Technetium-99m Stannous Pyrophosphate, Regional Myocardial Blood Flow and Creatine Phosphokinase Depletion

The dual radionuclide myocardial distributions of imaging agents potassium43 (49K) and technetium-99m stannous pyrophosphate ('9mTc-PYP) were studied in a 24-hour closed chest canine infarct preparation. In multiple myocardial biopsies in 20 dogs, tissue levels of both radionuclides were compared to either an index of tissue viability (myocardial creatine phosphokinase [CPK] depletion), or to estimates of regional myocardial blood flow as measured by the microsphere technique. Myocardial 4K uptake in the ischemic and infarcted zone correlated well with both CPK depletion (r = 0.73) and microsphere estimates of relative blood flow. The correlation with microspheres was excellent in the transmural sample (r = 0.93) as well as endocardial (r= 0.97) and epicardial (r = 0.86) portions. On the other hand, "tmTc-PYP myocardial uptake did not correlate with the extent of CPK depletion. Maximal uptake was frequently noted in border zones with only moderate CPK depletion,