Left Ventricular Performance after Myocardial Infarction Assessed by Radioisotope

Radioisotope angiocardiography was performed by peripheral venous or pulmonary arterial injection of 99mTc pertechnetate in 64 patients with acute myocardial infarction. End-diastolic volume determined with this technic averaged 101 + 7 (+ SEM) ml/m2 and was elevated (>90 ml/m2) in 47 patients. Initial ejection fraction (EF) averaged 0.38 + 0.03 and was reduced (<0.52) in 58 patients. The extent of diameter shortening at the minor left ventricular equator determined from the isotope angiocardiograms was depressed in 51 patients, a reduction which was not consistently related to the site of infarction determined electrocardiographically. In 53 survivors EF averaged 0.40 + 0.02, compared to 0.26 + 0.07 (P < 0.05) in 11 patients who died within 1 month. EF correlated inversely with infarct size estimated by analysis of serial changes in serum CPK activity (r = 0.71, n = 42). Of the 64 patients with acute infarction, 47 exhibited abnormal wall motion detectable by the radionuclide technic and confirmed by radarkymography. Serial radioisotope angiocardiograms (6 hours-i month) showed improvement of cardiac function in 30 of 55 patients, with no change in 12, and deterioration in 13 patients. Results obtained indicate that radioisotope angiocardiography performed by peripheral intra-