Accuracy of detection of myocardial viability and residual infarct vessel stenoses with rest Tl-201 and adenosine Tc-99m sestamibi imaging after coronary reperfusion in dogs with experimental acute myocardial infarction.
BACKGROUND
We sought to determine whether a dual-isotope imaging strategy (rest thallium 201/stress technetium 99m sestamibi) might be useful for assessing myocardial viability and residual ischemia in the infarct zone very early after reperfusion.


RESULTS
Fifteen open-chest dogs had left anterior descending coronary artery occlusion for 60 minutes, followed by full reperfusion (group 1, n = 8) or reperfusion through a residual critical stenosis (group 2, n = 7). Tl-201 was injected at rest 45 minutes after reperfusion, and initial and 2-hour redistribution images were acquired. Tc-99m sestamibi was then injected during vasodilator stress, followed by imaging. Infarct size was similar in both groups (risk area, 21% +/- 4% vs 22% +/- 3%). Rest Tl-201 defect count ratios (left anterior descending coronary artery/left circumflex artery) were comparable (0.71 +/- 0.03 vs 0.74 +/- 0.02) and reflected infarct size. With vasodilation, Tc-99m sestamibi defect count ratio in group 1 (0.71 +/- 0.02) was comparable to rest Tl-201 and was significantly greater than in group 2 (0.62 +/- 0.02) with residual stenoses (P <.01). Although vasodilator Tc-99m sestamibi imaging unmasked the presence of residual stenoses, Tc-99m sestamibi uptake underestimated their functional severity (flow ratio, 0.38 +/- 0.03).


CONCLUSIONS
Dual-isotope imaging very early after reperfusion may have limited utility for detecting residual stenoses in the infarct zone. Underestimation of the flow disparity by Tc-99m sestamibi may make the detection of stenoses more difficult, and impaired flow reserve after ischemic insult may complicate the detection of fully reperfused segments.
Takehana
Kazuya
K
Experimental Cardiology Laboratory, Cardiovascular Division, Department of Internal Medicine, University of Virginia Health System, Charlottesville, VA 22908-0500, USA.
Beller
George A
GA
Ruiz
Mirta
M
Petruzella
Frank D
FD
Watson
Denny D
DD
Glover
David K
DK
D000818:Animals; D023921:Coronary Stenosis / Q000000981:diagnostic imaging*; D004285:Dogs; D007089:Image Enhancement / Q000379:methods*; D009203:Myocardial Infarction / Q000150:complications / Q000000981:diagnostic imaging*; D015428:Myocardial Reperfusion Injury / Q000000981:diagnostic imaging* / Q000209:etiology; D017682:Myocardial Stunning / Q000000981:diagnostic imaging* / Q000209:etiology; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D017256:Technetium Tc 99m Sestamibi; D013793:Thallium; D014022:Tissue Survival
D019275:Radiopharmaceuticals; C027549:thallium chloride; D017256:Technetium Tc 99m Sestamibi; D013793:Thallium