Background Acute coronary syndrome (ACS) and other cardiovascular diseases are the main drivers of the increased morbidity and preterm mortality in rheumatoid arthritis (RA). ACS in RA has been linked to inflammation and RA severity. During recent years and with new therapeutic options and treat-to-target strategies, increasing efforts have been made to reach RA remission as soon as possible after diagnosis, and the average level of RA disease activity has declined. Whether this has resulted in declining excess risks for RA comorbidities remains unclear.

Methods We performed a nationwide population-based cohort study of patients with new-onset RA from 1997 to 2014, and matched general population comparators. In the Swedish healthcare system, all residents have equal access to healthcare services. Healthcare is monitored using high-quality population-based registers that can be linked together. 15 744 patients with new-onset RA, identified from the Swedish Rheumatology Quality Register, and 70 899 general population comparator subjects were included.

Results Seven hundred and seventy two patients with RA developed an ACS during 103 835 person-years of follow-up (crude incidence, 7.4 per 1000), corresponding to an overall HR versus the general population of 1.41 (95% CI 1.29 to 1.54). Whereas the ACS incidence declined over calendar time in both the RA and the general population cohort, the excess and the relative risks of ACS remained the same.

Conclusions Despite improved disease control in new-onset RA, the elevated risk of ACS in RA remains a concern.