AF doubles postoperative stroke risk
MedWire News: Research shows that patients undergoing surgery have a doubled risk for postoperative stroke if they have atrial fibrillation (AF).
AF is a major risk factor for stroke in the general population, but its influence in patients undergoing operations is unclear.
“Knowing the risk for stroke in these patients is clinically relevant because if it the risk is very high, it may justify administering peri-operative ‘bridging’ anticoagulant therapy, typically using therapeutic doses of low-molecular-weight heparin before and after surgery during the time when warfarin treatment is withheld,” say Scott Kaatz (Henry Ford Hospital, Detroit, Michigan, USA) and co-workers.
The team addressed this using data on 69,202 patients with and 2,470,649 without chronic AF who underwent a surgical or invasive procedure between 1996 and 2005. These patients underwent procedures such as cardiac, orthopedic, vascular, abdominal, and neurologic surgery. Kaatz et al excluded patients who underwent carotid surgery, due to the attendant stroke risk.
Between 0 and 30 days after the procedure, 1.8% of AF patients suffered stroke, compared with 0.6% of those without. The equated to a 2.1-fold increased risk after accounting for age, race, gender, and the components of the CHADS2 score (congestive heart failure, hypertension, age of at least 75 years, diabetes, and previous stroke).
The stroke risk increase associated with AF was largest among patients undergoing neurologic surgery (2.9-fold) and vascular surgery (2.4 fold) and was lowest among those undergoing coronary artery bypass surgery (1.4 fold) and valve surgery (1.3 fold). There was no excess risk among AF patients undergoing lung surgery.
Besides AF, the CHADS2 components also predicted stroke, with risk increases ranging from 1.5 to 2.3 fold. “However, the value of the CHADS2 index score in stratifying the risk for postoperative stroke was not specifically assessed,” caution the researchers.
“The findings of this study are clinically important because most postoperative strokes are embolic and 70% of such strokes are associated with permanent neurologic deficit or death,” say Kaatz and team in the Journal of Thrombosis and Haemostasis.
“The higher observed risk for postoperative stroke in patients with chronic AF after surgery suggests an urgent need to investigate interventions to minimize the risk for postoperative stroke in such patients.”
They conclude: “Whether the risks and costs of bridging therapy in these populations justifies the putative reduction in stroke provided by bridging anticoagulation therapy can only be definitively answered in a randomized trial.”
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By Eleanor McDermid