Study Links New-Onset Atrial Fibrillation After Coronary Surgery to Increased Stroke Risk

The researchers revealed that in individuals with postoperative AF following CABG, factors such as a history of ischemic stroke, older age, heart failure, and previous myocardial infarction were linked to an increased risk of ischemic stroke within one year. The findings suggest that clinicians should closely monitor these high-risk groups following surgery.

New-onset postoperative atrial fibrillation (POAF) following coronary artery bypass grafting raises the risk of ischemic stroke, but the factors influencing this risk remain poorly understood. To fill this knowledge gap, Amar Taha, Department of Molecular and Clinical Medicine, Sahlgrenska Academy, Goteborg, Sweden, and colleagues aimed to identify the main factors associated with one-year ischemic stroke risk, compare the predictive capabilities of the CHA2DS2-VASc and ATRIA scores for ischemic stroke, and evaluate the dispensing of oral anticoagulation (OAC) at discharge.

For this purpose, the researchers conducted a nationwide cohort study utilizing prospectively collected data from four mandatory Swedish national registries. They included all first-time isolated CABG patients who developed POAF between 2007 and 2020. Multivariable logistic models were employed to identify predictors of ischemic stroke, while C-statistics assessed the predictive abilities of the CHA2DS2-VASc and ATRIA scores in patients not receiving OAC. Additionally, the study described OAC dispensing patterns concerning stroke-associated factors.

Based on the study, the researchers reported the following findings:

• A total of 10,435 patients with postoperative atrial fibrillation were identified. Among those not receiving oral anticoagulation (OAC) (n=6,903), 3.1% experienced an ischemic stroke within one year.
• Key independent predictors of ischemic stroke included advancing age (adjusted odds ratio (aOR) 1.86 per 10-year increase), prior ischemic stroke (aOR 18.56 at 60 years, aOR 5.95 at 80 years), myocardial infarction (aOR 1.55), and heart failure (aOR 1.53).
• The area under the receiver-operating characteristic curve was 0.72 for the CHA2DS2-VASc score and 0.74 for the ATRIA score.
• 71.0% of patients with a stroke risk greater than 2% per year, as indicated by the CHA2DS2-VASc score, were not discharged on OAC.

This large study of patients with postoperative atrial fibrillation after CABG found that having a previous ischemic stroke, being older, having a heart attack, and having heart failure were significant risk factors for ischemic stroke in the first year after surgery. The CHA2DS2-VASc and ATRIA scoring systems were moderately effective at predicting stroke risk within a year for these patients, similar to those with atrial fibrillation who hadn’t had surgery.

The researchers note that while one-third of patients with POAF were discharged on oral anticoagulation, the factors linked to higher stroke risk did not strongly influence the decision to prescribe OAC for these patients.

Reference:

Taha A, Martinsson A, Nielsen SJ, et al. New-onset atrial fibrillation after coronary surgery and stroke risk: a nationwide cohort studyHeart Published Online First: 04 October 2024. doi: 10.1136/heartjnl-2024-324573