Aritomo Inoue

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

PurposeThe usefulness of 123I-metaiodobenzylguanidine (MIBG) myocardial scintigraphy in predicting the effectiveness of β-blocker therapy in dilated cardiomyopathy (DCM) was investigated from the standpoint of long-term prognosis.MethodsThe subjects were 53 DCM patients in whom β-blockers had been successfully introduced and used for 6 months or longer. When symptoms were stable before the introduction of β-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.ResultsThe degree of improvement in WR after introduction of β-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 β-blockers . As regards predictors of WR improvement, multivariate logistic regression analysis demonstrated that early EXT, WR and LVEF were significant predictors.ConclusionThis study shows that, from the standpoint of long-term prognosis, DCM patients who would benefit the most from β-blocker therapy are those with low early EXT and early SEV and high WR before β-blocker introduction regardless of LVEF values.

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

ObjectiveLarge-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. MethodsThe 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). ResultsCardiac 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. ConclusionParameters 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 of123I-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 of123I-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.

The effect of β-blocker on hamster model BIO 53.58 with dilated cardiomyopathy determined using123I-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 administeredβ- 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 β-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. FIB 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 β-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 β-blocker in DCM.