The significance of new onset atrial fibrillation complicating acute myocardial infarction

Background: Atrial fibrillation (AF) in the setting of acute myocardial infarction (AMI) independently predicts in-hospital and long-term morbidity and mortality. Very little data exist regarding the prognostic significance and management of new-onset AF in this setting in the era of dual anti-platelet therapy. Methods: We identified all patients admitted to our coronary care unit for AMI between 2002 and 2009 who developed new-onset AF. The control group was an age and gender matched group of AMI patients who did not have AF. Management and recurrent AF, non-fatal stroke, and mortality data were collected from subsequent hospitalizations and outpatient records. Results: Of 1,991 AMI admissions, new-onset AF was diagnosed in 100 (4.1%). Patients' age was 70 (±12), 32% were female, 58% had ST-elevation AMI and 53% had moderate or worse systolic dysfunction. AF recurred during index admission in 33%. During mean follow-up of 41 months, AF recurred in 22 and 4.5%, and non-fatal stroke occurred in 13 and 1% of the AF and control groups, respectively (p < 0.01 for both). The composite of death and non-fatal stroke was also significantly higher in the AF group, 39 versus 29% (p = 0.02). Oral anti-coagulation was used in only 24% of the AF group and was a significant predictor of stroke-free survival (p = 0.04). Conclusions: New onset AF in the AMI setting carries a substantial future risk for stroke and should not be regarded as a benign, transient complication of the acute event. Long term anticoagulation is underused and is associated with improved stroke-free survival.