Radiographic measurements of cardiac size as predictors of outcome in patients with dilated cardiomyopathy

Background: Cardiac dilatation is a predictor of poor outcome in patients with dilated cardiomyopathy, Whereas cardiac chamber dimensions or volumes can be assessed by various noninvasive and invasive techniques, simple chest radiography also may provide a valuable assessment of cardiac size. Methods and Results: To determine the relative power of radiographic heart measurements for predicting outcome in dilated cardiomyopathy, we retrospectively studied 88 adult patients with chest radiographs obtained within 35 days of echocardiography. Standard radiographic variables were measured for each patient, and the cardiothoracic (CT) ratio, frontal cardiac areal and volume were calculated. During a mean 4.1-year follow-up, 62 of the 88 (71%) patients died. CT ratio was the best predictor of mortality among the radiographic cardiac measurements. By multivariate analysis, a model including echocardiographic ejection fraction, New York Heart Association (NYHA) functional class, and history of heart failure was highly predictive of survival. When added to this model. CT ratio also was independently associated with mortality, but not radiographic cardiac area or volume. When radiographic variables were each added to CT ratio. they did not add incremental predictive value to the model that included CT ratio alone. Echocardiographic measurement of left ventricular (LV) size, especially when indexed for body size, was independently predictive of outcome, but it did not supersede the predictive power of CT ratio. Conclusion: The simply derived radiographic CT ratio is a useful predictor of outcome in patients with dilated cardiomyopathy and compares favorably with other clinical and selected echocardiographic variables.