This is a cross-sectional study carried out to study the validity of the cardiothoracic ratio as a predictor of cardiac
enlargement. The study involved 150 patients attending Alsader Teaching Hospital for various cardiac symptoms.
The cardiothoracic ratio (CTR) was measured for 150 posterior anterior (PA) view chest x-ray. Left Ventricular
Internal Dimension in systole (LVIDs) and Left Ventricular Internal Dimension in diastole (LVIDd) were measured
by 2D echocardiography (through the parasternal axis) in patients who have a PA view chest x-ray within the same
week. The study showed that the ability of chest x-ray (by measuring CTR) to measure cardiac size in patient with
cardiomegaly in comparison to echocardiography (by measuring LVIDd) is high (sensitivity 85.71%), while the
ability of chest x-ray to exclude cardiomegaly in comparison to echocardiography is low (specificity 13.79%).
Furthermore, the ability of chest x-ray to detect (sensitivity) or exclude (specificity) cardiomegaly in comparison to
echocardiography (by measuring LVIDs) was 90.47% and 17.24% respectively. The study found significant
correlation between CTR and LVIDd (using Pearson correlation), and there was no significant correlation between
CTR and Body mass index (BMI). The study recommended that because it is easy and cheap to measure the CTR by
the chest x-ray for any patient in the emergency department, it can be regarded as a preliminary measure to the size
of the heart, but echocardiographic measurements remained the most accurate.