Follow-up of atrial fibrillation: The initial experience of the Canadian Registry of Atrial Fibrillation

Abstract

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-up 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 atrial fibrillation at seven Canadian centres. At baseline, a comprehensive database recorded clinical, laboratory, and echocardiographic variables. No specific intervention was initiated and care was left to the attending physicians. Follow-up was performed at 3 months, 1 year, then annually. Echocardiograms were repeated every 2 years. Recurrence of atrial fibrillation, medical intervention, stroke, death, and other significant 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 studies have been undertaken on these patients. One study compared the variables of patients who were symptomatic with those who were asymptomatic. This study demonstrated that symptoms were more likely to occur if the patient were younger, had high blood pressure and high ventricular response during atrial fibrillation, and were female. These all achieve statistical significance and a formula was developed to predict the probability of symptoms in different subgroups of patients. Antiarrhythmic drug use was evaluated. Sotalol and propafenone were the most commonly used drugs and their use increased when atrial fibrillation was recurrent. Many patients initially received no antiarrhythmic drugs. Trends suggest that therapy is more aggressive with recurrence of the arrhythmia. The prevalence of thyroid abnormalities was investigated utilizing sensitive TSH measurements. This showed that overt hyperthyroidism is rare (1%) but laboratory abnormalities and history of thyroid dysfunction occurred more frequently, in 19% of patients. Another study evaluated antithrombotic therapy. Factors known to increase stroke risk, including congestive heart failure, previous stroke, and large left atrium all increased the use of anticoagulants. Anticoagulants were used more frequently in patients over the age of 65 and in patients with recurrent or chronic atrial fibrillation. There was concern that 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 with the ultimate goal to utilize baseline data to predict clinical outcomes.

Estudo transversal das estratégias de tratamento clínico na fibrilação atrial

“…The higher prevalence of patients with ventricular dysfunction (EF < 40%) in rate control strategy (95%) was a finding similar to that of RecordAF 15 (59.5%). The difference in the magnitude of the findings might be attributed to the smaller sample assessed in the present study.…”

Limitations to antiarrhythmic drug use in patients with atrial fibrillation

“…Detailed methods of the registry have been reported elsewhere. [12][13][14] Briefly, the registry began to enroll patients in 1991 in 6 cities across Canada; enrollment was 404 (56%) had structural heart disease, which included 227 (31%) with ischemic heart disease, 158 (22%) with left ventricular systolic dysfunction and 106 (15%) with heart failure. Interpretation: The high burden of comorbid disease and concomitant drug use in a large proportion of patients with AF limits the suitability of existing antiarrhythmic drugs.…”

Atrial fibrillation: review of current treatment strategies

“…Generally, palpitations are more common in paroxysmal AF, and shortness of breath in more chronic AF. AF can also have other non-specific symptoms such as fatigue (30). However, not all types of AF are symptomatic, with paroxysmal AF patients more frequently being asymptomatic (31).…”