Glycemic control and clinical outcomes in patients with diabetes and atrial fibrillation : a nationwide cohort study

Aims: To evaluate the association of HbA1c level at the time of atrial fibrillation (AF) diagnosis with adverse outcomes (death, ischemic stroke (IS), myocardial infarction (MI), bleeding) in an unselected nationwide cohort of patients with AF and diabetes mellitus (DM). Methods: The retrospective FinACAF registry study covered all patients with incident AF in Finland between 2010 and 2017. Outcomes were analyzed using HRs and sHRs (hazard ratios and subdistribution hazard ratios), with HbA1c modelled both categorically and continuously. Results: Among 157 658 patients with incident AF, DM was present in 23% (n = 35 872). Baseline HbA1c was available in 49% (17 519) of DM patients. DM was associated with increased hazards of all evaluated outcomes. Elevated HbA1c in categorical analyses was associated with progressively increased adjusted HRs and sHRs, with highest ratios seen in HbA1c > 63 mmol/mol for death (HR 1.56, 95% CI 1.45–1.68), IS (sHR 1.38 95% CI 1.20–1.59), and MI (sHR 1.70 95% CI 1.48–1.94), when compared to patients without DM. In continuous analyses, higher HbA1c levels were associated with increasing hazards for mortality, IS, and MI. Bleeding hazards remained stable across the HbA1c spectrum. Conclusions: Higher baseline HbA1c levels were associated with progressively increased hazards of mortality, IS, and MI in patients with incident AF and DM.