Cardiothoracic area ratio for evaluation of ejection fraction in patients

Abstract

AimThe advent of digital radiology and computerized workstations renders it very easy to measure cardiothoracic ratio (CTR) and cardiothoracic area ratio (CTAR) on chest radiographs. The aim of this study was to assess whether CTAR correlates with the left ventricular ejection fraction (EF) better than CTR in healthy individuals and patients with congestive heart failure. MethodThe study included 156 healthy individuals and 98 heart failure patients undergoing echocardiography and digital chest radiography. The CTR was calculated in the traditional manner, and the CTAR was taken as the ratio between the pixel counts of the cardiac area and whole thoracic area. ResultsThe traditional CTR showed an inverse correlation with ejection fraction in both healthy individuals (r = -0.13) and heart failure patients (r = -0.19). The CTAR showed an improved correlation (r = -0.32 for healthy individuals and r = -0.37 for heart failure patients). If it is assumed that an ejection fraction of 55% or more indicates normal cardiac function, a value of 50% or less for CTAR can be taken as normal. ConclusionDigital chest radiography is widely used as a popular technique for diagnosing various thoracic and cardiac diseases. Cardiomegaly is associated with an adverse outcome in patients with heart disease. Therefore, evaluation of heart size is an important clinical variable, and changes in heart size may be used to monitor and grade cardiac disease severity. Our findings suggest that the CTAR correlates better with cardiac function as assessed by the ejection fraction than the traditional CTR.

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