Differences between cardiac memory T wave changes after idiopathic left ventricular tachycardia and ischemic T wave inversion induced by acute coronary syndrome

Background Cardiac memory (CM) after idiopathic left ventricular tachycardia (ILVT) mimics ischemic T wave inversion (TWI) induced by acute coronary syndrome (ACS). We aimed to establish electrocardiography criteria for differentiating the CM from ischemic TWI. Methods and results We evaluated 16 ILVT and 48 ACS patients. We identified TWI after ILVT in 9/16 patients (CM group), typically in leads II, III, aVF, aVR, and V_4–6. The characteristics of CM were similar to TWI induced by ACS involving right coronary artery, but the CM group had more TWI in V₄ and shorter QTc. The criteria of (1) positive T in aVL, (2) negative or isoelectric T in II, and (3) negative T in V_4–6 or (4) QTc < 430 ms were 100% sensitive and 96% specific for the CM group. Conclusion CM after ILVT can be differentiated in most cases from ischemic TWI by the distribution of TWI and the QTc.