Pulmonary Embolism

The classical ECG signs of acute pulmonary embolism are S_IQ_IIIT_III, which are mnemonics representing deep S wave in lead I, pathological Q wave in lead III, and inverted T wave in lead III:

Other nonspecific signs include (see ECG above):

	Sinus tachycardia and atrial and ventricular ectopic beats.
	Right axis deviation.
	Right ventricular strain pattern with inverted T waves in right chest leads.
	Incomplete or complete right bundle branch block pattern.
	Slow R wave progression in chest leads

But all these ECG signs may not be present even in frank pulmonary embolism.