Pulmonary Artery Obstruction Index as a Predictor of Right Ventricular Dysfunction in Patients with Acute Pulmonary Thromboembolism: A Cross-Sectional Study

Introduction: Acute Pulmonary Thromboembolism (PTE) is a severe and often fatal venous thromboembolism that leads to haemodynamic instability due to Right Ventricular Dysfunction (RVD) and circulatory failure. Early diagnosis can reduce mortality to under 10%. Computed Tomography Pulmonary Angiography (CTPA) is the preferred imaging method, with 95% sensitivity for distal clots. The present study involving 70 PTE patients evaluated the Pulmonary Artery Obstruction Index (PAOI) as a predictor of complications. Aim: To identify the efficacy of the PAOI in predicting RVD in acute PTE patients. Materials and Methods: This cross-sectional study was conducted in the Department of Radiodiagnosis, Barnard Institute of Radiology, Rajiv Gandhi General Government Hospital, Chennai, Tamil Nadu, India between September 2023 and August 2024. The study included patients with acute PTE who showed visible thrombi on CTPA. Patients with a known history of cardiac or pulmonary diseases, those who were unable to provide consent for the study, pregnant patients, lactating mothers and patients with renal failure were excluded. CTPA was performed using a GE Revolution 128-slice Computed Tomography (CT) scanner and a Two-dimensional Echocardiography (2D Echo) was conducted with a Mindray Ultrasonography (USG) machine to compare PAOI with RVD. The Receiver Operating Characteristic (ROC) curve was used to determine the cut-off value of PAOI. The association between categorical variables and the outcomes was evaluated using Chi-square and Fisher’s-exact tests. Results: The most common PAOI score range was 41-50%, observed in 25 patients (35.80%). The right lower lobe branch was the most frequently involved pulmonary artery, affected in 61 patients (87.14%), followed by the right middle lobe artery in 52 patients (74.28%). Female patients had a higher incidence of RVD than their male counterparts. All 35 patients (50% of the study population) with RVD had a PAOI >42% (p-value <0.001), whereas 97.14% of those without RVD had a PAOI ≤42%. Conclusion: The study concluded that a PAOI >42% in thromboembolism had a sensitivity of 100% and a specificity of 97.1% for predicting RVD in patients with acute pulmonary embolism. A higher PAOI (clot burden) increases the likelihood of RVD, particularly when central arteries are involved.