Detection of Residual Pulmonary Vascular Obstruction by Ventilation-Perfusion Lung Scan Late After a First Pulmonary Embolism

Abstract The long-term impact of persistent pulmonary vascular obstruction after pulmonary embolism (PE) remains unknown. Based on ventilation-perfusion (V-Q) lung scan performed at discharge and 3 months after a first pulmonary embolism (PE), we aimed to investigate the prognostic value on 5-year adverse events of (1) residual pulmonary vascular obstruction (RPVO) at discharge (DIS-RPVO), (2) RPVO at 3 months (3M-RPVO), and (3) relative change in RPVO between the two scans (RC-RPVO). We performed a prospective, multicenter cohort study from 01/2007 to 12/2009 including patients who survived at least 3 months after a PE. RC-RPVO was defined as (DIS-RPVO – 3M-RPVO)/DIS-RPVO. The primary endpoint was a combined endpoint at 5 years, composed of all-cause death, recurrent venous thromboembolism, chronic thromboembolic pulmonary hypertension, heart failure and rehospitalization for cardiac causes. Receiver-operating characteristic curves were computed to define thresholds of DIS-RPVO, 3M-RPVO and RC-RPVO predictive of the primary combined end-point at 5 years. Overall, 241 patients were included (high-risk PE:11.2%, intermediate-risk PE:51.8%, low-risk PE:37%). Mean DIS-RPVO was 27.9±15.1%, mean 3M-RPVO was 10.3±10.8% and mean RC-RPVO was 61.7±33.4%. At 5 years, 112 patients (46.5%) experienced the combined end-point. Both 3M-RPVO≥15% and RC-RPVO≤37.5% were independently related to the occurrence of the combined end-point at 5 years (p=0.01 and, p=0.02, respectively). DIS-RPVO did not predict long-term adverse events. In conclusion, RC-RPVO≤37.5% and 3M-RPVO≥15% were independently related to the occurrence of adverse events 5 years after a first PE.