Elastic aortic properties in patients with X syndrome

Elastic properties of the aorta represent an important determinant of left ventricular function and coronary blood flow but there are few data about aortic stiffness in patients with X syndrome.

To investigate the elastic aortic proprieties (aortic stiffness and distensibility) and arterial wall motion velocities as measured by tissue Doppler imaging (TDI) in patients with cardiac X syndrome.

Fifteen patients with X syndrome (typical chest pain and angiographically normal coronary arteries associated with a positive exercise test) were enrolled in the study. The control group consisted of 15 healthy patients. The aortic elastic indexes, namely distensibility (cm(2) dyne(-1)) and stiffness index (β index) were calculated from M-mode echocardiographically-derived thoracic aortic diameters using accepted formulae, and TDI parameters were measured on the wall of the ascending aorta 3 cm above the aortic valve. Anterior wall aortic expansion velocity (S), early (E) and late (A) diastolic retraction velocity and peak systolic strain were determined.

Aortic elastic proprieties were more impaired in the syndrome X group than in the control group. Aortic distensibility was significantly lower in the syndrome X group (3.2 ± 1.3 vs. 7.95 ± 4 cm(2) dyne(-1), p<0.001), while stiffness index was higher (7.3 ± 2.1 vs. 4.1 ± 1.6, p<0.001) than in the control group. Peak systolic (S) and diastolic waves (E and A waves) of the aortic wall TDI were similar in patients and controls (S wave: 5.7 ± 1.6 cm/s vs. 5.8 ± 1.6 cm/s, E wave: -4.8 ± 2.0 vs. -4.1 ± 2.0 cm/s; A wave: -4.32 ± 2.1 vs. -4.76 ± 1.8 cm/s) while tissue strain of the aortic wall was lower in patients with X syndrome than controls (-12.80 ± 7% vs. -22.3 ± 5.9%, p<0.00001).

Deterioration in aortic elasticity properties in patients with cardiac syndrome X suggests that this disease may be a more generalised disturbance of the vasculature.