BACKGROUND

In patients with acute myocardial infarction (AMI), history of atrial fibrillation (AF) and new onset AF during the early phase may be associated with a worse prognosis. Whether both conditions are associated with similar outcomes is a matter of debate.

METHODS

We collected information for all patients with AMI seen in French hospitals between 2010 and 2019. Among 797,212 patients seen with STEMI or NSTEMI, 75,701 (9.5%) had history of AF, and 34,768 (4.4%) had new AF diagnosed between day 1 and day 30 after AMI.

RESULTS

Patients with new AF were older and had more comorbidities than those with no AF but were younger and had less comorbidities than those with history of AF. During follow-up [mean (SD) 1.8 (2.4) years, median (interquartile range) 0.7 (0.1-3.1) years], 163,845 deaths and 30,672 ischemic strokes were recorded. Using Cox multivariable analysis, compared to patients with no AF, history of AF was associated with a higher risk of death during follow-up (adjusted hazard ratio HR 1.17, 95% CI 1.16-1.19) and this was also the case for patients with new AF (adjusted HR 2.11, 2.07-2.15). Both history of AF and new AF were associated with a higher risk of ischemic stroke compared to patients with no AF: adjusted HR 1.19 (1.15-1.23) for history of AF, adjusted HR 1.78 (1.68-1.88) for new AF. New AF was associated with a higher risk of death and of ischemic stroke than history of AF: adjusted HR 1.74 (1.70-1.79) and 1.32 (1.23-1.42), respectively.

CONCLUSIONS

In a large and systematic nationwide analysis, AF first recorded in the first 30 days after AMI was independently associated with higher risks of death and ischemic stroke than those in patients with no AF or previously known AF.