Transient terminal U wave inversion as a more specific marker for myocardial ischemia

Area of Science:

• Cardiology
• Electrophysiology
• Diagnostic ECG

Background:

• Transient U wave inversion on electrocardiograms (ECGs) is associated with both myocardial ischemia and elevated systemic blood pressure.
• Distinguishing the cause of U wave inversion is crucial for accurate patient management.

Purpose of the Study:

• To compare the characteristics of U wave inversion in patients with variant angina versus those with hypertension.
• To determine if the ECG phase of U wave inversion can differentiate between ischemic and non-ischemic causes.

Main Methods:

• ECG analysis of U wave inversion during chest pain attacks in 21 patients with variant angina and 38 patients with hypertension.
• Evaluation of U wave inversion during a cold pressor test in variant angina patients on calcium entry blockers.
• Defined significant U wave inversion as a discrete negative deflection >0.05 mV within the TP segment.

Main Results:

• U wave inversion preceding positive U wave deflection (initial U wave inversion) was observed in hypertensive patients.
• U wave inversion occurring after positive U wave deflection (terminal U wave inversion) was seen in variant angina patients during attacks.
• Transient initial U wave inversion occurred in 43% of variant angina patients during a cold pressor test, despite no anginal attacks.

Conclusions:

• U wave inversion can be classified as initial or terminal based on its phasic relationship to positive U wave deflection.
• Terminal U wave inversion is associated with regional myocardial ischemia.
• Initial U wave inversion appears related to elevated blood pressure rather than myocardial ischemia.