Significance of "reciprocal" ST segment depression: left ventriculographic observations during left anterior descending coronary angioplasty.

To evaluate the significance of "reciprocal" ST segment depression resulting from coronary occlusion, 27 patients with single vessel coronary disease were studied with intravenous digital subtraction left ventriculography before and during angioplasty of the left anterior descending coronary artery. During balloon inflation, 13 patients developed inferior lead ST depression in addition to anterior lead ST elevation (Group 1), whereas the remaining 14 patients did not (Group 2). The degree of anterior lead ST elevation in Group 1 (5 mm) was greater than that in Group 2 (1.5 mm, p less than 0.001) as was the reduction in left ventricular ejection fraction (24% versus 13%, respectively; p less than 0.02). Anterior and apical regional shortening decreased in both groups similarly, but an additional decrease in anterobasal shortening was confined to Group 1 (from 38% to 21%; p less than 0.002). Despite the presence of inferior lead ST depression in Group 1, inferior regional shortening did not change and inferobasal contraction was enhanced (from 4% to 29%; p less than 0.01). Inferior lead ST segment depression during anterior descending coronary angioplasty reflects a greater degree of anterior wall ischemia. The concurrent preservation of inferior wall contraction and the augmentation of infero-basal shortening confirm that this electrocardiographic feature is a "reciprocal" phenomenon rather than a manifestation of remote ischemia.