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<0.001) during handgrip exercise, while the LVEF decreased from 45±9% to 41±10% (P<0.01) in patients with acute myocardial infarction 4-7 weeks after episode, from 48±11 to 40±12% (P<0.001) in patients with old myocardial infarction, and from 52±9 to 42±9% (P<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.