Aims: The incidence of atrial fibrillation (AF) has increased significantly over the last decades. Population height is changing in many countries. Height is an important risk factor for AF. The aim of the present study was to assess the role of changes in population height in the increased risk of AF.

Methods and results: The Copenhagen City Heart Study comprises 18 852 randomly selected men and women aged 20-93 years, studied in four separate cross-sectional surveys in 1976-78, 1981-83, 1991-94, and 2001-03, including physical examination, electrocardiogram (ECG), and standard questionnaires. Hospitalization and mortality data were collected from public registers. Prevalent AF was determined from ECGs and incident AF from register diagnoses. During follow-up, age-standardized prevalence of AF increased significantly from 1.35% to 2.11% in men and from 0.67% to 1.07% in women (P < 0.001). Incident AF increased four-fold in both men and women [hazard ratio (HR) 4.16, 95% confidence interval (CI) 3.27-5.29; P < 0.001]. In multivariable Fine and Gray subdistribution hazards regression analyses, height was consistently an important risk factor for incident AF with HRs between 1.35 (95% CI 1.10-1.66; P = 0.004) and 1.65 (95% CI 1.40-1.93; P < 0.001). Population height increased with 3.3 cm for men and 2.1 cm for women, and population attributable risks for height was 20-30%.

Conclusion: Height is a powerful risk factor for AF. Adult height is attained at age 20, while AF incidence occurs 50 years later. Given a causal relationship between height and AF incidence, increased population height in Denmark will contribute to an increase in AF occurrence for at least 25 more years.