Cardio-pulmonary involvement in pulmonary arterial hypertension: A perfusion and innervation scintigraphic evaluation

BACKGROUND

Pulmonary arterial hypertension (PAH) is characterized by the right ventricle (RV) remodeling and pulmonary endothelial dysfunction. We studied cardiac perfusion and innervation in PAH with a cadmium-zinc-telluride (CZT) scanner and lung uptake impairment of 123I-metaiodobenzylguanidine (123I-MIBG).

METHODS

In 13 patients with newly diagnosed PAH and 11 dilated cardiomyopathies (DCM, for comparative purposes), we assessed early and delayed 123I-MIBG uptake ratios of lung-to-mediastinum (L/M) and heart-to-mediastinum (H/M) on anterior planar images. A quantitative myocardial innervation with 123I-MIBG and perfusion with 99mTc-tetrofosmin using CZT-SPECT was performed. All patients underwent right heart catheterization.

RESULTS

Early and delayed L/M ratios in PAH were lower than DCM (1.47 ± 0.14 vs 1.98 ± 0.11 and 1.40 ± 0.13 vs 1.83 ± 0.09; P < .001), while early and delayed H/M were impaired but not different (1.73 ± 0.20 vs 1.65 ± 0.18 and 1.73 ± 0.27 vs 1.58 ± 0.19). RV perfusion and early innervation were significantly higher in PAH compared to DCM (68.4 ± 13.4 vs 28.6 ± 4.1 and 58.8 ± 9.3 vs 27 ± 2.2; P < .001); delayed RV innervation was not evaluable. RV/LV perfusion and innervation ratios were significantly related (R = 0.74; P < .0001) and had a significant correlation with clinical, hemodynamic, and morpho-functional parameters, including L/M ratios.

CONCLUSION

Cardio-pulmonary scintigraphy through a perfusion and innervation study is feasible and may identify pulmonary vascular and RV remodeling, as in PAH.

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.

The potential for early diagnosis of pulmonary arterial hypertension using lung iodine-123-metaiodobenzylguanidine (123I-MIBG) uptake: A case report

Previous reports have found evidence that the lung uptake of iodine-123-metaiodobenzylguanidine (¹²³I-MIBG) represents pulmonary vascular endothelial function. Therefore, it was believed that the reduced lung uptake of ¹²³I-MIBG in patients with pulmonary artery hypertension may indicate poor pulmonary vascular endothelial function in those patients. In our previous report, we analyzed the lung uptake of ¹²³I-MIBG in patients with pulmonary hypertension, and demonstrated that it is lower in patients with pulmonary arterial hypertension (PAH) than in those with chronic thromboembolic pulmonary hypertension and controls, suggesting that reduced uptake of ¹²³I-MIBG in patients with PAH indicates endothelial dysfunction of the pulmonary artery. In the current report, we describe a 46-year-old woman diagnosed with scleroderma whose lung uptake of ¹²³I-MIBG was decreased on admission, but she was not diagnosed with pulmonary artery hypertension at that time because her pulmonary artery pressure during right heart catheterization was not elevated. However, she was diagnosed with borderline PAH 2 years later. The lung uptake of ¹²³I-MIBG was reduced before a reduction in %DLCO was observed. This report suggests that the lung uptake of ¹²³I-MIBG may be useful for the early diagnosis of pulmonary artery hypertension.