Clinical value of lung uptake of iodine-123 metaiodobenzylguanidine (MIBG), a myocardial sympathetic nerve imaging agent, in patients with chronic heart failure

Predictors of outcome in patients with de novo diagnosis of heart failure with reduced ejection fraction: Role of combined myocardial and lung Iodine-123 Meta-Iodobenzylguanidine imaging

BACKGROUND

The predictors of outcome in patients with de novo diagnosis of heart failure (HF) with reduced ejection fraction (HFrEF) are poorly known.

METHODS AND RESULTS

All consecutive HFrEF patients admitted between October 2012 and November 2017 with their first episode of HF were scheduled for an outpatient follow-up. After 3 months, patients with confirmed HFrEF underwent Iodine-123 Meta-Iodobenzylguanidine imaging. We defined three study endpoints: HF rehospitalization, cardiac death and all-cause death. Eighty-four patients were enrolled. During follow-up (39.9 ± 18.6 months) HF rehospitalization occurred in 33 cases, cardiac death in 18 and all-cause death in 24. At multivariate analysis, systolic pulmonary arterial pressure (sPAP; HR: 1.047; p = .027) and Late lung to heart ratio (L/H; HR: 1.341; p < .001) independently predict HF rehospitalization; left ventricular end-systolic volume (LVESV; HR: 1.016; p = .017), sPAP (HR: 1.064; p = .034) and Late L/H (HR: 1.323; p = .009) were predictors of cardiac death; LVESV (HR: 1.013; p = .018) and Late L/H (HR: 1.245; p = .012) were independent predictors of all-cause death. Kaplan-Meier analysis of the individual predictors confirmed their prognostic ability during follow-up; of note, the Late L/H cut-off of 1.1 improved the risk stratification capability of echocardiographic parameters.

CONCLUSIONS

Late L/H independently predicts HF rehospitalization, cardiac death and all-cause death in patients with de novo diagnosis of HFrEF and improves the prognostic stratification capability of conventional echocardiographic parameters.

Risk stratification assessed by combined lung and heart iodine-123 metaiodobenzylguanidine uptake in patients with idiopathic dilated cardiomyopathy

Iodine-123 metaiodobenzylguanidine (123I-MIBG) has been used to assess myocardial sympathetic nervous activity and severity of heart failure. (123)I-MIBG is also used as a potential marker of pulmonary endothelial cell function and may be related to pulmonary hypertension. Thus, we hypothesized that combined assessment of lung and heart 123I-MIBG kinetics predicts future clinical outcome more accurately than myocardial evaluation alone in patients with chronic heart failure. To test this hypothesis, we examined 123I-MIBG scintigrams in 62 consecutive patients with idiopathic dilated cardiomyopathy. Anterior planar images were obtained 15 minutes and 3 hours after 123I-MIBG injection. Cardiac and pulmonary 123I-MIBG activities were quantified as heart-to-mediastinum activity ratio and lung-to-mediastinum activity ratio. We introduced lung-to-heart activity ratio as the new 123I-MIBG parameter including myocardial sympathetic nerve activity and pulmonary endothelial cell function. Delayed lung-to-heart ratio was correlated with pulmonary vascular resistance (r = 0.48, p <0.0001), disease duration (r = 0.49, p <0.0001), and number of heart failure episodes (r = 0.55, p <0.0001). During a mean follow-up of 25 months, 15 patients had a cardiac event. Area under receiver operating characteristic curves for prediction of the event was greatest in delayed lung-to-heart ratio (lung to heart 0.92, heart to mediastinum 0.83, lung to mediastinum 0.80). In multivariate analysis, the lung-to-heart ratio (hazard ratio 2.76/0.1 increase, p = 0.002) was selected as an independent predictor for a future cardiac event. In conclusion, the combined assessment of lung and heart 123I-MIBG uptake may help to predict future clinical outcome for patients with idiopathic dilated cardiomyopathy more accurately than myocardial evaluation alone.

