A giant inverted T wave is > 5 mm deep and symmetrical.
Causes of giant inverted T waves:
(1) apical hypertrophic cardiomyopathy (Yamaguchi syndrome)
(2) elevated intracranial pressure or intracranial hemorrhage
(3) myocardial ischemia (cocaine-induced, etc)
(4) bundle branch block
(5) Wolff-Parkinson-White (WPW) syndrome
(6) idiopathic global T-wave inversion syndrome
(7) post-tachycardia (associated with supraventricular or ventricular tachycardia)
(8) post-pacemaker
(9) following truncal vagotomy
(10) following bilateral carotid endarterectomy
(11) large pulmonary embolus
