Routine Chest X-ray: Still Valuable for the Assessment of Left Ventricular Size and Function in the Era of Super Machines?

Abstract

Objectives: The development of technologically advanced, expensive techniques has progressively reduced the value of chest X-ray in clinical practice for the assessment of left ventricular (LV) dilatation and dysfunction. Although controversial data are reported on the role of this widely available technique in cardiac assessment, it is known that the cardio-thoracic ratio is predictive of risk of progression in the NYHA Class, hospitalization, and outcome in patients with LV dysfunction. This study aimed to evaluate the reliability of the transverse diameter of heart shadow [TDH] by chest X-ray for detecting LV dilatation and dysfunction as compared to Magnetic Resonance Imaging (MRI) performed for different clinical reasons.

Materials and methods: In 101 patients, TDH was measured in digital chest X-ray and LV volumes and ejection fraction (EF) by MRI, both exams performed within 2 days.

Results: A direct correlation between TDH and end-diastolic volumes (r = .75, P<0.0001) was reported. TDH cut-off values of 14.5 mm in females identified LV end-diastolic volumes >150 mL (sensitivity: 82%, specificity: 69%); in males a cut-off value of 15.5 mm identified LV end-diastolic volumes >210 mL (sensitivity: 84%; specificity: 72%). A negative relation was found between TDH and LVEF (r = -.54, P<0.0001). The above cut-off values of TDH discriminated patients with LV systolic dysfunction - LVEF <35% (sensitivity and specificity: 67% and 57% in females; 76% and 59% in males, respectively).

Conclusions: Chest X-ray may still be considered a reliable technique in predicting LV dilatation by the accurate measurement of TDH as compared to cardiac MRI. Technologically advanced, expensive, and less available imaging techniques should be performed on the basis of sound clinical requests.

Keywords: Cardiac MRI; chest X-ray; left ventricular dilatation; left ventricular dysfunction.

Figure 1

Postero-anterior chest X-ray projection where the measure of the transverse diameter of heart shadow (TDH) is reported. The measure was taken by drawing a line near the middle of the heart shadow and the spine and a line from the right border to that line. Another line from the left heart border, drawn to the middle, was added. The two lengths were added together to derive the TDH.

Figure 2

Relationship between the transverse diameter of heart shadow (TDH) and absolute values of left ventricular end-diastolic volume (LVEDV) by magnetic resonance imaging. A good positive correlation was found between the two indices (r = 0.75, P<0.0001).

Figure 3

Relationship between the transverse diameter of heart shadow (TDH) and left ventricular ejection fraction (LVEF) measured at magnetic resonance imaging. A negative correlation was detected between the two indices (r= - 0.54 P<0.001).