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Perioperative Atrial Fibrillation and the Long-Term Risk of Ischemic Stroke
Study Questions:
What is the association between perioperative atrial fibrillation and the long-term risk of stroke?
Methods:
This was a retrospective cohort study using administrative claims data on patients hospitalized for surgery (as defined by surgical diagnosis-related group codes), and discharged alive and free of documented cerebrovascular disease or pre-existing atrial fibrillation from nonfederal California acute care hospitals between 2007 and 2011. Patients undergoing cardiac versus other types of surgery were analyzed separately. Previously validated diagnosis codes were used to identify ischemic strokes after discharge from the index hospitalization for surgery. The primary predictor variable was atrial fibrillation newly diagnosed during the index hospitalization, as defined by previously validated present-on-admission codes. Patients were censored at postdischarge emergency department encounters or hospitalizations with a recorded diagnosis of atrial fibrillation.
Results:
Of 1,729,360 eligible patients, 24,711 (1.43%; 95% confidence interval [CI], 1.41%-1.45%) had new-onset perioperative atrial fibrillation during the index hospitalization and 13,952 (0.81%; 95% CI, 0.79%-0.82%) experienced a stroke after discharge. In a Cox proportional hazards analysis accounting for potential confounders, perioperative atrial fibrillation was associated with subsequent stroke both after noncardiac and cardiac surgery. The association with stroke was significantly stronger for perioperative atrial fibrillation after noncardiac versus cardiac surgery (p < 0.001 for interaction). For noncardiac surgery, the cumulative rate of stroke 1 year after hospitalization was 1.47% in patients with perioperative atrial fibrillation and 0.36% when no perioperative atrial fibrillation was present (hazard ratio, 2.0; 95% CI, 1.7-2.3). For patients undergoing cardiac surgery, the cumulative risk of stroke 1 year after hospitalization was 0.99% with perioperative atrial fibrillation present, and 0.83% when no perioperative atrial fibrillation was present (hazard ratio, 1.3; 95% CI, 1.1-1.6).
Conclusions:
Among patients hospitalized for surgery, perioperative atrial fibrillation was associated with an increased long-term risk of ischemic stroke, especially following noncardiac surgery.
Perspective:
Atrial fibrillation, when first diagnosed in the perioperative period, especially after noncardiac surgery, suggests patients’ vulnerability to atrial fibrillation. Such patients warrant closer follow-up. It is possible that monitoring these patients with event monitors capable of detection of asymptomatic atrial fibrillation might result in the demonstration of the arrhythmia’s recurrence and inform long-term anticoagulation management.
Keywords: Stroke, California, Diagnosis-Related Groups, Perioperative Period, Emergency Service, Hospital, Cardiac Surgical Procedures, Hospitalization
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