Tessa Davis. Pulmonary embolism, Don't Forget the Bubbles, 2014. Available at:
Most patients with an acute pulmonary embolus will have no other ECG abnormality other than a sinus tachycardia. PE causes problems for the right ventricle therefore look for an isolated RAD or possibly new T wave inversion in R chest leads (V1, V2), RBBB or supraventricular arrhythmias.
The combination of RAD (prominent S in lead 1) with a Q wave and an inverted T wave in lead 3 (“S1Q3T3” in the limb leads) is said to be characteristic of pulmonary embolism but is by no means diagnostic.