Aortic knob width reflects left ventricular diastolic function assessed by gated myocardial perfusion single photon emission computed tomography in patients with normal myocardial perfusion

Background Aortic knob width on chest radiography represents the extent of aortic dialation and tortuosity of the aortic arch. We tested the hypothesis that aortic knob width reflected left ventricular (LV) diastolic function assessed by gated myocardial perfusion single photon emission computed tomography (SPECT) in patients with normal myocardial perfusion. Methods One hundred and thirty patients with preserved LV ejection fraction and normal myocardial perfusion were enrolled in this study. Aortic knob width 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. The peak filling rate (PFR) and the one-third mean filling rate (1/3 MFR) were obtained as LV diastolic parameters. Results There were 114 male and 16 female patients. Age ranged from 43 to 88 years (69.9 +/- 8.9 years). Aortic knob width ranged from 24.2 to 53.4 mm (37.6 +/- 5.7 mm). There was a significant correlation between age and aortic knob width (r = 0.34, p < 0.001). Aortic knob width was inversely correlated with both PFR (r = -0.53, p < 0.001) and 1/3 MFR (r = -0.42, p < 0.001). Multivariate linear regression analysis revealed that serum creatinine (beta = -0.16, p = 0.045) and aortic knob width (beta = -0.45, p < 0.001) were significant predictors of PFR, and that age (beta = -0.20, p = 0.02) and aortic knob width (beta = -0.33, p < 0.001) were significant predictors of 1/3 MFR. Conclusion Our data suggested that aortic knob width on chest radiography was a simple marker of LV diastolic function in patients with normal myocardial perfusion.