Clinical significance of a new diagnosis of atrial fibrillation in patients with vascular disease.

Background: The Cardiovascular Outcomes for People Using Anticoagulation Strategies (COMPASS) trial enrolled patients with vascular disease but excluded patients requiring oral anticoagulation.

Objective: We aimed to explore the clinical significance of a new diagnosis of atrial fibrillation (AF) during follow-up.

Methods: New AF was identified from hospitalization, study drug discontinuation, and adverse event reports. Multivariable Cox regression was used to determine risk factors for new AF. Time-updated covariate analysis was used to study the association of new AF with outcomes.

Results: During a mean follow-up of 23 months, 655 of 27,395 participants (2.4%) were diagnosed with AF (incidence, 1.3 per 100 patient-years). In adjusted analyses, advanced age, male sex, White ethnicity, higher body mass index, higher systolic blood pressure, heart failure, and prior myocardial infarction were associated with new AF. Compared with participants without a new diagnosis of AF during follow-up or before receiving a diagnosis of new AF, participants were at increased risk of a composite outcome of cardiovascular death, stroke, or myocardial infarction after a new diagnosis of AF (8.8 vs 2.4 per 100 patient-years; hazard ratio [HR], 3.66; 95% confidence interval [CI], 2.81-4.75). Risk increases with new AF were also observed for hospitalization for heart failure (6.8 vs 0.8 per 100 patient-years; HR, 8.64; 95% CI, 6.31-11.83) and major bleeding (3.9 vs 1.3 per 100 patient-years; HR, 3.18; 95% CI, 2.15-4.69).

Conclusion: In patients with vascular disease, a new diagnosis of AF was associated with a marked increase in risk of adverse outcomes, especially hospitalization for heart failure.