A Study to Assess Changes in Lung Perfusion Scan with Clinical and Haemodynamic Outcome in Patients Undergoing Pulmonary Thromboendarterectomy for CTEPH

Abstract

Purpose CTEPH is defined as pulmonary hypertension in a patient with pulmonary thromboembolic after receiving at least three months of therapeutic anticoagulation, and as such leads to significant morbidity and mortality. Pulmonary Thromboendarterectomy is an established treatment option in CTEPH patient . While a Ventilation-Perfusion scan is preferred over CTPA in establishing the diagnosis of CTEPH, there is limited information available about the role and timing of Lung perfusion scan post-Pulmonary Thromboendarterectomy. In this study, we studied Lung perfusion scan changes post PTE surgery besides clinical and echocardiography parameters. Methods Retrospective single centre observational study of patients who underwent Lung perfusion scan before and after pulmonary PTE surgery between January 2017 and May 2019. Perfusion defect was calculated based on scoring system where large defect was given score 3, medium defect = 2, small defect =1 and no defect = 0. Final perfusion defect score was obtained taking in account total of 19 segments (10 on right lung and 9 on left lung). Results A total of 58 patients with CTEPH who underwent PTE surgery were studied. Out of whom, 74.1% (n=43) were males and 25.9% (n=15) were females. The median age of study population was 39.5 years (IQR 17-65). There was significant improvement in mean 6 MWD (366.36±86.77m to 454.34±71.23m as well as decrease in right atrial (48.91±7.46 to 34.96±4.77 mm), right ventricular diameter (41.61±6.63 to 28.60±3.94 mm) after PTE surgery in our study. Majority of 41.4% (N=24) patients underwent perfusion scan between 3 to 6 month after PTE surgery and 47.1 %( N=27) patients showed more than 75% improvement in perfusion score after PTE surgery. Median lung perfusion defect score decreased to 8.0 postoperatively in comparison to 28.5 preoperatively (p=0.002). Additionally, 37.9 %( N=21) patient developed new perfusion scan defect on follow up scan. Conclusion Postoperative Lung perfusion scan showed significant enhancement in perfusion after successful PTE surgery in addition to substantial improvement in clinical and hemodynamic parameters. Nevertheless, new perfusion defects were noted in a small subset of patients in our study, which could represent either vascular steal phenomenon or new thromboembolic episode.