30-year nationwide trends in incidence of atrial fibrillation in Denmark and associated 5-year risk of heart failure, stroke, and death.

Background: Long-term nationwide trends in atrial fibrillation (AF) incidence and 5-year outcomes are rare.

Methods: We conducted a population-based cohort study using the Danish National Patient Registry covering all Danish hospitals. We computed standardized incidence rates during 1983-2012. We used Cox regression to estimate hazard ratios (HRs) of heart failure, stroke, and death within 5years, comparing 5-year calendar periods with the earliest period (1983-1987) as reference.

Results: We identified 312,420 patients with first-time hospital-diagnosed AF. The incidence rate per 100,000person-years increased from 98 in 1983 to 307 in 2012. The mean annual increase during the 30-year study period was 4%, with a 6% increase annually until 2000 and a 1.4% increase annually thereafter. The incidence trends were most pronounced among men and persons above 70years. Among high-risk subgroups, AF incidence was consistently highest in patients with valvular heart disease or heart failure. The rate of heart failure following AF declined by 50% over the entire study period (HR: 0.49, 95% confidence interval (CI): 0.48-0.51) and the mortality rate declined by 40% (HR: 0.62, 95% CI: 0.61-0.63). Within the last two decades, the rate for ischemic stroke declined by 20% (HR 0.81, 95% CI: 0.78-0.84), but increased almost as much for haemorrhagic stroke (HR: 1.14, 95% CI: 1.01-1.29).

Conclusions: The long-term risk of heart failure, ischemic stroke, and death following onset of AF has decreased remarkably over the last three decades. Still, the threefold increased incidence of hospital-diagnosed AF during the same period is a major public health concern.