Definitions & Background

Classic definition of the term cardiac memory (CM) refers to the persistent T-wave changes on the ECG after a period of wide QRS rhythms that become evident once normal ventricular activation pattern is restored.

After normal ventricular activation is restored, the T wave “remembers” and mirrors the direction of the wide QRS complexes. Therefore, cardiac memory results in positive T waves in leads that had positive wide QRS complexes and negative T waves in leads that had negative wide QRS complexes.

Essentially, this means that after wide complex rhythms (VT, PVCs), ventricular pacing, QRS widening with sodium channel blocker toxicity, ventricular pre-excitation etc… transient TW changes can develop.

This is secondary to adaptation of myocardial repolarization to the new and abnormal activation sequence. Process is then medicated due to ventricular contraction pattern and local ventricular wall stress as opposed to electrical changes alone.

References

  1. Cardiac Memory | Circulation: Arrhythmia and Electrophysiology (ahajournals.org)
  2. Cardiac memory: an under-recognised cause of deep T wave inversion in a patient presenting with chest pain | BMJ Case Reports
  3. Cardiac Memory-induced T-wave Inversions - The Western Journal of Emergency Medicine (westjem.com)
  4. Post-pacemaker T-wave Inversions: Cardiac Memory - ScienceDirect (mcmaster.ca)