Noninvasive detection and localization of coronary stenoses in patients: Comparison of resting dipyridamole and exercise thallium-201 myocardial perfusion imaging

Two noninvasive tests to detect and localize coronary stenoses were compared in a fully blinded protocol. Thallium 201 myocardial perfusion imaging (MPI) following maximal treadmill exercise and pharmacologic coronary vasodilation with intravenous dipyridamole (DP) was performed in 33 patients. Thallium 201 imaging defects in six myocardial perfusion regions were correlated with stenoses in their respective vascular distributions. Disease severity was determined with coronary arteriograms using a computer-assisted method, 198 myocardial regions were evaluated; 101 were supplied by at least one major artery with a ≥ 50% stenosis (luminal diameter narrowing). The sensitivity and specificity for detecting a ≥50% stenosis were 85% and 64% ( p < 0.005), respectively, for DP and 84% and 68% ( p < 0.005) for exercise-thallium 201 imaging. A particular combination of anterior and septal imaging defects was useful in detecting left anterior descending artery stenoses proximal to its first septal branch. DP administration was safe in this group of patients; however, 42% experienced transient chest pain. Although the overall sensitivity and specificity of the two methods were not significantly different, DP-MPI appeared more sensitive than exercise-MPI (70% vs 52%, p < 0.01) in detecting coronary stenoses in the 40% to 60% range. DP-thallium 201 MPI provides a useful alternative test for potential coronary disease patients unable to perform maximal exercise.