Occasionally, the electrocardiogram may suggest atrial fibrillation in some leads, and atrial flutter in others. This ECG, from a 72 year old male suggests atrial flutter in lead V1, but is more suggestive of atrial fibrillation in the other leads. It is thought that dissimilar atrial rhythms, with atrial flutter in one atrium (probably the right) and atrial fibrillation in the other may explain this ECG pattern.