Thallium and indium antimyosin dual-isotope single-photon emission tomography in acute myocardial infarction to identify patients at further ischaemic risk.

Dual-isotope single-photon emission tomography (SPET) with indium-111 antimyosin and thallium-201 chloride was performed in 54 patients with acute myocardial infarction (AMI) to detect the location and extent of myocardial necrosis (antimyosin) and viable myocardium (201Tl). All patients underwent intravenous thrombolytic therapy with either streptokinase (1.5 million units/90 min) or tissue plasminogen activator (80 mg/90 min). Sensitivity in detecting MI was 91% (49/54 patients). With regard to dual-isotope SPET patterns, patients were divided into three groups: match, i.e. antimyosin uptake in segments with thallium defect (n = 8); mismatch, i.e. no uptake of either of the nuclides in corresponding segments (presence of perfusion abnormalities in the absence of antimyosin uptake) (n = 5); and overlap, i.e. thallium uptake in segments with uptake of antimyosin (n = 41). Coronary angiography and thallium exercise tests were performed in 40 and 45 patients, respectively, 5-14 days after MI. Exercise-induced ischaemia occurred in 66% of patients with overlap, 14% with match and 0% with mismatch (P < 0.05 for overlap vs other groups). If, however, major in-hospital complications (sudden cardiac death, severe arrhythmias; five overlap, three overlap in addition to match/mismatch, two match, two mismatch) were included in the statistical analysis, there was no significant difference between the three groups (P = NS). Thus, although the dual-isotope pattern "overlap" identifies a subgroup of patients with a substantial amount of residual viable tissue after MI and a high probability of exercise-induced ischaemia, this criterion is of limited value in assessing short-term prognosis.(ABSTRACT TRUNCATED AT 250 WORDS)