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

Background-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 Methods-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. Results-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). Conclusions-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.