PURPOSE: Chest X-ray is one of the most widely used methods for patient evaluation. However, its value in predicting left, right ventricular volumes and function is still controversial. To evaluate the reliability of a simple chest X-ray measurement (transverse diameter of the heart shadow [TDH]) in detecting LV dysfunction, independently measured by cardiac magnetic resonance imaging (MRI), which represents a gold standard for LV volumes.
METHODS: Consecutive in-patients with ischemic heart disease (n° = 50), cardiomyopathy (n° = 26), valvular heart disease (5), acute myo-pericarditis (6), hypertrophic cardiomyopathy (2), arrhythmias (n° = 12) underwent cardiac MRI and chest X-ray for clinical purposes. All patients were under stable clinical conditions. The TDH (in mm) was measured in digital PA chest X-ray by an expert chest radiologist as the sum of the widest portions of the heart to the right and to the left of the midline of the spine. LV volumes and ejection fraction EF were measured on cardiac MRI by independent cardiologists; readers were blind to each other measurements.
RESULTS: A correlation was found between TDH measures and absolute end diastolic volumes (r =.77, p <0.0001). A TDH cut-off value of 14.5 mm in females was able to identify correctly an increase in LV end-diastolic volume >150 ml (sensitivity of 82 %, specificity of 70%). A cut-off value of 15.5 mm in males identified an increase in LV end-diastolic volume >210 ml (sensitivity of 84 %, specificity of 75%). The above cut-off values of TDH were able to discriminate patients with LV dysfunction (EF <35%) with a sensitivity and a specificity of 67 and 53% in females, 80 and 59 % in males.
CONCLUSION: In an unselected patient population undergoing cardiac MRI, the simple measurement of transverse diameter of heart shadow is a good predictor of LV dilatation.
CLINICAL IMPLICATIONS: TDH provides only a fair assessment of LV dysfunction and other techniques are needed to obtain a reliable estimate of the degree of LV functional impairment.
DISCLOSURE: Renato Prediletto, None.