A Novel Dual Energy Computed Tomography Score Correlates With Postoperative Outcomes in Chronic Thromboembolic Pulmonary Hypertension

Purpose: To compare dual-energy computed tomography (DECT) based qualitative and quantitative parameters in chronic thromboembolic pulmonary hypertension with various postoperative primary and secondary endpoints.

Materials and methods: This was a retrospective analysis of 64 patients with chronic thromboembolic pulmonary hypertension who underwent DECT. First, a clot score was calculated by assigning the following score: pulmonary trunk-5, each main pulmonary artery-4, each lobar-3, each segmental-2, and subsegmental-1 per lobe; the sum total was then calculated. The perfusion defect (PD) score was calculated by assigning 1 point to each segmental PD. The combined score was calculated by adding clot and PD scores. For quantitative evaluation, we calculated perfused blood volume (PBV) (%) of each lung and the sum of both lungs. Primary endpoints included testing association between combined score and total PBV with change in mean pulmonary arterial pressure ([mPAP], change calculated as preop minus postop values). Secondary endpoints included explorative analysis of the correlation between combined score and PBV with change in preoperative and postoperative pulmonary vascular resistance, change in preoperative 6-minute walk distance (6MWD), and immediate postoperative complications such as reperfusion edema, ECMO placement, stroke, death and mechanical ventilation for more than 48 hours, all within 1 month of surgery.

Results: Higher combined scores were associated with larger decreases in mPAP ( =0.27, P =0.036). On average, the decrease in mPAP (pre mPAP-post mPAP) increased by 2.2 mm Hg (95% CI: -0.6, 5.0) with each 10 unit increase in combined score. The correlation between total PBV and change in mPAP was small and not statistically significant. During an exploratory analysis, higher combined scores were associated with larger increases in 6MWD at 6 months postprocedure ( =0.55, P =0.002).

Conclusion: Calculation of DECT-based combined score offers potential in the evaluation of hemodynamic response to surgery. This response can also be objectively quantified.