[Atrial fibrillation--epidemiological and electrophysiological aspects].

Atrial fibrillation is a common and therapy-requiring cardiac arrhythmia. The chronic form becomes identified in population studies from the age of 50 and increases with age. The number of Norwegian individuals with this arrhythmia is estimated to be slightly in excess of 40,000 and it will increase approximately by another 5,000 until the year 2010. Mechanisms responsible for initiation and maintenance of the arrhythmia are increasingly better understood. The paroxysmal form often has a focal origin, allowing curative treatment, but can also be associated with signs of deficient interatrial conduction. The chronic form is perpetuated partly by a shortening of atrial myocardial refractoriness, attributed to a failure in the intracellular turnover of Ca-ions due to the high excitation rate. Ongoing studies are expected to illustrate the clinical benefit of Ca-blockers prior to cardioversion of chronic atrial fibrillation. The further relapse rate is low in patients who have maintained sinus rhythm more than 1-2 months following conversion. It is therefore possible that, following a successful conversion to sinus rhythm, aggressive antiarrhythmic treatment should be given during a limited period only--a strategy which has to be evaluated in prospective studies.