Key result
U wave inversion in V5 yields ~71% sensitivity for variant angina attacks, outperforming ST elevation.
Why the study?
The diagnostic value of U wave inversion during variant angina attacks, especially in relation to ST segment elevation and coronary artery spasm location, was unclear.
Does U wave inversion provide diagnostic value during attacks of variant angina in patients undergoing ergonovine provocation?
Observational (n=38)
Does U wave inversion provide diagnostic value during attacks of variant angina in patients undergoing ergonovine provocation?
Inverted U waves without ST segment elevation frequently appear during variant angina attacks or recovery, aiding in diagnosis when only lead V5 is monitored.
May aid ECG localization of spasm in variant angina; hypothesis-generating from Level 5 data and requires prospective validation.
Sequential 12 lead electrocardiograms were recorded during angina pectoris induced by ergonovine maleate in 38 patients with variant angina. Transient U wave inversion was observed in 17 patients with ST segment elevation in anterior chest leads, but in only three of 21 patients with ST segment elevation in the inferior leads associated with right coronary artery spasm. In the 17, all of whom had spasm of the left anterior descending coronary artery, the sensitivity of ST segment elevation in V5 was only 41%, and that of U wave inversion 71%. U wave inversion without ST segment elevation occurred during attacks in 35% of patients. During the recovery phase, the sensitivity of U wave inversion was 82% in V4 and 65% in V5, though ST segment elevation was absent in both V4 and V5. Thus, inverted U waves without ST segment elevation often appear in marginal ischaemic zones or during the time of recovery from temporary ischaemia. Detection of inverted U waves should aid in the diagnosis of variant angina when only lead V5 is used as a monitor and when electrocardiograms are recorded only during the recovery phase.
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Miwa et al. (1983) conducted an observational in Variant angina (n=38). Ergonovine maleate induced angina pectoris was evaluated on Sensitivity of U wave inversion and ST segment elevation. U wave inversion during attacks of variant angina demonstrated a sensitivity of 71% in lead V5, compared to 41% for ST segment elevation, highlighting its diagnostic value.
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