Multifocal Versus Ectopic Atrial Tachycardia!

The above electrocardiogram (EKG) was recorded in a young patient with abdominal pain and palpitations. At first glance the P wave morphology appears to vary, with greater than 3 different morphologies identified as indicated by the different color arrows, suggestive of multifocal atrial tachycardia at 102 beats/minute (BPM). A closer look, however, reveals an initial sinus rhythm (first 2 beats, light green arrows) followed by what seems to be gradual fusion of sinus P waves with ectopic atrial P waves (dark green and light brown arrows), likely a “warm-up period”, with subsequent complete usurpation of the sinus rhythm by an ectopic atrial tachycardia (red arrows).