FOLLOW-UP OF ATRIAL-FIBRILLATION - THE INITIAL EXPERIENCE OF THE CANADIAN REGISTRY OF ATRIAL-FIBRILLATION

Previous reports of the follow-up of patients with atrial fibrillation have been confusing because of the variety of clinical presentations, heterogeneity of underlying pathology, and the initiation of follow-u p at various stages of the patient's disease. The Canadian Registry of Atrial Fibrillation (CARAF) is a non-interventional, follow-up study of patients enrolled at the time of their initial diagnosis with atria l fibrillation at seven Canadian centres. At baseline, a comprehensive database recorded clinical, laboratory: and echocardiographic variabl es. No specific intervention was initiated and care was left to the at tending physicians. Follow-up was performed at 3 months, 1 year, then annually. Echocardiograms were repeated every 2 years. Recurrence of a trial fibrillation, medical intervention, stroke, death, and other sig nificant events have been specifically recorded. To date, 967 patients have been enrolled. Seven hundred and sixty-seven patients have been followed for 1 year, 468 for 2 years, and 217 for 3 years. Several stu dies have been undertaken on these patients. One study compared the va riables of patients who were symptomatic with those who were asymptoma tic. This study demonstrated that symptoms were more likely to occur i f the patient were younger, had high blood pressure and high ventricul ar response during atrial fibrillation, and were female. These all ach ieve statistical significance and a formula was developed to predict t he probability of symptoms in different subgroups of patients. Antiarr hythmic drug use was evaluated. Sotalol and propafenone were the most commonly used drugs and their use increased when atrial fibrillation w as recurrent. Many patients initially received no antiarrhythmic drugs . Trends suggest that therapy is more aggressive with recurrence of th e arrhythmia. The prevalence of thyroid abnormalities was investigated utilizing sensitive TSH measurements. This showed that overt hyperthy roidism is rare (1%) but laboratory abnormalities and history of thyro id dysfunction occurred more frequently, in 19% of patients. Another s tudy evaluated antithrombotic therapy. Factors known to increase strok e risk, including congestive heart failure, previous stroke, and large left atrium all increased the use of anticoagulants. Anticoagulants w ere used more frequently in patients over the age of 65 and in patient s with recurrent or chronic atrial fibrillation. There was concern tha t hypertension, shown to be a high predictor of stroke, did not result in a significant use of warfarin. Aspirin use was common in patients not placed on anticoagulants. Further studies are being undertaken wit h the ultimate goal to utilize baseline data to predict clinical outco mes.