Unreliability of cardiothoracic ratio as a marker of left ventricular impairment: comparison with radionuclide ventriculography and echocardiography.

Abstract

The size of the heart assessed by cardiothoracic ratio on chest radiography is often used as a screening test for the presence of heart failure and for assessing its severity. We compared cardiothoracic ratio (CTR), left ventricular ejection fraction (LVEF) from radionuclide ventriculography, and left ventricular dimensions from echocardiography in a population of 91 patients (aged 60.4 (SD 9.6) years) with a diagnosis of chronic heart failure. There was a weak relation between CTR and LVEF (R = 0.33) and fractional shortening from echocardiography (R = 0.22). LVEF and fractional shortening correlated more closely (R = 0.55). No measure of left ventricular function correlated with exercise capacity as measured by peak oxygen consumption. For the group of patients with a normal fractional shortening (n = 17), the left ventricle was dilated in all but two (mean end diastolic dimension 5. 9 (0.7) cm). The two with normal dimensions had a low ejection fraction. For the 12 patients with a CTR in the normal range, the left ventricular end diastolic dimension was only slightly smaller than for the rest (6.2 (0.9) v. 6.9 (1.2); p = 0.045). Chest radiography is not a reliable indicator of the degree of left ventricular dysfunction. Echocardiography and radionuclide ventriculography are more appropriate investigations for assessing cardiac function.