The aortic knob is a radiographic structure that is formed by the foreshortened aortic arch and a portion of the descending aorta.
The widest point of the ascending aortic knob was measured along the horizontal line from the point of the lateral edge of the trachea to the left lateral wall of the aortic knob (Fig.
ROC curve analyze was done to determine sensitivity and specificity of aortic knob value in subclinical atherosclerosis.
Analysis using the ROC curve has demonstrated that aortic knob of 41 mm constitutes the cut-off value for the presence of subclinical atherosclerosis with 71% sensitivity and 77% specificity (AUC-0.
In addition, our study is cross sectional and we cannot determine whether patients with increased aortic knob diameter will end up high rate of cardiovascular events.
Although this study is purely correlative and no causative conclusions can be drawn, it can be postulated that increased aortic knob width could reflect increased arterial stiffness in subjects with hypertension.