Duration of diabetes may be a more important predictor of ischemic stroke than glycemic control for patients with diabetes and atrial fibrillation (AF), according to recent research published in the Journal of the American College of Cardiology.

While previous studies have established an association between elevated hemoglobin A1c (HbA1c) and duration of diabetes with risk of ischemic stroke, it is still unknown whether there is an association among patients with diabetes with AF because the pathophysiology of stroke may be different in these patients. Therefore, researchers sought to assess this association in patients with AF who were offanticoagulation therapy in clinical care.

Researchers found that “the increased rate of ischemic stroke in those who have had diabetes for an estimated ≥3 years appeared to be independent of age as the association was present in both older (≥75 years) and younger (<75 years) subjects.” 


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The study included a population cohort from the ATRIA (Anticoagulation and Risk Factors in Atrial Fibrillation) study. Researchers included 2101 patients with diabetes in the duration analysis. At the start of the study, 39.8%  of the patients had diabetes for <3 years and 60.2% had diabetes for ≥3 years. Of the 1933 diabetic patients included in the HbA1c analysis, 45.7% had HbA1c that was <7.0%, 35.7% had between 7.0% and 8.9%, and 18.6% had ≥9.0% at baseline.

Rate of ischemic stroke was estimated according to the varying measures of diabetes duration. They compared individuals who lived with diabetes ≥3 years with patients who had diabetes <3 years, and compared the different HbA1c values with attention to the periods when patients were not taking anticoagulants. 

The data showed that patients who had diabetes ≥3 years had an increased rate of ischemic stroke when compared with patients with diabetes <3 years (adjusted hazard ratio [HR]: 2.04, 95% confidence interval [CI]: 1.27-3.26). The increased rate of ischemic stroke associated with diabetes duration remained elevated, even after adjustment for stroke risk factors in multivariable analyses (adjusted HR: 1.74; 95% CI: 1.10-2.76).

When researchers compared levels of glycemic control in multivariable models adjusting for stroke risk factors, insulin use, and diabetes duration, they found that neither poor glycemic control (HbA1c  ≥9.0%, adjusted HR: 1.04; 95% CI: 0.57-1.92) nor moderately increased HbA1c (7.0-8.9%; adjusted HR: 1.21; 95% CI: 0.77-1.91) were associated with increased stroke when compared to individuals with HbA1c <7.0%. 

Duration of diabetes may be most important among patients with AF because they have enhanced thrombin generation, impaired fibrinolysis with prolonged lysis time, and unfavorably altered plasma fibrin clot structure, which could increase the risk of thrombotic events.

“Given the relatively small association between the diagnosis of diabetes and ischemic stroke in several published studies, accounting for duration of diabetes may improve stroke risk models for patients with AF,” researchers concluded. 

Reference

Ashburner JM, Go AS, Chang Y, et al. Effect of diabetes and glycemic control on ischemic stroke risk in AF patients. J Am Coll Cardiol. 2016; 67(3):735-1097.