Acute myocardial infarction delineated by noninvasive thallium-201/technetium-99m pyrophosphate tomography

Assessment of acute myocardial necrosis after cardiopulmonary resuscitation and cardioversion by means of combined thallium-201/technetium-99m pyrophosphate tomography

Diagnosis of acute myocardial necrosis by means of conventional electrocardiographic criteria or the release of cardiac enzymes is often difficult or even impossible in patients with out-of-hospital cardiac arrest due to ventricular fibrillation with subsequent cardiopulmonary resuscitation including several DC countershocks. Simultaneous thallium-201/technetium-99m pyrophosphate (PYP) tomography was prospectively applied to 57 patients without typical clinical or electrocardiographic signs of acute myocardial infarction within 48 h after successful resuscitation from out-of-hospital cardiac arrest. Scintigraphic evidence of acute necrosis was present in 23/57 patients (40%). Increased 99mTc-PYP uptake in the pericardial tissue was found in 24 patients (42%). Maximal creatine kinase (CK) concentration was increased in 50/57 patients (88%). CK-MB activity averaged 68+/-52 U/l in patients with positive and 17+/-13 U/l in patients with negative tomograms (P<0.0005), demonstrating the validity of 201Tl/99mTc-PYP tomography. It may be concluded that simultaneous 201Tl/99mTc-PYP tomography is a valuable tool for evaluation of myocardial necrosis after cardiopulmonary resuscitation including DC countershock. Acute myocardial necrosis, as indicated by scintigraphy, represents a potential trigger for the occurrence of ventricular fibrillation. Therefore, 201Tl/99mTc-PYP tomography can be recommended in order to guide further diagnostic and therapeutic interventions in patients after cardiopulmonary resuscitation in whom the underlying cause of the occurrence of ventricular fibrillation is obscure.

Comparison in acute myocardial infarction of anisoylated plasminogen streptokinase activator complex versus heparin evaluated by simultaneous thallium-201/technetium-99m pyrophosphate tomography

In a subgroup of 45 patients with acute myocardial infarction (AMI) from the German multicenter trial of anisoylated plasminogen streptokinase activator complex (APSAC) (n = 20) versus heparin (n = 25), simultaneous thallium (TI)-201 technetium (Tc)-99m pyrophosphate (PYP) tomography was initiated to elucidate a possible benefit of APSAC over heparin. Findings in the 2 treatment groups were similar with respect to TI-201 defect score, relative scintigraphic infarct size, and in keeping with the main group coronary artery patency, global ejection fraction and maximal creatine kinase level. However, 2 different TI-201/Tc-99m PYP accumulation patterns within the area of infarction (homogeneous, group A; inhomogeneous, group B) were identified. Both treatment groups were similar with regard to the frequency of the homogeneous and inhomogeneous pattern. In comparing the 2 accumulation patterns, creatine kinase peaked earlier in group A than in group B, and global left ventricular ejection fraction was significantly higher in group A than in group B. In Group A, 30 of 31 patients and in group B 7 of 11 patients had a patent infarct-related vessel (p < 0.025). TI-201 defect score was lower in group A than in group B. Likewise, relative size of the infarction as determined from Tc-99m PYP images was significantly lower in group A than in group B. Fifteen patients experienced cardiogenic shock or severe heart failure. Patients in group B had a higher incidence of these in-hospital complications than patients in group A (92 vs 12%, p < 0.0005). Scintigraphic infarct size and TI-201 defect score were greater in patients with the aforementioned clinical events.(ABSTRACT TRUNCATED AT 250 WORDS)

Relation of technetium-99m pyrophosphate accumulation to time interval after onset of acute myocardial infarction as assessed by a tomographic acquisition technique

Technetium-99m pyrophosphate (Tc-99m PYP) myocardial scintigraphy was performed in 110 clinically stable patients with acute or healed acute myocardial infarction (AMI). Tomography was performed 12 hours to 7 days (group A), 7 to 30 days (Group B), 1 to 6 months (Group C) and after greater than 6 months (group D) after AMI. All 40 patients in group A, 9 of 31 in group B, 1 of 22 in group C, and no patient (0 of 17) in group D had a pathologic Tc-99m PYP tomogram. Relative Tc-99m PYP accumulation within the area of infarction was measured as infarct zone to blood pool ratio, which decreased significantly (p less than 0.001) from group A (1.54 +/- 0.39) to group B (0.89 +/- 0.24), group C (0.8 +/- 0.19) and group D (0.76 +/- 0.13). These data were confirmed by sequential scintigraphy in 17 patients. It is concluded that a persisting Tc-99m PYP uptake is rarely found greater than 1 month after AMI using tomographic imaging techniques in clinically stable patients with coronary artery disease. Positive results on Tc-99m PYP tomography are a reliable indicator of AMI. Thus, Tc-99m PYP tomography is not only a sensitive but also a specific imaging technique for AMI, which might be especially useful for diagnosis of reinfarction.