Monophasic action potential and sinus rhythm stability after conversion of atrial fibrillation.

. Right atrial MAP has been recorded after conversion of atrial fibrillation in 11 patients, 10 of them after DC shock and 1 after a spontaneously reverting attack of atrial fibrillation. The duration of the right atrial MAP has been of prognostic value for the 3-month maintenance of sinus rhythm. Three patients who maintained sinus rhythm more than 3 months had a MAP duration in the same range as is found in patients free from atrial fibrillation. Six patients who relapsed into atrial fibrillation within 3 months had a MAP duration lower than the arrhythmia-free population. In 2 patients MAP could not be recorded during sinus rhythm. The short duration of the right atrial MAP seems to reflect the arrhythmia tendency and can probably be explained by a low atrial muscle potassium content.