 x 2 contingency tables showed that the occurrence of non-mismatch was significantly higher in the event-free group (chi2 test; P < 0.01). The ES of BMIPP was a significant predictor of cardiac events in the multivariate analysis (P < 0.01). CONCLUSIONS: These results suggest that the ES for BMIPP is useful as a predictor of cardiac events in DCM.

[Recurrent ampulla cardiomyopathy showing prolonged sympathetic nerve function disorder: a case report].

A 58-year-old woman with chronic renal failure had been undergoing maintenance hemodialysis. Ampulla cardiomyopathy recurred in association with prolonged sympathetic nerve function disorder. Periodical evaluation of the patient's condition using 123I-metaiodobenzylguanidine (MIBG) myocardial scintigraphy was continued since the first attack at age 55 years. The initial washout rate was high at 58.3%, and was still high at 33.0% when she was discharged following improvement in wall motion, and remained high at 45.4% 1 year after discharge. Recurrence occurred at age 58 years, when a high washout rate of 48.6% was observed. High washout rate values of 49.5% and 40.1% were also observed 2 and 9 months after discharge, respectively, following improvement in wall motion abnormalities. 123I-MIBG can be used to assess the course of recurrent ampulla cardiomyopathy, and can objectively evaluate sympathetic nerve function disorders. This interesting case suggests that sympathetic nerve function disorder is closely related to the pathophysiology of this disorder.

Usefulness of meta-[123I]iodobenzylguanidine myocardial scintigraphy for predicting cardiac events in patients with dilated cardiomyopathy who receive long-term beta blocker treatment.

OBJECTIVE: Large-scale clinical trials have demonstrated that beta blocker therapy improves the prognosis of dilated cardiomyopathy (DCM), but cardiac events sometimes occur even in patients showing favourable response to the therapy. In this study, the usefulness of meta-iodobenzyguanidine (MIBG) in predicting cardiac events was investigated in DCM patients successfully receiving long-term treatment with beta blockers. METHODS: The subjects were 53 patients with DCM (including 10 women; mean age, 56.5+/-10.9 years) who could continue beta blocker therapy for more than 6 months. MIBG was performed within 1 year of commencing the therapy. The extent score, severity score and washout rate were obtained from single photon emission computed tomography images. At the same time, left ventricular ejection fraction (LVEF) and left ventricular end diastolic diameters were measured by echocardiography. The endpoints were cardiac events (cardiac death and admission to hospital due to heart failure or arrhythmia), and patients were observed for an average of 1314+/-986 days (150-4100 days). RESULTS: Cardiac events occurred in nine patients during the observation period. The multivariate statistical analysis demonstrated that the delayed extent score was the strongest significant predictive factor, (hazard ratio 1.036, P<0.01). while LVEF was not a predictive factor. Both the improvement of LVEF and MIBG were significant predictive factors. The improvement of washout rate was the strongest. CONCLUSION: Parameters of MIBG but not of LVEF were useful in predicting cardiac events in DCM patients whose condition had been successfully stabilized by the introduction of beta blockers.

Usefulness of 123I-metaiodobenzylguanidine myocardial scintigraphy in the prediction of cardiac events in patients with cardiomyopathy showing stabilization of symptoms or preserved cardiac function.

OBJECTIVE: It is not rare for patients with cardiomyopathy to be asymptomatic for long periods or to show improved cardiac function following various medical interventions. Conversely, cardiac events sometimes occur in those patients, requiring close observation. We assessed the usefulness of 123I-metaiodobenzylguanidine myocardial scintigraphy (MIBG) to predict the occurrence of cardiac events in patients with stable cardiomyopathy. METHODS: The subjects comprised 74 outpatients with stable cardiomyopathy. MIBG was performed calculate the extent score, severity score, washout rate (WR), and heart-to-mediastinum ratio. At about the same time, the left ventricular ejection fraction (LVEF) by echocardiography and the plasma brain natriuretic peptide were measured. The mean observation period extended for 741+/-437 days with an end point of cardiac events (cardiac death, heart failure requiring hospitalization, and arrhythmias requiring hospitalization). RESULTS: During the mean follow-up period, 15 cardiac events occurred. Results of multivariate analysis revealed that LVEF was the most powerful predictor of cardiac events (0.006, p < 0.01). However, WR was the only significant predictor of hard events such as cardiac death (1.171, p < 0.001) and cardiac events in the group of patients who preserved cardiac function with LVEF 0.4 or higher (1.079, p < 0.05). CONCLUSION: Combined use of LVEF and WR is useful to predict the occurrence of cardiac events in patients with stable cardiomyopathy.

