Pos1286 arrhythmia in patients with systemic sclerosis: a swedish register-based study

Background Systemic sclerosis (SSc) is a connective tissue disease with multiple organ manifestations including cardiac involvement. Several studies have reported arrhythmias and conduction defects to be frequent in patients with SSc, however with considerable limitations such as the lack of comparison group or of stratified analyses by arrhythmia subtypes in some studies in addition to some study populations being highly selected from tertiary care centres. Objectives To explore the incidence of cardiac arrhythmias and its different subtypes in an unselected national cohort of patients with SSc compared to a matched cohort from the general population in Sweden. Methods We used nationwide Swedish registers to identify patients with incident SSc diagnosed between 2004 and 2015 in addition to comparators from the general population (1:5), matched on sex, birth year and residential area. We excluded those with a history of arrhythmia prior to start of follow-up. The primary outcome was the first ICD-coded visit indicating arrhythmia. Follow-up started from the date of SSc diagnosis, the same date was assigned to the respective comparators, until the primary outcome, death, emigration, or the end of 2016. We estimated the incidence rate of arrhythmias overall and stratified by subtype of arrhythmia in both patients with SSc and their comparators. We estimated incidence rate ratios (IRRs) using poisson regression models and time-varying hazard ratios (HRs) using flexible parametric models. Results We identified 1049 patients with SSc and 5147 matched comparators with no prior history of arrhythmia. The median follow-up was 4.7 years in patients with SSc and 5.8 years for the comparators. The incidence rate of arrhythmias overall was 216.5 per 10,000 person-years (95% CI 179.8-258.5) in patients with SSc and 106.6 (95% CI 95.5-118.7) in the comparators corresponding to IRR of 2.0 (95% CI 1.7-2.5). Table 1 demonstrates the incidence rates and IRRs stratified by arrhythmia subtypes. The HR of arrhythmia overall in patients with SSc compared to the comparators decreased gradually during follow-up; 3.0 (95% CI 2.2-4.1) at the end of the first year of follow-up, 1.9 (95% CI 1.4-2.5) at the end of the fifth year of follow-up, and 1.3 (95% CI 0.8-2.3) at the end of the 10th year of follow-up. Conclusion Patients with SSc have higher incidence rate of arrhythmia overall compared with matched comparators from the general population. Table 1. Incidence rates of arrhythmias in patients with SSc and in general population comparators, overall and stratified by arrhythmia subtypes. Incidence rate ratios are estimated using poisson regression models. Patients with SSc General population comparators Number of cases Crude incidence rate* with 95% CI Number of cases Crude incidence rate* with 95% CI Incidence rate ratio (IRR) with 95% CI All arrhythmias 122 216.5 (179.8-258.5) 335 106.6 (95.5-118.7) 2.0 (1.7-2.5 ) Conduction disorders 14 23.5 (12.9-39.5) 61 18.9 (14.5-24.3) 1.2 (0.7-2.2) Atrial fibrillation and flutter 89 154.5 (124.1-190.2) 241 75.8 (66.5-86.0) 2.0 (1.6-2.6 ) Cardiac arrest and ventricular arrhythmia 18 30.2 (17.9-47.7) 33 10.2 (7.0-14.3) 3.0 (1.7-5.3 ) Paroxysmal supraventricular tachycardia 11 18.5 (9.2-33.0) 24 7.4 (4.7-11.0) 2.5 (1.2-5.1 ) Other 20 33.7 (20.6-52.1) 40 12.4 (8.8-16.8) 2.7 (1.6-4.7 ) * per 10,000 person-years REFERENCES: NIL. Acknowledgements: NIL. Disclosure of Interests Majd Bairkdar: None declared, Zihan Dong: None declared, Pontus Andell: None declared, Roger Hesselstrand Speakers bureau: Boehringer Ingelheim and Janssen-Cilag, Employee of: Boehringer Ingelheim, Marie Holmqvist: None declared.