P15 The characterisation and investigation of pulmonary arteriovenous malformations and cerebral abscess risk factors within a rare vascular disease: results from a targeted 125-question, international patient survey

Introduction and objectives Hereditary Haemorrhagic Telangiectasia (HHT) is an autosomal dominant vascular disorder characterised by epistaxis, telangiectasia, and arteriovenous malformations (AVMs). Approximately half of individuals have pulmonary AVMs (PAVMs), the subject of a recent British Thoracic Society Clinical Statement. 1 The latest data suggest 1 in 15 UK patients with PAVMs suffer a life-changing cerebral abscess. 2 This study aims to characterise individuals with PAVMs and investigate both novel and newly-identified cerebral abscess risk factors. 2 Method With ethical approval, an international, online questionnaire comprising 125 non-biased questions was designed and advertised through global HHT networks. The questions focused on an individual’s HHT and PAVM phenotype, and abscess-relevant factors including the dental source of abscess bacteria, long-standing recommendations to use antibiotic prophylaxis prior to dental/surgical procedures, and other possible risk factors. 2 Data responses were evaluated using R. Results 518 participants with self-reported HHT responded. 465 provided online consent and passed inbuilt validity tests. 320/465 (68.8%) were female. 232 respondents (49.9%) had PAVMs which were diagnosed due to family history (n=53), a preceding medical event (n=37) or as an incidental finding (n=40). 163/232 (70.3%) had embolization/surgery as treatment for their PAVMs. 17/232 (7.3%) individuals had cerebral abscesses. There was poor compliance with antibiotic prophylaxis guidance. 1 Only 52.8% always took antibiotics prior to the dentist, and 40.6% had attended without antibiotics. Worryingly, 11.4% were unaware of the recommendation. The overall burden of cerebral complication in this cohort was significant: 139/465 (29.9%) described a family member with a cerebral abscess (n=59) or cerebral haemorrhage. 15 (25.4%) of the relatives died due to their abscess. Conclusions This survey provided a large dataset from individuals with HHT and PAVMs and confirm that cerebral abscesses remain a significant PAVM complication. There was a concerning lack of patient and clinician knowledge about abscess risk and association with odontogenic bacteria. These preliminary results demonstrate a need for better prediction tools in abscess risk reduction. References British Thoracic Society Clinical Statement on Pulmonary Arteriovenous Malformations.ThoraxDecember 2017;72(12):1154–63. Boother EJ, Brownlow S, Tighe HC, Bamford KB, Jackson JE, Shovlin CL. Cerebral abscess associated with odontogenic bacteremias, hypoxemia, and iron loading in immunocompetent patients with Right-to-Left shunting through pulmonary arteriovenous malformations. Clin Infect Dis2017;65(4):595–603.