GROSSENBESTIMMUNG AKUTER MYOKARDINFARKTE MIT TECHNETIUM-99M-PYROPHOSPHAT. VERGLEICH ZU CK(MB)-VERLAUF UND LETALITAT

While the technetium-99m-pyrophosphate scintigram enables diagnostic proof of acute myocardial infarction, its use in the evaluation of the extent of infarction has not been clearly established. This study, in 30 patients with acute myocardial infarction was, thus, undertaken to assess the relationship between the findings of the technetium-99m-pyrophosphate scintigram, with respect to infarct area and uptake pattern, the infarct size, as determined from the total CK and CK-MB curves, and the mortality. The scintigraphically determined infarct areas ranged between 1.7 and 29.3 cm²; the 20.2±6.0 cm² average for anterior wall infarction (n=18, range 7.4 to 29.3 cm²) was significantly greater (p<0.005) than the 8.3±5.3 cm² average for inferior infarction (n=12, range 1.7 to 15.8 cm²). Correlation coefficients between the scintigraphically and enzymatically determined infarct sizes for the entire population ranged from 0.71 to 0.80. Anterior infarctions correlated more closely (0.66 to 0.84) than inferior infarctions (0.46 to 0.66). The technetium-99m-pyrophosphate uptake pattern was focal in 20 patients and ring-shaped (doughnut) in ten. Infarcts with focal uptake patterns were significantly smaller than those displaying a doughnut pattern (12.2±6.4 vs. 24±4.0 cm², p<0.005). The infarct weight calculated from the CK-MB curve with application of individually determined disappearance rate for those infarcts displaying a focal uptake pattern was 34±29 grams while that associated with a doughnut uptake pattern was significantly greater at 86±25 grams (p<0.005). During the 18-month observation period there were six deaths; the average scintigraphic infarct area of 22.8±3.6 cm² in those who died was significantly greater (p<0.005) than that of the 13.8±8.2 cm² of the survivors. Of the non-survivors, five had a doughnut uptake pattern and one displayed focal uptake. In the 24 survivors, a focal uptake pattern was found in 19 and a doughnut pattern in five. Conversely, 19 of the 20 patients with a focal uptake pattern survived while only five of the ten patients with a doughnut pattern were alive after 18 months. Thus, comparison with the enzymatically determined infarct weight as well as the mortality indicates that the technetium-99m-pyrophosphate scintigram yields clinically relevant data with regard to infarct size. Since no patient with an infarct area of less than 17 cm² died within the 18-month observation period, designation of scintigraphically determined infarct size as small (<17 cm²) and large (>17 cm²) was enabled. The corresponding cut-off point between large and small infarctions as determined enzymatically has been designated at 65 grams. Accordingly, agreement was found in 70% (14 of 20 patients) with scintigraphically small infarcts and in 80% (8 of 10 patients) with scintigraphically large infarcts. The infarct areas of patients with doughnut uptake patterns exceeded 17 cm² such that a doughnut pattern can be considered diagnostic for a large infarct. In patients with focal uptake patterns, 70% (14 of 20) had small infarcts indicating that accurate assessment of a focal uptake pattern can only be achieved through planimetric quantification.