The effect of semi-quantitative and quantitative analysis of SPECT V/Q scan on the efficacy of pulmonary endarterectomy in treatment of CTEPH and predicting postoperative residual pulmonary hypertension

Introduction: Pulmonary endarterectomy (PEA) is the definitive treatment for chronic thromboembolic pulmonary hypertension (CTEPH), providing excellent short-term and long-term outcomes. However, although most patients benefit from PEA, residual pulmonary hypertension (rPH) is present in 16% to 51% of post-PEA patients, and is associated with significant morbidity and mortality. In this study, we assessed the effect of SPECT V/Q imaging on the efficacy of PEA in patients diagnosed with CTEPH. We also summarized the characteristics associated with the preoperative imaging in patients with rPH after surgery to determine what kind of patients could benefit from the surgery and which patients did not show improvement in pulmonary arterial pressure following surgery.

Methods: Patients with CTEPH who underwent PEA and received pre- and post-operative right heart catheterization (RHC) and SPECT V/Q scans were studied retrospectively. The characteristics of the pre-operative V/Q images from patients with rPH were summarized.

Results: Twenty-four patients were enrolled. The parameters of SPECT V/Q scans, including the number of mismatched segmental perfusion defects, Begic's scores, the volume percentage of mismatched defects calculated using HERMES Hybrid 3D-Lung Lobar Quantification software and the NYHA classification, the six-minute walk distance (6MWD), and RHC-associated parameters [systolic pulmonary arterial pressure (sPAP) and mean pulmonary arterial pressure (mPAP)] exhibited significant improvement after PEA (Table 1). rPH was present in nine patients (37.5%), who exhibited a shorter 6MWD, higher levels of the NYHA classification, and larger Begic’s scores and volume percentages of mismatched V/Q scans than patients without rPH (Table 2).

Table 1. Comparison of pre- and post-operative clinical information, RHC-associated parameters and parameters of SPECT V/Q scans.

Table 2. Pre-operative characteristics of clinical, hemodynamic, and SPECT V/Q parameters in patients with and without rPH after PEA surgery.

Conclusions: The pulmonary perfusion images obtained with SPECT V/Q scan improved significantly after PEA. Quantitative analysis of V/Q scans could provide complementary information that allowed better prediction of postoperative rPH than qualitative analysis.