Geometrical characteristics of aortic root and left ventricular dysfunction in aortic stenosis: quantification of 256-slice coronary CT angiography

The purpose of this study is to analyze the geometrical characteristics of aortic root and left ventricular (LV) function in aortic stenosis (AS) using 256-slice coronary-computed tomography angiography (CCTA). Retrospective ECG-gated 256-slice CCTA data from 32 patients with tricuspid AS scheduled for aortic valve replacement, and 11 controls were analyzed. Aortic root geometry was measured using multiplanar reconstruction CT images. CCTA data set was transformed into 100 phases/cycle using motion coherence image processing. Systolic shortening (SS, mm/ms) and diastolic relaxation (DR, mm/ms(2)) in the circumferential and longitudinal directions on time curves of myocardial length were calculated, and were used as estimates of geometric LV function. Comparison of parameters was analyzed by Mann-Whitney U test. Receiver-operating-characteristic (ROC) analysis was performed to determine the optimal cutoff of parameters for differentiating AS patients. Height of the right coronary cusp was significantly lower for AS patients than controls (11.4 +/- 2.4 vs. 13.9 +/- 2.0 mm/m(2), p < 0.005). Verticallongitudinal SS was significantly lower for AS patients than for controls (1.7 +/- 0.8 vs. 2.7 +/- 0.7 mm/ms/m(2), p < 0.001). ROC analysis revealed optimal height of the right coronary cusp of 12.4 mm/m(2) and vertical-longitudinal SS of 2.4 mm/ms/m(2) for differentiating AS patients from controls, with C statistics of 0.82 and 0.85. In AS patients, ROC analysis revealed optimal vertical-longitudinal DR of 0.05 mm/ms(2)/m(2) for predicting patients with stroke volume index < 35 ml with C statistics of 0.93. Quantification of CCTA demonstrates that AS is characterized by small coronary cusps as aortic root remodeling and vertical-longitudinal LV dysfunction related to restrictive physiology.