Acute myocardial infarction imaged with ⁹⁹Tc(m) stannous pyrophosphate and ²⁰¹Tl: A clinical evaluation

Twenty six patients suspected of having acute myocardial infarction (AMI) underwent myocardial scintigraphy sequentially with ²⁰¹Tl and ⁹⁹(m)Tc stannous pyrophosphate ( ⁹⁹(m)Tc PP(i)). Of the 26 patients, 24 had AMI documented by enzyme and electrocardiographic changes. Nineteen had transmural and five had subendocardial myocardial infarctions. The remaining two patients had 'unstable angina pectoris'. The mean time from onset to imaging was 4 days. Of the 24 patients with AMI, 22 had positive ⁹⁹(m)Tc PP(i) scintigrams. In 20 the area of acute myocardial damage appeared to be the same by ⁹⁹(m)Tc PP(i) scintigram as by ECG; in two, the location could not be precisely determined. The two patients with negative ⁹⁹(m)Tc PP(i) scintigrams at the time of combined myocardial imaging had had positive ⁹⁹(m)Tc PP(i) images previously. In all 24 patients, the ²⁰¹Tl images were abnormal in at least the location suggested by the electrocardiogram. In seven patients, the area of decreased ²⁰¹Tl activity was grossly equal to the positive area on the ⁹⁹(m)Tc PP(i) images; in 15, the ²⁰¹Tl defect was definitely larger; and in two, the ²⁰¹Tl defect appeared slightly smaller. Although the ⁹⁹(m)Tc PP(i) and ²⁰¹Tl myocardial images provide different information, both are valuable in determining the overall integrity of the myocardium in patients with ischemic heart disease.