Study objectives: We sought to assess the incidence of transient U-wave inversion during vasospasm of the left anterior descending coronary artery (LAD) with ST-segment depression as opposed to that with ST-segment elevation.
Design: Retrospective study.
Setting: Cardiology division of acute-care hospitals.
Patients: We studied 49 patients with vasospastic angina whose vasospasm was induced in the LAD, not in the left circumflex coronary artery, by intracoronary injection of acetylcholine.
Measurements and results: The ECG traces obtained during acetylcholine-induced vasospasm of the LAD were examined. Based on the direction of ST-segment shift, the patients were categorized into two groups: the ST-segment elevation group (n = 27) and the depression group (n = 22). There were no differences in age, gender, or cardiovascular risk factors between the two groups. The distribution of the spastic site in the LAD was also similar. A total reduction in luminal diameter during a provoked attack was more often observed in the ST-segment elevation group than in the ST-segment depression group (37% vs 9%, p = 0.02). Collateral circulation to the LAD was found in only one patient in each group. There were no differences between the two groups in heart rate, systolic BP, and double product of heart rate and systolic BP during the attack. The incidence of acetylcholine-induced anginal attack with U-wave inversion in the ST-segment depression group was nearly as high as that in the ST-segment elevation group (77% vs 78%, p > 0.99).
Conclusions: The development of transient U-wave inversion during vasospasm of the LAD induced by intracoronary injection of acetylcholine does not depend on the magnitude of myocardial ischemia as judged by the direction of ST-segment shift.