Relationship between impaired cardiac sympathetic activity and spatial dyssynchrony in patients with non-ischemic heart failure: assessment by MIBG scintigraphy and tagged MRI

[123 I-MIBG scintigraphy in the assessment of heart failure prognosis and effectiveness of cardiac resynchronization therapy]

Cardiac resynchronization therapy (CRT) is one of the methods of treating patients with chronic heart failure, which can reduce the mortality rate of this group. Scintigraphic assessment of sympathetic myocardial innervation allows us to evaluate the heart failure prognosis and the effectiveness of interventional treatment. The method is based on use of the radiopharmaceutical 123 I-methiodiobenzylguanidine (123 I-MIBG), which is a structural analogue of norepinephrine and is able to selectively accumulate in the sympathetic nerve endings. This review includes a brief description of norepinephrine metabolism and pharmacokinetics of 123 I-MIBG in the sympathetic nerve ending, a brief description of the study methodology and the clinical significance of this method in patients with heart failure. Particular attention is paid to the possibilities of using this method in patients with severe chronic heart failure before and after CRT.

Prediction of Cardiac Resynchronization Therapy Response in Dilated Cardiomyopathy Using Vortex Flow Mapping on Cine Magnetic Resonance Imaging

Background: We investigated the association between left ventricle ejection fraction (LVEF) and vortex flow (VF), and whether cardiac resynchronization therapy (CRT) response can be predicted using VF mapping (VFM) in patients with dilated cardiomyopathy (DCM).

Methods and Results: Cardiac magnetic resonance imaging data for 20 patients with heart failure (HF) with LVEF ≥40% and 25 patients with DCM with LVEF <40%, scheduled for CRT, were retrospectively analyzed. The maximum VF (MVF) on short-axis, long-axis and 4-chamber LV cine imaging were calculated using VFM. Summed MVF was used as a representative value for each case and was significantly greater for patients with DCM than for patients with HF with LVEF ≥40% (25.2±19.2% vs. 12.1±15.4%, P<0.005). Summed MVF was significantly greater for CRT responders (n=12, 35.8±22.7%) than for non-responders (n=13, 15.8±8.7%, P=0.04) during the mean follow-up period of 38.4 months after CRT. Patients with summed MVF ≥31.3% had a significantly higher major adverse cardiac event-free rate than those with MVF <31.3% (log-rank=4.51, P<0.05).

Conclusions: On VFM analysis, LV VF interrupted efficient ejection in HF. Summed MVF can predict CRT response in DCM.

Structural changes in Parkinson's disease: voxel-based morphometry and diffusion tensor imaging analyses based on 123I-MIBG uptake

OBJECTIVE

Patients with Parkinson's disease (PD) may exhibit symptoms of sympathetic dysfunction that can be measured using ¹²³I-metaiodobenzylguanidine (MIBG) myocardial scintigraphy. We investigated the relationship between microstructural brain changes and ¹²³I-MIBG uptake in patients with PD using voxel-based morphometry (VBM) and diffusion tensor imaging (DTI) analyses.

METHODS

This retrospective study included 24 patients with PD who underwent 3 T magnetic resonance imaging and ¹²³I-MIBG scintigraphy. They were divided into two groups: 12 MIBG-positive and 12 MIBG-negative cases (10 men and 14 women; age range: 60-81 years, corrected for gender and age). The heart/mediastinum count (H/M) ratio was calculated on anterior planar ¹²³I-MIBG images obtained 4 h post-injection. VBM and DTI were performed to detect structural differences between these two groups.

RESULTS

Patients with low H/M ratio had significantly reduced brain volume at the right inferior frontal gyrus (uncorrected p < 0.0001, K > 90). Patients with low H/M ratios also exhibited significantly lower fractional anisotropy than those with high H/M ratios (p < 0.05) at the left anterior thalamic radiation, the left inferior fronto-occipital fasciculus, the left superior longitudinal fasciculus, and the left uncinate fasciculus.

CONCLUSIONS

VBM and DTI may reveal microstructural changes related to the degree of ¹²³I-MIBG uptake in patients with PD.

KEY POINTS

• Advanced MRI methods may detect brain damage more precisely. • Voxel-based morphometry can detect grey matter changes in Parkinson's disease. • Diffusion tensor imaging can detect white matter changes in Parkinson's disease.

Geometrical characteristics of left ventricular dyssynchrony in advanced heart failure. Myocardial strain analysis by tagged MRI

The aims of this study were to quantify the geometrical differences in left ventricular (LV) dyssynchrony in patients with heart failure (HF) using cine-tagged MRI, and to investigate the relationship between dyssynchrony and major adverse cardiac events (MACE) in HF.In 67 patients with HF [mean LV ejection fraction (LVEF), 34%], cardiac MRI using a 3-Tesla scanner was performed. The dyssynchrony time between septal and lateral segments (SL-DT) and between basal and apical segments (BA-DT) was computed by cross-correlation analysis of the strain time-curves from the cine-tagged MRI. After receiving optimal medical treatment, all patients were followed-up for a mean period of 27 months. The primary endpoint was MACE that consisted of cardiac death or HF hospitalization or a left ventricular assist device due to refractory pump failure. Multivariate logistic regression analysis was performed to determine the ability of SL-DT, BA-DT, and HF biomarkers to predict MACE.Multivariate logistic regression analysis showed that the odds ratio to predict MACE was 0.935 for LVEF (P = 0.021), 1.016 for BA-DT (P = 0.026), and 0.971 for systolic blood pressure (P = 0.126).The results show that basal-apical dyssynchrony is an independent predictor of MACE in HF patients.

Interventricular Dyssynchrony Using Tagging Magnetic Resonance Imaging Predicts Right Ventricular Dysfunction in Adult Congenital Heart Disease

PURPOSE

Right ventricular (RV) failure and ventricular dyssynchrony are strong determinants of prognosis in patients with adult congenital heart disease (ACHD). The aim of this study was to investigate the relationship between interventricular dyssynchrony (IVD) using cine-tagged magnetic resonance imaging (MRI) and RV dysfunction in ACHD patients.

MATERIALS AND METHODS

Sixty-seven patients with ACHD (38 with repaired tetralogy of Fallot; 22 with atrial septal defect; seven with ventricular septal defect) underwent tagging MRI. Time curves of myocardial circumferential strains for RV and left ventricular (LV) free walls were delivered from short-axis cine-tagging images. Contraction delay between RV and LV free walls was computed by cross-correlation analysis of the two strain time curves and was defined as the IVD time (msec).

RESULTS

IVD was significantly greater for patients with RV ejection fraction (RVEF) <40% (116 ± 58 msec) than for patients with RVEF ≥ 40% (65 ± 54 msec) and was significantly greater for patients with RV systolic pressure ≥ 40 mm Hg (112 ± 59 msec) than for patients with RV systolic pressure <40 mm Hg (49 ± 28 msec). Receiver operating characteristic analysis revealed optimal IVD thresholds for detecting patients with RVEF <40% with C-statistics of 0.76 and patients with RV systolic pressure ≥ 40 mm Hg with C-statistics of 0.81.

CONCLUSION

Quantification of IVD was possible using RV and LV strains derived from tagging MRI. IVD, represented as the time difference between LV and RV contractions, correlates with RV dysfunction. IVD may thus offer an indicator for RV failure in ACHD.