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Related Experiment Video

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A Magnetic Resonance Imaging Protocol for Stroke Onset Time Estimation in Permanent Cerebral Ischemia

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T-vector direction differentiates postpacing from ischemic T-wave inversion in precordial leads.

Alexei Shvilkin¹, Kalon K L Ho, Michael R Rosen

¹Beth Israel Deaconess Medical Center, Boston, Mass 02215, USA.

|February 16, 2005

Summary

Cardiac memory (CM) causes T-wave inversion mimicking ischemia. New ECG criteria using T-wave patterns can now reliably distinguish CM from ischemic T-wave inversion.

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Area of Science:

Cardiology
Electrocardiography

Background:

Postpacing precordial T-wave inversion (TWI), or cardiac memory (CM), resembles ischemic TWI.
Current ECG criteria cannot reliably differentiate between CM and ischemic TWI.

Purpose of the Study:

To determine if CM induced by right ventricular pacing exhibits a distinct TWI pattern compared to ischemic TWI.
To develop ECG criteria for differentiating CM from ischemic TWI.

Main Methods:

Compared T-wave axis, polarity, and amplitude on 12-lead ECGs during sinus rhythm between CM and ischemic groups.
Analyzed 13 patients with CM (DDD pacing, short AV delay) and 47 ischemic patients with precordial TWI.

Main Results:

A specific combination of ECG findings showed high diagnostic accuracy.
The criteria included positive T(aVL), positive or isoelectric T(I), and maximal precordial TWI > TWI(III).
This combination was 92% sensitive and 100% specific for CM.

Conclusions:

Right ventricular pacing-induced CM creates a unique T-vector pattern.
This pattern allows for effective discrimination from ischemic TWI, irrespective of coronary artery involvement.