⁹⁹Tc^m-sestamibi SPECT with combined dipyridamole and exercise stress in coronary artery disease

In order to evaluate the clinical value of ⁹⁹Tc^m-methoxyisobutylisonitrile (sestamibi) single photon emission computed tomography (SPEC T) after dipyridamole infusion in combination with low level bicycle exercise for the assessment of the presence, localization and extent of coronary artery disease (CAD), myocardial perfusion imaging was performed in 76 patients. Low level bicycle exercise was used to supplement the standard dipyridamole infusion protocol because of the lower incidence of noncardiac side effects. The results were compared to arteriographie findings obtained within 3 months of the SPECT studies. The overall sensitivity of detection of coronary artery disease (i.e. a luminal stenosis >50%) was 81%, specificity 80%, positive predictive value 96%, negative predictive value 40% and accuracy 82%. The diagnostic values for the detection of significant stenoses in the three major coronary arteries were: left anterior descending artery sensitivity 72%, specificity 87% and accuracy 76%; right coronary artery sensitivity 75%, specificity 90% and accuracy 80%; left circumflex coronary artery sensitivity 57%, specificity 85% and accuracy 71%. Scintigraphic evidence of multivessel disease was found in 31 (65%) patients with two- or three-vessel involvement assessed by arteriography. False negative test results were mainly found in patients with relatively mild CAD (one-vessel disease, branch and distal disease). ⁹⁹Tc^m-sestamibi SPECT after dipyridamole infusion in combination with low level bicycle exercise is shown to be a valuable diagnostic tool for the evaluation of CAD.