Risk of out-of-hospital cardiac arrest in patients with rheumatoid arthritis: a nationwide study

AIM: Inflammatory cytokines in patients with rheumatoid arthritis (RA) directly affect cardiac electrophysiology by inhibiting cardiac potassium currents, leading to delay of cardiac repolarisation and QT-prolongation. This may result in lethal arrhythmias. We studied whether RA increases the rate of out-of-hospital cardiac arrest (OHCA) in the general population. METHODS: We conducted a nested case-control in a cohort of individuals between 1 June 2001 and 31 December 2015. Cases were OHCA patients from presumed cardiac causes, and were matched with non-OHCA-controls based on age, sex and OHCA date. Cox-regression with time-dependent covariates was conducted to assess the association between RA and OHCA by calculating the HR and 95% CI. Stratified analyses were performed according to sex and presence of cardiovascular diseases. Also, the association between OHCA and use of non-steroidal anti-inflammatory drugs (NSAIDs) in patients with RA was studied. RESULTS: We included 35 195 OHCA cases of whom 512 (1.45%) had RA, and 351 950 non-OHCA controls of whom 3867 (1.10%) had RA. We found that RA was associated with increased rate of OHCA after adjustment for cardiovascular comorbidities and use of QT-prolonging drugs (HR: 1.22, 95% CI: 1.11 to 1.34). Stratification by sex revealed that increased OHCA rate occurred in women (HR: 1.32, 95% CI: 1.16 to 1.50) but not in men (HR: 1.12, 95% CI: 0.97 to 1.28; P value interaction=0.046). OHCA rate of RA was not further increased in patients with cardiovascular disease. Finally, in patients with RA, use of NSAIDs was not associated with OHCA. CONCLUSION: In the general population, RA is associated with increased rate of OHCA in women but not in men.