Assessment of myocardium at risk with computerized vectorcardiography and technetium-99m-sestamibi-single photon emission computed tomography during coronary angioplasty.

OBJECTIVE

To compare the myocardium at risk (MAR) as estimated by computerized vectorcardiography (cVCG) with MAR determined by Tc-99m-sestamibi-SPECT using coronary angioplasty as the model for transient transmural ischemia in humans.

METHODS AND RESULTS

In 37 patients with stable angina pectoris, cVCG was recorded continuously during coronary angioplasty. The scintigraphic defect was quantified using an automated software program (CEqual). The ST vector magnitude (ST-VM) and the ST change vector magnitude (STC-VM) correlated well with MAR estimated by scintigraphy, ST-VM (r = 0.71, p < 0.001) and STC-VM (r = 0.84, p < 0.001). All patients with STC-VM <50 microV during occlusion had defects of less than 10% of the left ventricle.

CONCLUSION

1. ST-VM and STC-VM give a reasonable useful estimate of MAR size during transient coronary occlusion. 2) STC-VM <50 microV is a reliable limit to identify patients with MAR size less than 10%. 3) ST-VM does not add information to STC-VM with respect to detection of ischemia. 4) The existence of collateral vessels has great impact on both ST-vector changes and scintigraphic imaging of myocardial ischemia.