The impact of comorbidities on stroke prophylaxis strategies in atrial fibrillation patients.

Arial fibrillation (AF) is the most commonly occurring sustained arrhythmia in the United States and is associated with increased mortality. AF is a risk factor for ischemic stroke, and risk factors for AF include comorbid conditions such as congestive heart failure, diabetes mellitus, older age, hypertension, diabetes, pulmonary disease, and history of stroke, transient ischemic attack, or heart failure. Risk stratification for ischemic stroke in AF patients is based on scoring a group of risk factors that allows for the appropriate tailoring of antithrombotic therapy. The vitamin K antagonists are effective at reducing ischemic stroke rates in medium-risk to high-risk patients and are therefore generally recommended for this group. However, a large proportion of these patients are not treated with vitamin K antagonists because of the potential for adverse outcomes, particularly in elderly patients. New direct thrombin inhibitors and direct Factor Xa inhibitors in development offer the possibility of simplifying treatment and management although offering similar or better efficacy and safety profiles to warfarin. In light of these potential new treatments, the importance and improvement of risk stratification methods and the resulting recommendations in thromboprophylaxis become even more paramount as they make it more likely that medium-risk to high-risk patients can be treated safely.