The aim of this study was to assess the potential role of 99mTc-tetrofosmin cardiac tomography in detecting totally occluded or severely stenosed coronary arteries.
Methods: Thirty-three patients (32 men, 1 woman; mean age, 52 +/- 9 yr) with chronic coronary artery disease (CAD) and left ventricular dysfunction (ejection fraction 40% +/- 12%) underwent resting 99mTc-tetrofosmin SPECT and coronary arteriography within 2 wk. Regional distribution of 99mTc-tetrofosmin activity was compared with the coronary anatomy. Tracer uptake was quantitatively analyzed in 22 segments for each patient. The activity in each segment was expressed as a percent of the peak activity.
Results: A significant relationship between the degree of coronary artery stenosis and 99mTc-tetrofosmin uptake was observed (p = -0.64, p < 0.001). Technetium-99m-tetrofosmin uptake was lower (p < 0.001) in segments with 100% coronary occlusion with poor collateral flow (53% +/- 17%) compared to segments supplied by a vessel with 50%-99% coronary stenosis (75% +/- 20%) or a normal noncritically stenosed artery (85% +/- 10%). Furthermore, 99mTc-tetrofosmin uptake was lower (p < 0.01) in segments with 100% coronary occlusion with poor (53% +/- 17%) compared to those with good collateral flow (70% +/- 20%).
Conclusion: These results demonstrate that quantitative analysis of resting 99mTc-tetrofosmin regional uptake detects the majority of segments supplied by occluded coronary arteries with poor collateral flow and suggest that this tracer may be helpful in the diagnosis of acute myocardial infarction.