P35 A retrospective observational study designed to characterise individuals with pulmonary Arteriovenous Malformations (PAVMS) and cerebral abscesses at a single institution

Introduction and objectives Individuals with pulmonary arteriovenous malformations (PAVMs), who often concurrently have hereditary haemorrhagic telangiectasia (HHT), are at increased risk of cerebral abscess, frequently resulting in life-changing deficits. Current aetiological consensus supports paradoxical emboli of periodontal origin, with preventative dental recommendations published in 2008. 1 Limited knowledge is available to identify specifically at-risk individuals. This study aimed to characterise a cohort from 2005–2016; recognise potential precipitants; and compare results to an earlier published series. Methods With ethical approval, notes of patients newly presenting at a single institution between 2005–2016 were reviewed to collect cohort characteristics. GraphPad Prism was used to calculate descriptive statistics, and to perform Mann-Whitney and Chi-squared statistical tests for comparison between the two cohorts. Results Of 488 new patients with PAVMs, 33 (6.8%) had cerebral abscesses. 21 were female (63.6%), 12 male. The rate corrected for ascertainment bias was 3.8%. The median age at abscess was 46 years (range 13–69). The median oxygen saturation (SaO 2 ) was 90.75% (range 70–97.5%), with 9 individuals having respiratory symptoms. There were 29 confirmed HHT diagnoses (87.9%). The median largest feeding artery diameter was 5mm, and for 5 individuals, all feeding arteries had diameter ≤3 mm. In total, 19 (57.6%) had residual PAVMs too small for embolization. Organisms identified (Table 1) suggest periodontal origin; 16 individuals (48.5%) had poor dental hygiene and 9 (27.3%) had dental events as abscess precipitants. Interestingly, 4 individuals had abscesses whilst on holiday abroad. 5 individuals reported worsening migraines and 2 individuals had increased seizure frequency ≤ 3 months pre-abscess. Within the non-overlapping 1999–2005 cohort, there were 28/219 abscesses (12.8%, 9.05% adjusting for ascertainment bias). Compared to the later series, similar proportions of abscesses occurred prior to PAVM diagnosis (18/28 (64.3%) vs. 24/33 (72.3%)). Proportionally more males were affected (57.1%). No other significant differences were found for age, SaO 2 , feeding artery diameter, presence of respiratory symptoms, or HHT (all p values >0.12). Conclusion The PAVM cohort remains at high risk of cerebral abscess. Scrupulous dental hygiene appears to remain paramount to reduce risk. The worsening migraines and abscess occurrence whilst abroad are unexpected findings recommended for further investigation. Reference Shovlin C, et al . Post-NICE 2008: Antibiotic prophylaxis prior to dental procedures for patients with pulmonary arteriovenous malformations (PAVMs) and hereditary haemorrhagic telangiectasia. Br Dent J 2008; 205 (10):531–3.