Chronic thromboembolic pulmonary hypertension in Australia and New Zealand: An analysis of the PHSANZ registry.

BACKGROUND AND OBJECTIVE: Chronic thromboembolic pulmonary hypertension (CTEPH) is a serious condition occurring in 2%-4% of patients after acute pulmonary embolism. Pulmonary endarterectomy (PEA) is a potential cure for technically operable disease. The epidemiology and long-term outcomes of CTEPH have not been previously described in Australia and New Zealand. METHODS: Data were extracted from the Pulmonary Hypertension Society of Australia and New Zealand (PHSANZ) registry for patients diagnosed with CTEPH between January 2004 and March 2020. Baseline characteristics, treatment strategies, outcome data and long-term survival are reported. RESULTS: A total of 386 patients were included with 146 (37.8%) undergoing PEA and 240 (62.2%) in the non-PEA group. PEA patients were younger (55 ± 16 vs. 62 ± 16 years, p < 0.001) with higher baseline 6-min walk distance (6MWD; 405 ± 122 vs. 323 ± 146 m, p = 0.021), whilst both groups had similar baseline pulmonary haemodynamics. Pulmonary hypertension-specific therapy was used in 54% of patients post-PEA and 88% in the non-PEA group. The 1-, 3- and 5-year survival rates were 93%, 87% and 84% for the PEA group compared to 86%, 73% and 62%, respectively, for the non-PEA group (p < 0.001). Multivariate survival analysis showed baseline 6MWD was an independent predictor of survival in both operated and medically managed patients. CONCLUSION: In this first multicentre report of CTEPH in Australia and New Zealand, long-term survival is comparable to that in other contemporary CTEPH registries. However, PEA was only performed in a minority of CTEPH patients (37.8%) and significantly less than overseas reports. Greater awareness of PEA and improved patient access to experienced CTEPH centres are important priorities.

Pulmonary hypertension leads to a loss of gravity dependent redistribution of regional lung perfusion: a SPECT/CT study.

OBJECTIVE: Pre-capillary pulmonary hypertension (PHT) is characterised by progressive pulmonary vascular obliteration and loss of vascular reserves. In health, regional lung perfusion redistributes under the influence of gravity due to the presence of recruitable vessels. We investigated a combined single photon emission computed tomography/CT (SPECT/CT) method for assessing the pulmonary circulation by quantifying the gravity dependent redistribution of lung perfusion. DESIGN: Characterisation of patients versus healthy controls. PATIENTS: 15 patients with pre-capillary PHT and 11 healthy controls. SETTING: University hospital clinic. INTERVENTION: Regional lung perfusion was measured using SPECT/CT in two different postures (supine vs upright). A perfusion redistribution index (PRI) was used to quantify the cranial-caudal shift in regional lung perfusion resulting from gravitational (postural) change. MAIN OUTCOME MEASURE: PRI was compared between cases and controls, and correlated with markers of disease severity in cases. RESULTS: Patients with pre-capillary PHT had notably reduced PRI compared to controls (0.02±0.06 vs. 0.28±0.15 normalised perfusion/cm, p<0.0001). PRI was significantly associated with prognostic parameters such as 6 min walk distance (r=0.60, p=0.018), functional class (p=0.008), and tricuspid annular plane systolic excursion (r=0.58, p=0.022). The receiver operating characteristic curve showed that PRI differentiated patients with pre-capillary PHT from controls with AUC=0.94 (p<0.001). CONCLUSIONS: With SPECT/CT, gravity dependent redistribution of lung perfusion can be quantified using the PRI derived from supine and upright perfusion analysis. The potential utility of PRI for the non-invasive detection of PHT and assessment of disease severity warrants further study.