The causes and management of atrial fibrillation.

Atrial fibrillation is present in approximately 10% of the population aged over 65 years, in whom its presence is associated with a significantly increased morbidity and mortality. Principal complications include reduced cardiac output and the precipitation of heart failure and thromboembolic phenomena, including strokes and peripheral emboli. In the majority of cases atrial fibrillation is associated with ischaemic heart-disease and hypertension. Other important causes are thyrotoxicosis, valvular heart-disease and atrial septal defect. The primary aims of treatment in atrial fibrillation are to terminate the arrhythmia (cardioversion) with either drugs or direct current (DC) shock and to prevent its recurrence. Effective cardioversion may necessitate the treatment of underlying pathology. If these primary aims cannot be achieved then an attempt must be made to effectively control the ventricular rate with drugs such as digoxin. Recently, further strong evidence has been provided to support the role of anticoagulants and antiplatelet drugs in preventing the major problem of systemic thromboembolic complications. Some of the special difficulties relating to the treatment of atrial fibrillation associated with thyrotoxicosis as well as paroxysmal atrial fibrillation will also be considered.