Background: Myocardial perfusion imaging in conjunction with dipyridamole low-level exercise stress has proved its value in the evaluation of patients with coronary artery disease (CAD). Simultaneous wall motion analysis by two-dimensional (2D) echocardiography may provide additional information beyond that obtained by myocardial perfusion imaging alone. The purpose of this study was to compare 99mTc-labeled sestamibi single-photon emission computed tomography (SPECT) and 2D echocardiography for the evaluation of CAD according to a dipyridamole low-level bicycle exercise stress protocol.
Methods and results: We studied 35 consecutive patients referred for the evaluation of chest pain who had undergone coronary arteriography. 99mTc-labeled sestamibi SPECT and 2D echocardiography agreed in 27 patients (80%) studied for overall detection of CAD. On a segmental basis, agreement was found between SPECT and 2D echocardiography in 124 (73%) of 170 segments (Cohen's kappa = 0.43). The accuracy of the combined assessment of myocardial perfusion and echocardiographic wall motion in detecting CAD was 86%, which was not different from the accuracy of SPECT alone (80%; difference not significant) but significantly higher than for 2D echocardiography alone (71%; p = 0.03). In the detection of individual coronary artery stenoses, SPECT had a significantly higher accuracy for detecting left anterior descending coronary artery lesions than had 2D echocardiography (80% vs 60%; p < 0.01); combining the two method did not improve the accuracy (80%). The combined assessment slightly improved the accuracy for detecting left circumflex coronary artery stenoses from 71% to 83% (p = 0.05).
Conclusion: The combined simultaneous assessment of myocardial perfusion by 99mTc-labeled sestamibi SPECT and wall motion by 2D echocardiography did not significantly improve overall accuracy over that obtained by 99mTc-labeled sestamibi SPECT alone. Therefore 99mTc-labeled sestamibi SPECT with dipyridamole low-level exercise stress appears the preferred imaging modality for the evaluation of patients with CAD.