Risk for Stroke in Early- vs Late-Onset Atrial Fibrillation During AMI

The occurrence of early-paroxysmal atrial fibrillation (PAF) during acute myocardial infarction (AMI) may not be associated with a higher risk for stroke, according to study results published in Angiology.

The current standard of care for patients with new-onset AF that occurs during AMI is long-term oral anticoagulant therapy.

In this retrospective analysis, the data of 7061 patients admitted to a single tertiary center for AMI were examined. Patients with a preexisting AF diagnosis, significant valvular disease, onset of AMI ≥24 hours before admission, a history of coronary artery bypass graft, fever >38.5° C, or in-hospital fatality, were excluded. A total of 6540 patients survived the index hospitalization and were divided according to AF occurrence: early-PAF (n=95; 1.4%; mean age, 69.7±13.6 years; 36.8% women), late-AF (n=161; 2.5%; mean age, 73.8±11.2 years; 41.6% women), and no AF (n=6284; 96.1%; mean age, 63.8±13.6 years; 27.3% women). 

Medical records and electrocardiography results were used to verify the occurrence of AF. Participants were followed from January 2002 to September 2014 (median follow-up, 5 years and 11 months). The study’s primary outcomes were all-cause mortality and initial ischemic stroke.

The rate of death was higher in patients with late- and early-PAF compared with those with no-AF (55.3%, 43.2%, and 29.2%, respectively; P <.001). The rates of stroke were found to be higher in patient with late- vs no-AF (10.6% vs 4.2%, respectively; P <.001), but were comparable for participants with early (5.3%) vs no-AF. In the late-AF group, stroke risk was found to be underestimated by factors including congestive heart failure, hypertension, age ≥75, diabetes mellitus, stroke or transient ischemic attack, vascular disease, age 65-74, and the (CHA₂DS₂-VASc) score for atrial fibrillation in women.

After adjusting for CHA₂DS₂-VASc scores ≥2, the risk for stroke was found to be higher in patients with late- vs non-AF (hazard ratio [HR], 2.44; 95% CI, 1.49-4.00; P <.001). In addition, patients with a CHA₂DS₂-VASc score ≥2 had an increased risk for stroke (cause-specific HR, 4.20; 95% CI, 3.11-5.68; P <.001), and participants with a CHA₂DS₂-VASc score ≥2 and late-AF were 10.2 times more likely to experience an ischemic stroke. A CHA₂DS₂-VASc score ≥2  was independently associated with a risk for death (HR, 6.82; 95% CI, 5.96-7.82; P <.001), but mortality was comparable between the early-PAF and late-AF groups at follow-up (P = .292).

Study limitations include its retrospective design, single center setup, small sample size, and possible misclassification of some patients with no-AF.

“In conclusion, the study generates the hypothesis that patients with early-PAF may not have a high stroke risk, questioning the indication for long-term anticoagulation,” noted the authors.

Reference

Axelrod M, Gilutz H, Plakht Y, Greenberg D, Novack L. Early atrial fibrillation during acute myocardial infarction may not be an indication for long-term anticoagulation. Angiology. February 2020:1-8. doi:10.1177/0003319720908760