Risk of ischemic and non-ischemic heart failure in patients with systemic sclerosis: a population-based study

To investigate the risk of incident ischemic and non-ischemic heart failure (HF) in a population-based cohort of all patients with systemic sclerosis (SSc) in Sweden compared to the general population. We identified patients with incident SSc 2004-2019 using nationwide Swedish registers and age- and sex-matched comparators from the general population (1:10). We started follow-up from the date of SSc diagnosis, the same date was assigned to the respective comparators. Our primary outcome was incident HF (ICD-10: I50) as main diagnosis stratified into ischemic and non-ischemic HF depending on whether a visit listing ischemic heart disease (ICD-10: I20-I25) was recorded before HF diagnosis or not. We used flexible parametric models to estimate hazard ratios (HR) over time since SSc diagnosis. The study cohort comprised 1,598 patients with SSc and 16,616 comparators. During follow-up, 101 (6%) patients with SSc developed HF compared to 378 (2%) of the comparators. Ischemic HF represented 35% and non-ischemic HF represented 65% of all HF cases in both groups. The relative risk of HF overall, ischemic HF and non-ischemic HF was highest soon after SSc diagnosis. HR at the end of the first year of follow-up was 5.7 (95% CI 4.2-7.9) for HF overall, 6.7 (95% CI 3.5-13.0) for ischemic HF, and 5.8 (95% CI 4.0-8.3) for non-ischemic HF. SSc is associated with both ischemic and non-ischemic HF, emphasizing the role of other mechanisms than ischemia, such as myocyte dysfunction, myocardial fibrosis and microvascular impairment, in the development of HF in SSc.