Long-term rate of ventricular arrhythmia in autoimmune disease

Aims Although selected autoimmune diseases (AIDs) have been linked to an increased risk of ventricular arrhythmias (VAs), data on the long-term rate of VAs across the spectrum of AIDs are lacking. The aim of this study was to investigate the long-term rate of VAs (a composite of ventricular tachycardia, ventricular fibrillation, ventricular flutter, or cardiac arrest) in individuals with a history of 28 different AIDs. Methods and results Individuals diagnosed with an AID (2005-18) were identified through Danish nationwide registries. Each patient with an AID was matched with four individuals from the background population by age and sex. Multivariable Cox regression was used to compare the rate of VAs between the AIDs and background population, overall and according to individual AIDs. In total, 186 733 patients diagnosed with AIDs were matched with 746 932 individuals without AIDs (median age 55 years; 63% female; median follow-up 6.0 years). The 5-year cumulative incidence of VAs was 0.5% for patients with AIDs and 0.3% for matched individuals. Patients with any AIDs had a higher associated rate of VAs than matched individuals {hazard ratio (HR) 1.39 [95% confidence interval (CI), 1.29-1.49]}. The highest HR was observed in patients with systemic sclerosis [3.86 (95% CI, 1.92-7.75)]. The higher rate of VAs in patients with AIDs, compared with individuals from the background population, was more pronounced in patients without ischaemic heart disease or heart failure/cardiomyopathy compared with those with these conditions (P-interaction <0.05). Conclusion Despite a low cumulative incidence, patients with a history of AIDs had a higher relative rate of VAs than matched individuals.