Stroke prophylaxis in atrial fibrillation: who gets it and who does not?

Aims Underuse of warfarin for stroke prophylaxis in atrial fibrillation (AF) is extensive and represents a major problem in clinical practice. To identify factors associated with warfarin treatment in eligible AF patients. Methods and results The study population consisted of all Swedish resident AF patients at the Stockholm South General Hospital during 2002 (n=2796). Medical records were examined and complemented by data from the Swedish National Hospital Discharge Register. Sixty-eight percent of the patients (1898/2796) had indications, and no apparent contraindications for warfarin treatment. Of these 54% (1029/1898) got warfarin. Factors favouring warfarin treatment after adjustment for other factors were history of ischaemic stroke, an implanted pacemaker, treatment in a cardiology rather than internal medicine ward and valvular defect. Factors associated with a reduced likelihood of warfarin treatment were paroxysmal type of AF and age > 80 years. Important risk factors for stroke in AF like heart failure, hypertension, and diabetes did not increase the chances of warfarin treatment. Conclusion Risk stratification using known risk factors of stroke seems to affect warfarin treatment only to a minor degree in clinical practice. Undertreatment was particularly common in patients with paroxysmal AF and in patients aged > 80 years and calls for improved clinical routines in accordance with international guidelines.