ECG Criteria for Right Atrial Enlargement

In 1978, an ECG task force reported that the detection of right atrial enlargement should be based on the presence of an increase in P wave amplitude in the limb leads, in association with a peaked P wave morphology, and rightward frontal plane P wave axis.¹This pattern is known asP pulmonale(Fig 1, upper trace). This suggestion has some support in two autopsy studies. Berliner and Master,²in 1938, reported that subjects with isolated left atrial hypertrophy had normal P wave amplitude, while those with biatrial hypertrophy had an increase in P wave amplitude, although in four cases of isolated right atrial hypertrophy, no P wave abnormalities were noted. In 1962, Caird and Wilken³found right atrial abnormalities in patients with obstructive lung disease. The P pulmonale ECG pattern was noted in seven of the 11 patients with a dilated right atrium, three patients with