The comparative value of exercise echocardiography and 99m Tc MIBI single photon emission computed tomography in the diagnosis and localization of myocardial ischaemia

To determine the relative value of exercise two-dimensional echocardiography and 99m Tc methoxyisobutylisonitrile single photon emission computed tomography (MIBI SPECT) for the detection of myocardial ischaemia, 103 consecutive patients with either proven or suspected coronary artery disease, who were referred for perfusion scintigraphy, were studied by a combination of the two techniques during the same symptom-limited upright bicycle exercise test. Appropriate echocardiographic images were recorded both at rest and immediately post-exercise and subsequently analysed by means of digital cine loop processing. Both echocardiographic and MIBI SPECT images were visually analysed. For each technique, three different responses to exercise were defined: normal (absence of rest and exercise abnormalities), ischaemic (transient scintigraphic perfusion defects and transient wall motion abnormalities during exercise echocardiography); and fixed abnormalities (fixed scintigraphic perfusion defects; echocardiographic wall motion abnormalities at rest without worsening after exercise). To allow a valid comparison of each technique in localizing ischaemia, the left ventricle was divided into the following six major regions for both methods: anterior, posterolateral, inferior, interventricular septum (subdivided in anterior and posterior septum) and apex. Eleven of the 103 patients had to be excluded from the final analysis because of unsatisfactory examinations: seven with non-interpretable exercise echocardiograms and four with non-interpretable MIBI SPECT images. The response to exercise was concordantly classified by both techniques in 84% ofpatients (k = 0·18). Exercise echocardiography revealed the presence of ischaemia in 38 and MIBI SPECT in 45 patients (agreement = 77%). When regional analysis was performed, concordance of exercise echocardiography and MIBI SPECT was observed in 91% of the 552 regions (k = 0·81), while agreement for the presence of myocardial ischaemia was lower (72%), with a trend for a higher occurrence of transient perfusion defects in posterolateral and inferior regions and in patients with previous myocardial infarction. In the 30 patients without previous myocardial infarction who underwent coronary angiography, the sensitivities of exercise ECG, echocardiography and SPECT for the diagnosis of coronary artery disease (diameter stenosis ≥ 50%) were 56%, 70% and 77%, respectively.