Abstract No. 519 Retreatment of Persistent Pulmonary Arteriovenous Malformations: Technical Factors that Influence Long-Term Durable Occlusion

Pulmonary arteriovenous malformations (PAVMs) can persist after embolization 25-49% of the time. The reason for treatment failure is not well understood. This study examines a cohort of recanalized (flow through previous embolic treatment) or reperfused (flow through a recruited feeding vessel) PAVMs, including primary treatment characteristics, retreatment techniques and outcomes of repeat embolization. This study retrospectively reviewed 19 patients who underwent 24 consecutive PAVM embolization procedures for persistent PAVMs with follow-up cross-sectional imaging at a single center between August 2014 and January 2022. Characteristics of the PAVMs were collected including simple vs complex, saccular vs non-saccular, primary embolic material, embolization of the nidus, type of persistence, retreatment data and reperfusion/recanalization on follow-up imaging. The success of repeat treatment was assessed on follow-up imaging. Chi-square test was used to compare groups. Median patient age was 59 (range 9-71) and 42% were male. Seven patients with 10/24 (42%) PAVMs were primarily treated at an outside institution. Most PAVMs were simple (71%), saccular (71%) and primarily treated with coils (88%), rather than plug (4%) or coils and plug (8%). The nidus was primarily treated in only 4/24 (17%). Primary treatment recanalization was seen in 15/24 (62%), reperfusion in 7/24 (29%) and both in 2/24 (8%). Retreatment was performed with non-fibered coils (42%), fibered coils (29%), AVP and coils (21%) or Onyx (8%). Retreatment technical failure was 4/24 (7%) and an additional 3/24 (12%) reperfused on follow-up. Thus, 7/24 (29%) PAVMs had persistent flow on follow-up imaging with median follow-up of 31 months. Retreatment embolization into the nidus through the existing embolic or via a recruited vessel was achieved in 11/24 (46%). None of these demonstrated persistence on follow-up; however, there was persistence when the nidus was not treated (7/13, 54%), (p=0.005). No correlation was seen between PAVM persistence and prior recanalization (p=0.68), prior reperfusion (p=0.54), simple (p=0.68) or saccular PAVM (p=0.68), retreatment with non-fibered coils (p=0.26), fibered coils (p=0.36) or AVP (p=0.54). No major procedural complications occurred. Retreatment of persistent PAVMs can achieve a high rate (83%) of technical success. Embolization of the nidus either through the existing embolization material or via a recruited pulmonary vessel with coils, plugs or liquid embolic can achieve high long-term occlusion.