Lung-uptake and -washout of MIBG in sarcoidosis

BACKGROUND

The aim of this study was to evaluate the uptake and -washout of I-123 meta-iodobenzylguanidine (MIBG), reflecting norepinephrine metabolism, in the lungs in patients with sarcoidosis.

METHODS

Lung I-123 MIBG kinetics was assessed in 43 patients with sarcoidosis. The range of disease duration was 1-16 years (median: 3 years). Thirteen patients had radiographic stage 0-I, 30 patients had radiographic stage II-IV. Serological clinical parameters and small fibre neuropathy, as assessed by temperature threshold testing (TTT) were measured in 39/43 patients. 31/39 patients had an abnormal TTT. Eleven healthy controls participated in this study. Both dual head planar and dual headed SPECT images of the thoracic regions were made. The uptake of I-123 MIBG and the washout percentage were calculated in sarcoidosis patients and compared with the healthy persons.

RESULTS

Lung I-123 MIBG uptake in patients with sarcoidosis did not differ from controls. The lung washout of I-123 MIBG was significantly (p<or=0.01) decreased in sarcoidosis. Remarkably this was most clearly seen in patients with an abnormal TTT and in patients with more advanced radiographic pulmonary involvement (radiographic stages II-IV) but not in patients with decreased lung function (FVC<80% or DLCO<80%).

CONCLUSION

The inflammatory process of the lungs in sarcoidosis seems not to affect pulmonary vasculature. In sarcoidosis decreased lung washout of I-123 MIBG might, at least partly, be explained by sympathetic autonomic nerve dysfunction. Future studies are needed to explore the clinical relevance of this observation.

Involvement of pulmonary endothelial cell injury in the pathogenesis of pulmonary fibrosis: clinical assessment by 123I-MIBG lung scintigraphy

PURPOSE

Pulmonary microvascular endothelial injury may be involved in the pathogenesis of pulmonary fibrosis (PF). The aim of this study was to evaluate the pulmonary vascular status in patients with PF by lung scintigraphic assessment of 123I-metaiodobenzylguanidine (123I-MIBG), which reflects latent endothelial cell lesions.

METHODS

We assessed lung 123I-MIBG kinetics and clinical indices in 23 PF patients and 16 controls. Mean uptake ratios of lung to mediastinum (L/M) were calculated in anterior planar images at 30 (early image) and 270 (delayed image) min after intravenous injection of 123I-MIBG. The pulmonary mean washout rate (WR) of 123I-MIBG was also calculated.

RESULTS

The L/M ratio in early images, but not in delayed images, was significantly lower in the PF patients than in the controls (L/M(early) 1.41+/-0.14 vs 1.53+/-0.10, p<0.01; L/M(delayed) 1.28+/-0.10 vs 1.33+/-0.07, p=NS). WR was significantly reduced in the PF patients compared with the controls (28.6%+/-3.1% vs 34.2%+/-5.1%, p<0.001). In the study subjects (PF patients plus controls) there were significant relationships between lung WR of (123)I-MIBG and other diagnostic parameters for the severity of PF, such as vital capacity (r=0.625, p<0.0001), total lung capacity (r=0.691, p<0.0001), carbon monoxide diffusing capacity (r=0.622, p<0.0001), serum angiotensin-converting enzyme activity (r=0.422, p<0.01), carbohydrate antigen KL-6 levels (r=-0.495, p<0.01) and surfactant protein-D levels (r=-0.461, p<0.01). When control subjects were excluded, similar significant correlations were observed between WR and %TLC (r=0.508, p<0.05), DL(CO) (r=0.593, p<0.01) and serum ACE activity (r=0.515, p<0.05) in the PF patients.

CONCLUSION

These results suggest that endothelial cell injury plays a significant role in the pathogenesis of PF, and that lung WR of 123I-MIBG, which is a specific marker of endothelial damage, can serve as a novel diagnostic tool to evaluate the functional severity of PF.