A patient's ECG recording shows a consistent pattern of two P waves followed by a normal QRS complex and T wave. What is the cause for this abnormal wave pattern?

Left Atrial Enlargement

The ECG has three parts : the P wave, QRS complex and T wave. The P wave is associated with atrial activation (depolarization), QRS complex is related to ventricular activation (depolarization), and T wave is associated with ventricular recovery (repolarization) phase.

In case of Left atrial enlargement, the P wave shows notched pattern. It looks like two P wave (see the following diagram).

The following diagram shows left atrial enlargement and the pattern of ECG associated with it.

So, I think two P waves with normal QRS complex and T wave is caused by Left atrial enlargement.