Note that left atrial enlargement is not able to be diagnosed in the presence of atrial fibrillation because this rhythm is defined by erratic atrial activity and no visible P wave on the ECG.

Left atrial enlargement can be diagnosed on the ECG or via echocardiography. When left atrial enlargement occurs, it takes longer for cardiac action potentials to travel through the atrial ...

Left atrial enlargement (LAE ... If the VSD is large, an X-ray can also show enlargement of the heart. However, ECG and chest X-ray results are typically normal if the hole is small.

AV, atrioventricular; bpm, beats per minute; LVH, left ventricular hypertrophy ... of the second heart sound because IRBBB can be an associated ECG finding in patients with an atrial septal defect.