Comparison of radiological findings of chest x-ray with echocardiography in determination of the heart size.

Background: Heart size is an important and effective parameter in chest X-ray (CXR) interpretation. Studies indicate that, especially in middle-aged men, increased cardiothoracic ratio (CTR) is associated with ischemic heart disease (IHD) and increased rate of morbidity and mortality. The CXR is the most common imaging examination of the heart.

Objectives: A good quality posterior-anterior (PA) chest radiograph is an important indicator of the cardiac size. Nowadays, CXR has given its place to more advanced approaches such as two-dimensional echocardiography. However, CXR is still more accessible and feasible for most of the physicians. This study was designed to compare the findings of CXR and echocardiography in determination of the heart size.

Patients and methods: This cross-sectional study was carried out from 2006 to 2007. A total of 197 patients entered the study. The cases had been undergone PA CXR and 2-D echocardiography maximum within two days.

Results: Of participants, 24.9% had cardiomegaly according to the findings of CXR and 50.8% based on echocardiography. There was a statistically significant difference between the mean size of Right Ventricular End Diastolic Diameter in the patients with cardiothoracic ratio < 50% and ≥ 50% (P = 0.002) as well as Left Ventricular End Diastolic Diameter (P = 0.023). Also, a statistically significant difference was seen between echocardiography and CXR findings with regard to determination of the heart size (P = 0.003). Nonetheless, it is noteworthy that sensitivity and specificity of CXR findings in the diagnosis of cardiomegaly were 34%, and 84.5%, respectively.

Conclusions: CTR is the most common method of describing the heart size. Increased CTR in CXR is associated with poor prognosis, which is suggestive of importance and necessity of early diagnosis. Although CXR may not have the same diagnostic accuracy as echocardiography, its easy accessibility and high specificity in diagnosis of cardiomegaly is very helpful, which can play an important and a cost-benefit role, particularly in screening the enlarged heart size. Moreover, according to the statistics released by Medical Council of Iran, most of Iranian physicians are general practitioners and a few of them are cardiologist.