Background: The clinical role of collateral vessels, which are transiently augmented during coronary artery spasm, remains controversial.
Objective: To examine the correlation between coronary arteriographic and electrocardiographic features during spasm in the left anterior descending artery (LAD).
Methods: We studied 45 patients in whom LAD spasms were induced by administration of acetylcholine or ergonovine maleate into the left coronary artery, or in whom spontaneous LAD spasms were documented during diagnostic cardiac catheterization.
Results: During spasm, only three patients had transient appearance or augmentation of collateral flow opacifying the LAD. In these three patients, electrocardiograms obtained from anterior precordial chest leads during LAD spasm showed ST-segment depression, ST-segment elevation followed by ST-segment depression, and only T-wave change, respectively. Except for these three patients, ST-segment elevations were observed in all other patients (31 of 34) with main-branch spasm of the LAD. However, ST-segment elevation was observed in only two of 11 patients in whom spasm of the diagonal branch alone was induced.
Conclusions: Our observations suggest that the electrocardiographic changes during spasm are not always a sensitive indicator of LAD side branch spasm or LAD main-branch spasm associated with collateral circulation. From consideration of the angiographic features of the collaterals in the three patients with LAD main-branch spasm, we speculate that the balance of tonus of both the recipient and donor arteries, and the degree of organic stenosis of the recipient artery, may have important roles in the mechanism responsible for the change in the appearance of collaterals in patients with coronary spasm.