Temporal order of atrial fibrillation and acute myocardial infarction and associated prognosis in the Danish Diet, Cancer, and Health cohort

Abstract Background Atrial fibrillation (AF) and acute myocardial infarction (AMI) share risk factors and are bidirectionally associated. Several studies found higher risks of outcomes in individuals with both conditions. Whether the risks of outcomes differ according to temporal order of AF and AMI is unclear. Purpose We aimed to assess the risks of heart failure (HF), ischemic stroke (IS) and all-cause mortality in individuals with both AF and AMI compared to only one. In addition, we assessed risks of outcome according to the temporal order of AF and AMI in individuals with both conditions. Methods The study was based on the Danish Diet, Cancer and Health cohort in which 57,053 men and women aged 50-64 years, with no diagnosis of cancer, participated. Assessment of AF, AMI and outcomes were based on diagnosis codes from the Danish National Patient Registry. We examined the risks of HF, IS and all-cause mortality during 10 years of follow-up in participants with both AF and AMI compared to only one and according to the temporal order of AF and AMI in participants with both conditions using Cox regression models. Results We identified 5,816 participants with newly diagnosed AF only, 3,448 with first AMI only, 348 with AF before AMI and 721 participants with AMI before AF. The multivariable-adjusted risks of HF, IS and all-cause mortality were higher among participants with both AF and AMI compared to participants with only AF or AMI (Figure 1). In participants with both AF and AMI, there was no difference in risk of HF (HR=0.92, 95% CI 0.72-1.17) or IS (HR=1.12, 95% CI 0.76-1.66) between participants with AF before AMI compared to AMI before AF. AMI before AF was associated with lower all-cause mortality compared to AF before AMI (HR=0.70, 95% CI 0.54-0.90) (Figure 2). Conclusions Risks of adverse outcomes were higher among participants with both AF and AMI compared to only AF or AMI. All-cause mortality, but not risk of HF or IS, differed according to temporal order with a lower mortality among participants with AMI before AF.Figure 1Figure 2