Usefulness of 123I-metaiodobenzylguanidine myocardial scintigraphy for predicting the effectiveness of beta-blockers in patients with dilated cardiomyopathy from the standpoint of long-term prognosis.

PURPOSE: The usefulness of 123I-metaiodobenzylguanidine (MIBG) myocardial scintigraphy in predicting the effectiveness of beta-blocker therapy in dilated cardiomyopathy (DCM) was investigated from the standpoint of long-term prognosis. METHODS: The subjects were 53 DCM patients in whom beta-blockers had been successfully introduced and used for 6 months or longer. When symptoms were stable before the introduction of beta-blockers and for up to 1 year thereafter, MIBG myocardial single-photon emission computed tomography was performed and the images analysed to obtain the extent score (EXT), severity score (SEV) and washout rate (WR). At the same time, echocardiography was performed to measure left ventricular ejection fraction (LVEF). Thereafter, patients were placed under observation for an average of 1,314+/-986 days, with the occurrence of cardiac events as the endpoint. RESULTS: The degree of improvement in WR after introduction of beta-blockers was a significant predictor of cardiac events. In fact, none of the patients whose improvement in WR was valued at 10 or higher had cardiac events. Accordingly, using improvement in WR of 10 as the cut-off value, the patients were divided into two groups, "improved" and "unimproved". There were significant differences between the groups in respect of early EXT, early SEV and WR before the introduction of beta-blockers. As regards predictors of WR improvement, multivariate logistic regression analysis demonstrated that early EXT, WR and LVEF were significant predictors. CONCLUSION: This study shows that, from the standpoint of long-term prognosis, DCM patients who would benefit the most from beta-blocker therapy are those with low early EXT and early SEV and high WR before beta-blocker introduction regardless of LVEF values.

The effect of beta-blocker on hamster model BIO 53.58 with dilated cardiomyopathy determined using 123I-MIBG myocardial scintigraphy.

OBJECTIVE: 123I-metaiodobenzylguanidine (MIBG) myocardial scintigraphy is currently used to evaluate cardiac sympathetic nerve function, but MIBG also has the capacity to evaluate dilated cardiomyopathy (DCM) severity and therapeutic effectiveness. In this study, we administered beta-blockers to a DCM hamster model and evaluated the effect of therapy using MIBG. We also pathologically compared the effects of myocardial fibrosis suppression. METHODS: BIO 53.58 hamsters were divided into the following five groups based on beta-blocker administration: vehicle (COT), 2 mg/kg/day carvedilol (CLT), 20 mg/kg/day (CHT) carvedilol, 4 mg/kg/day (MLT) metoprolol, 40 mg/kg/day (MHT) metoprolol. F1B hamsters were administered a vehicle (COF). Plasma catecholamine, noradrenaline (p-NADR), adrenaline (p-ADR), and dopamine (p-DOPA) were assayed, and MIBG was performed. The count ratio of the heart to the mediastinum (H/M) and left ventricle myocardial washout ratio (WR) were calculated. We then performed an autopsy and calculated the percent change in fibrotic area from myocardial sections. RESULTS: H/M of the initial image in the COT group was significantly lower at 2.4 +/- 0.2 than the 2.9 +/- 0.7 in the COF group (p < 0.05). The CLT and CHT groups had higher H/M values compared to the COT group (3.1 +/- 0.6, 3.0 +/- 0.6 versus 2.4 +/- 0.2: p < 0.05). Significant correlations were evident between the H/M of the delayed image and p-NADR and p-DOPA (p < 0.05, p < 0.01, respectively) as well as between WR and p-NADR and p-DOPA (p < 0.05). Percent change in fibrotic area was significantly lower in the beta-blocker groups than in the COT group (p < 0.05). Significant negative correlations were seen between the H/M of the delayed image and the percent change in fibrosis area. CONCLUSIONS: The delayed image H/M and WR acutely reflected cardiac disorder and sympathetic nerve function disorder in BIO 53.58 hamsters. In the carvedilol-administered groups, there was improvement compared to the initial H/M image, indicating the efficacy of the beta-blocker in DCM.