Correlation of resting electrocardiographic ST-T wave abnormalities with exercise thallium-201 stress testing in patients with known or suspected coronary artery disease

Abstract

Resting ST-T wave abnormalities have been associated with an increased risk of adverse cardiac events. Because increased myocardial ischemia represents a possible mechanism for these abnormalities, this study sought to determine whether patients with resting ST-T have greater myocardium in jeopardy as evidenced by stress-induced thallium-201 perfusion abnormalities. One hundred thirty-two consecutive patients not taking digitalis were prospectively studied with combined symptom-limited exercise testing and quantitative thallium-201 imaging. Patients with (n = 43) versus without (n = 89) resting ST-T were older and more frequently had diabetes mellitus. No difference between the 2 groups was seen with respect to gender, cardiac medications, systemic hypertension, prior myocardial infarction, or coronary artery bypass surgery. The results of stress testing were similar for the 2 groups with respect to maximal heart rate, maximal blood pressure, and METs achieved. The mean depth of ST depression was similar in the 2 groups, although patients without resting ST-T were more likely to have upsloping ST depresssion, and had a shorter duration of ST depression after exercise. With use of an 11 segment model analysis of stress and rest planar thallium-201 scintigrams, patients with versus without resting ST-T had significantly more scan segments showing redistribution defects (1.1 ± 1.7 vs 0.5 ± 1.1; p = 0.03) and total (both redistribution and persistent) defects (2.5 ± 2.5 vs 1.3 ± 1.9; p = 0.002). The lung-heart ratios (normal < 0.51) were similar in the 2 groups (0.44 ± 0.07 vs 0.43 ± 0.10; p = 0.44). Thus, patients with resting ST-T wave abnormalities who were not taking digitalis have more extensive stress-induced myocardial perfusion abnormalities on thallium-201 scintigraphy. This increased ischomic burden may be one explanation for the adverse outcome associated with resting ST-T wave abnormalities in patients with coronary artery disease.