Overview

• Enlargement of both the right and left atria

ECG Features

• Criteria met for both left and right atrial enlargement

Right atrial enlargement

• II, III, or aVF: P wave amplitude >2.5 mm (P-pulmonale)
• V1 or V2: P wave amplitude >1.5 mm; if biphasic, initial P wave amplitude >1.5 mm
• Associated conditions: chronic obstructive pulmonary disease, congenital heart disease (e.g. Tetralogy of Fallot, pulmonic stenosis, tricuspid atresia, Eisenmenger’s physiology), pulmonary embolism, normal variant (e.g. small body habitus, vertical heart), secondary to left atrial enlargement (30%; look for left atrial enlargement)

Left atrial enlargement

• II, III, or aVF: notched P wave with 40 ms between each peak and total P wave duration >120 ms (P-mitrale)
• V1: terminal portion of biphasic P wave >1 mm deep and 40 ms wide (e.g. 1 mm wide and 1 mm deep on standard 25 mm/s tracing)
• Associated conditions: left atrial dilation/hypertrophy, intra-atrial conduction delay