252. Myocardial infarction in ANCA-associated vasculitis- a population-based cohort-study

Objectives: To determine the incidence rate (IR) and predictors of acute myocardial infarction (MI) in patients with ANCA-associated vasculitis (AAV). Methods: This population based retrospective cohort study included 325 patients diagnosed with AAV between 1997 and 2016 in a defined population in southern Sweden. To identify patients diagnosed with MI, the AAV cohort was linked to the SWEDEHEART registry, a national quality of care registry including all MI-cases hospitalized at coronary care units in Sweden, and to the Skåne Healthcare register (SHR), a regional diagnosis database. Cases found in SHR but not included in SWEDEHEART were confirmed via case record review. Demographics and clinical data were collected from time of AAV diagnosis. MI events occurring in a period beginning 3 months prior to AAV diagnosis and any time after were considered AAV-related MI. For each patient with AAV, we randomly sampled 10 age and sex-matched controls from the background population. The incidence rate (IR) of AAV- related first MI was calculated dividing cases by sum of person years of follow up. Follow up time was defined as time from diagnosis of AAV (index-date for controls assigned as same as date of AAV-diagnosis in AAV-partner) to first MI-event, death, or end of study in November 2018. The incidence rate ratio (IRR) was calculated by dividing the IR for patients with AAV by the corresponding rate for the controls. Predictors of MI in AAV was studied using Cox-regression model using the following factors in uni- and multivariable analysis: age at AAV diagnosis, disease phenotype, creatinine per 100 μmol/L increase and ENT-involvement. Results: Thirty-seven patients (11.4%) were diagnosed with a first time AAV-related MI during a follow up time of 2330 person-years. The IR of MI was 1.6/100 person-years (95% CI 1.1-2.1). Compared to official Swedish statistics, the AAV- patients of this cohort were more than five times as likely to suffer a MI compared to the overall adult population. The IR was highest within three months from AAV diagnosis, 10.2/100 person-years (95% CI 3.1-17.2). The IRR of MI was 1.9 (95% CI 1.3-2.8, p=0.001). The highest IRR were obtained for patients with MPO-ANCA+ disease (2.5, 95% CI 1.5-4.3, p=0.0004), and those with BVAS >15 at time of AAV-diagnosis (2.1, 95% CI 1.3-3.3, p=0.002). Age at AAV diagnosis independently predicted occurrence of MI. Conclusions: This cohort study shows that patients with AAV are more prone to suffer from MI, particularly within the first period after disease onset. Age was the single independent predictor of MI in AAV-patients