Sex-specific longitudinal changes in resting heart rate and new-onset atrial fibrillation: insights from the HUNT Study

Aims To investigate associations between longitudinal changes in resting heart rate (ΔRHR) and new-onset atrial fibrillation (AF) among Norwegian women and men. Methods We included 47,234 adults attending two or three Trøndelag Health Study surveys (1995–2017). Associations with AF were assessed for ΔRHR and joint baseline-ΔRHR categories, and continuous ΔRHR using restricted cubic splines. Cox models were used to estimate adjusted hazard ratios (HR) and 95% confidence intervals (CIs). Results During follow-up, 4,614 participants developed AF. Women had a lower incidence rate than men (6.41 vs. 10.02 per 1,000 person-years; incidence rate ratio 0.64, 95% CI 0.60–0.68). Compared with maintained ΔRHR, decreased and increased ΔRHR (>12 bpm) were associated with 21% and 33% higher AF risk in women, respectively, while increased ΔRHR was associated with 17% higher risk in men. Restricted cubic splines indicated a J-shaped ΔRHR-AF association in women, but not in men. In joint baseline-ΔRHR analyses, low baseline RHR combined with maintained or increased ΔRHR was associated with higher AF risk in both sexes. Among women, both decreased and increased ΔRHR were associated with higher AF risk at moderate baseline RHR, whereas only increased ΔRHR remained associated with AF at high baseline RHR (92% higher risk). No corresponding pattern was observed in men. Conclusion ΔRHR showed sex-specific associations with AF risk. In women, risk was lowest with moderate baseline RHR and a maintained ΔRHR, and higher with both decreased and increased ΔRHR. In men, higher AF risk was primarily observed among those with low baseline RHR.