Adding Rigor to Stroke Rate Investigations in Patients With Atrial Fibrillation
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Article, see p 208
Effective stroke prevention in patients with atrial fibrillation (AF) means using oral anticoagulation (OAC) therapy, which reduces stroke, systemic embolism, and all-cause mortality. The risk is not homogeneous and depends on associated stroke risk factors, with the more commonly encountered risk factors used to formulate stroke risk stratification schemes such as the CHA2DS2-VASc score.
Clinical risk factor–based risk scores such as CHADS2 or CHA2DS2-VASc have a modest predictive value for identifying the high-risk patients who develop thromboembolism (with c indexes, a measure of predictive value, of ≈0.60), and even the addition of (multiple) biomarkers or imaging might (statistically) improve the c indexes to ≈0.65 to 0.70, at the cost of greatly losing simplicity and practicality and adding expense.
Even a single stroke risk factor confers risk, but randomized, clinical trials of patients with AF with a single stroke risk factor have generally enriched patient populations, often with ≥2 stroke risk factors, to achieve high event rates to minimize patients needed and to ensure a reasonable follow-up period. Some recent randomized, clinical trials (RE-LY [Randomized Evaluation of Long-Term Anticoagulation Therapy], ARISTOTLE [Apixaban for Reduction in Stroke and Other Thrombo-Embolic Events in Atrial Fibrillation], AVERROES [Apixaban Versus Acetylsalicylic Acid (ASA) to Prevent Stroke in Atrial Fibrillation Patients Who Have Failed or Are Unsuitable for Vitamin K Antagonist Treatment], ACTIVE [Atrial Fibrillation Clopidogrel Trial With Irbesartan for Prevention of Vascular Events], and SPORTIF [Stroke Prevention Using an Oral Thrombin Inhibitor in Patients With Atrial Fibrillation]) have enrolled a minority of patients with AF and a single stroke risk factor, but a major source of evidence is large observational studies.
In this issue of Circulation, Quinn and colleagues1 attempted to summarized the available information from observational studies on rates …