Measurement of left ventricular ejection fraction with ionic 113mIn and a cardiac probe

Left ventricular ejection fraction (LVEF) was measured with a cardiac probe (Nuclear Stethoscope, Bios Inc., Valhalla, New York) and 113mIn in 28 normal subjects and 86 patients with coronary artery disease (CAD). In 20 normal subjects 99mTC-RBCs were compared with 113mIn which binds to transferrin after IV injection. With 99mTc-RBCs, average LVEF was 57 +/- 7% (1 SD); with 113mIn, average LVEF was 55 +/- 8% (N.S.). Sequential measurements at different times over 60 min revealed good reproducibility. Comparison of LVEFs obtained using 99mTc-RBCs with a gamma camera and cardiac probe revealed a good correlation. The correlation coefficients were 0.92 in 25 patients with CAD and 0.95 in 10 patients with LV wall motion abnormalities. The LVEF obtained using a cardiac probe and 113mIn increased in 28 normals from 57 +/- 9% to 64 +/- 13% (P less than 0.001) during handgrip exercise, while the LVEF decreased from 45 +/- 9% to 41 +/- 10% (P less than 0.01) in patients with acute myocardial infarction 4-7 weeks after episode, from 48 +/- 11 to 40 +/- 12% (P less than 0.001) in patients with old myocardial infarction, and from 52 +/- 9 to 42 +/- 9% (P less than 0.001) in patients with angina pectoris. The cardiac probe and 113mIn provide a useful alternate means of determining left ventricular dysfunction in facilities where 99mTc and a gamma camera computer system are not readily available.