4.13: Non-invasive stress testing of myocardial perfusion defects: Head-to-head comparison of thallium-201 SPECT to MRI perfusion

Abstract

This study evaluated the diameters and distensibility of the aortic root as well as the degree of aortic regurgitation (AR) and its effect on left ventricular (LV) function in patients 8.2 ± 3.1 years after they underwent the Ross procedure, with a comparison of these parameters between patients and matched healthy subjects.Eighteen Ross procedure patients (16 male patients, age [mean ± SD] 19.2 ± 3.8 years) and 18 matched healthy subjects (16 male patients, age [mean ± SD] 19.7 ± 4.2 years) underwent magnetic resonance imaging. Measurements for diameters (at 4 levels) and the distensibility of the aortic root were performed using a steady-state free precession sequence. Aortic flow was assessed with a velocity-encoded phase-contrast sequence. Left ventricular systolic function was assessed with a gradient-echo sequence in the short-axis plane. Comparison of parameters was performed using the Mann-Whitney U test. Correlations between diameters, distensibility, AR fraction, and LV systolic function were expressed with Spearman rank correlation coefficients. Linear regression analysis was used to identify predictors of LV systolic dysfunction.Aortic root diameters were increased in Ross procedure patients as compared with healthy subjects (mean difference 6.3-11.6 mm, P ≤ .02 at all 4 levels). Distensibility of the aortic root was lower in patients (1.9 ± 1.1 vs 7.8 ± 3.3 mm Hg−1, P < .01). An AR fraction >5% was present in 14 of the 18 patients (mean AR fraction 8% ± 5% vs 1% ± 1%, P < .01). Left ventricular ejection fraction was lower in patients (50% ± 6% vs 57% ± 6%, P < .01). Dilatation, decreased distensibility, and AR fraction were correlated with impaired LV systolic function (P < .05 for all). The AR fraction predicted impaired LV systolic function (P < .01).Magnetic resonance imaging shows dilatation and decreased distensibility of the aortic root, AR, and consequent impaired LV systolic function in patients after the Ross procedure.