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Transient U wave inversion during variant angina
Insights
Transient U wave inversion is common during variant angina with anterolateral ischemia but not inferoposterior ischemia. This ECG finding is linked to myocardial ischemia, not blood pressure changes.
Area of Science:
- Cardiology
- Electrophysiology
Background:
- Variant angina is characterized by coronary artery spasms causing myocardial ischemia.
- Electrocardiogram (ECG) changes, including ST-segment elevation, are typical during anginal attacks.
- The significance of transient U wave inversion during variant angina requires further investigation.
Purpose of the Study:
- To investigate the prevalence and clinical significance of transient U wave inversion in patients with variant angina.
- To determine the association between U wave inversion and the location of myocardial ischemia during variant angina.
- To differentiate the cause of U wave inversion, distinguishing between myocardial ischemia and changes in blood pressure.
Main Methods:
- Studied 43 patients diagnosed with variant angina.
- Categorized patients into two groups based on ECG findings during angina: anterolateral ST elevation (Group A) and inferoposterior ST elevation (Group B).
- Assessed U wave inversion during spontaneous angina and performed treadmill exercise testing in a subset of patients to evaluate the role of blood pressure.
Main Results:
- Transient U wave inversion occurred in 66.7% of Group A patients (anterolateral ischemia) but in none of Group B patients (inferoposterior ischemia) during anginal attacks.
- U wave inversion was not present on resting ECGs in the absence of angina.
- Treadmill exercise testing in 12 patients did not induce angina or U wave inversion despite elevated systolic blood pressure, suggesting ischemia, not hypertension, as the cause.
Conclusions:
- Transient U wave inversion is a frequent finding associated with anterolateral myocardial ischemia in variant angina.
- U wave inversion in variant angina is likely caused by myocardial ischemia rather than a transient rise in systolic blood pressure.
- The presence and characteristics of U wave inversion may help localize the ischemic region in variant angina.
Abstract:
We studied the prevalence and clinical significance of transient U wave inversion in 43 patients with variant angina. Twenty-four patients (group A) had ST segment elevation in the anterolateral and 19 patients (group B) had this finding in the inferoposterior leads of the ECG during spontaneous angina. In none of these patients was U wave inversion present on the resting 12-lead ECG in the absence of anginal attack. During anginal attacks, U wave inversion developed in association with ST segment elevation in 16 patients (66.7%) of group A but in no patient of group B. To exclude the possibility that a transient rise of systolic blood pressure during angina caused U wave inversion, treadmill exercise testing was done in the 16 patients after the discontinuation of antianginal drugs. In 12 of the 16 patients, exercise testing did not produce angina or U wave inversion despite a marked elevation of systolic blood pressure. These results indicate that transient U wave inversion frequently develops with anterolateral ischemia but not with inferoposterior ischemia during attacks of variant angina. It is likely that transient U wave inversion was caused by myocardial ischemia but not by a rise of blood pressure during angina.