Comparison of Dipyridamole-Echocardiography Test and Exercise Thallium-201 Scanning for Diagnosis of Coronary Artery Disease

Abstract

Two noninvasive tests to detect and localize coronary stenoses were compared in a fully blinded protocol. Thallium-201 myocardial perfusion imaging during cycloergometer exercise (TET) and high dose dipyridamoleechocardiography test (DET: 2-D echo monitoring with dipyridamole infusion, up to 0.84 mg/kg in 10 min) were performed in 61 patients with chest pain syndrome. Criteria of positivity were: for TET, a reversible defect of perfusion, as quantitatively assessed by the postexercise and redistribution images; for DET, a transient dyssynergy of contraction, absent or of a lesser degree in resting conditions. All patients underwent coronary angiography; 38 had significant coronary artery disease (at least one major artery with >70% luminal diameter narrowing). The sensitivity for detecting angiographically assessed coronary artery disease was 86% for TET and 79% for DET (p = NS); the specificity was, respectively, 56 and 100% (p < 0.01). In 27 out of the 30 patients in whom both TET and DET yielded positive responses, the same myocardial region was involved. In conclusion, DET represents a reasonable diagnostic alternative to TET, showing a similar sensitivity and a higher specificity for the detection of angiographically assessed coronary artery disease. DET needs an acceptable acoustic window to be performed: it is however less expensive than TET, requires a much shorter imaging time and can also be performed in patients unable to exercise.