Prediction of left ventricular ejection fraction using a unique method of chest x-ray and ECG analysis: A noninvasive index of cardiac performance based on the concept of heart volume and mass interrelationship

A reasonably accurate, simple, inexpensive, noninvasive method of determining ejection fraction (EF) is necessary to evaluate left ventricular function in epidemiologic studies and individual patients. Using the concepts of left ventricular mass reflected by precordial R wave summation (M̂) and left ventricular volume (V̂) estimated by chest roentgenography in 114 consecutive patients with myocardial disease undergoing left ventriculography, EF was predicted with the formula: EF = 63.74 - (2.16 · V̂) + (0.34 · M̂); R² = 0.69; standard error of the estimate (SEE) = 11. Because angiographic inferior wall motion (IWM) abnormalities significantly affected the results, but inferior Q waves were usually only present in patients having one infarct, a noninvasive technique to predict the presence of inferior wall motion abnormality (IM̂A) in patients having multiple infarcts was developed and based on the relationship of precordial R wave summation (M̂) and roentgenographic heart volumenometry (V̂). By combining V̂, M̂, and IM̂A (which predicted IWM) to determine EF, multiple linear regression analysis showed that EF = 67.30 - (1.56 · V̂) + (0.23 · M̂) - (14.18 IM̂A) (R² = 0.77; SEE = 9). Prospective validation of the formula was then done in 139 consecutive individuals, with R² = 0.49 and SEE = 9. This study demonstrates that routinely performed, simple, inexpensive clinical tests provide data that can be combined by multiple regression analysis to predict resting EF in patients with heart disease affecting the left ventricle. This unique method may allow inexpensive ventricular function screening in large population studies and in addition might provide an independent index of myocardial performance for clinical use, since it reflects the amount of contractile mass per unit of left ventricular volume. The formula can be adapted to a nomogram or hand-held calculator.