Association between aortic knob width and invasively measured aortic pulse pressure.

BACKGROUND: Aortic knob width (AKW), which can be measured easily in simple radiography, is associated with the degree of dilatation and tortuosity of the aortic arch. Pulsatile stress influences aortic geometry. This study was carried out to investigate whether AKW can represent invasively measured aortic pulse pressure (APP).

METHODS: A total of 252 patients who underwent invasive coronary angiography (ICA) for the evaluation of coronary artery disease were enrolled. AKW was defined as the perpendicular length from the lateral margin of the main bronchus to the most prominent edge of the aortic knob on chest radiography. APP was measured at the ascending aorta using a pigtail catheter immediately before ICA.

RESULTS: When patients were divided into two groups according to the median value of APP (69 mmHg), AKW was significantly greater in patients with higher APP (≥69 mmHg) than in those with lower APP (<69 mmHg) (40.6±4.9 vs. 38.1±4.2 mm, P<0.001). There was a positive linear correlation between APP and AKW (r=0.207, P<0.001). In multiple linear regression analysis, the significant association between APP and AKW remained even after controlling for the confounding factors, including age, sex, height, heart rate, smoking status, left ventricular ejection fraction, and left ventricular end-diastolic dimension (β=0.131, P=0.031).

CONCLUSION: Greater AKW on chest radiography was independently predictive of increased APP in patients undergoing elective ICA. The results of this study suggest that AKW can be useful as a simple surrogate marker of APP.