The electrocardiogram as a predictor of left ventricular systolic function: Correlation with gated SPECT imaging

Background: Left ventricular systolic function, expressed as ejection fraction (LVEF), is an important determinant of prognosis for cardiac disease, and is the basis for therapeutic decisions. Several imaging modalities are used for measuring LVEF. All require time, appropriate technology and professional attention, and most expose patients to small doses of radiation. We studied the correlation between surface electrocardiogram (ECG) and nuclear angiography in 673 patients. The purpose of our study was to determine whether normal ECG reliably predicts normal LVEF. Gated single-photon emission computed tomography (GSPECT) imaging was used as the reference. Methods and Results: A total of 673 patients (273 men, 400 women) with known or suspected coronary artery disease and normal ECGs underwent GSPECT Tc99m sestamibi stress tests (exercise stress for 405 patients, pharmacological stress for 268). Post-stress images were gated 30-60 minutes after stress. LVEF was determined using QGS Cedar-Sinai commercial software. Results were grouped according to type of stress (exercise or pharmacological) and the interpretation of perfusion imaging (normal or abnormal). LVEF was similar after exercise and pharmacological stress in patients with normal (69±7 vs 69±7) and abnormal (61±9 vs 62±10) stress perfusion. LVEF was < 45% (lower limit of normal) in only 7/673 patients (1%). Conclusions: Normal ECG reliably predicts normal LVEF measured by post-stress GSPECT. Absolute LVEF value is lower in patients with stress perfusion defects.