This 25-year-old woman with chronic respiratory failure and hypoventilation secondary to kyphoscoliosis and restrictive lung disease is admitted to the Intensive Care Unit with pulmonary aspergillosis:

• Sinus tachycardia 110/min
• Biatrial enlargement
• Right axis deviation
• Right ventricular hypertrophy
• Diffuse T wave abnormality

The presence of tall P waves (>2.5 mm) in the inferior leads and deeply negative P waves in V1 fully justifies the ECG diagnosis of biatrial enlargement. However, the echocardiogram showed no left atrial enlargement, and the P wave abnormality may be actually due to displacement and rotation of the large right atrium. The patient had proven marked pulmonary hypertension and right ventricular hypertrophy.

There is an rSR’ pattern in V1, however the diagnosis of Incomplete right bundle branch block (iRBBB) was not made because of the narrow QRS (the QRS duration was <90 msec)