@NathanG - I agree that catheters are more precise; however it’s not true that the P waves are inconclusive. The article plainly states that they could indicate a right or left enlargement.
At least it will give you some idea of where to look. At any rate, these interpretations are best left up to the doctor not to the patient.
I am rarely given the readout of what my heart exam looks like, except if there is something wrong, in which case the doctor will explain what the results mean.