973Aortic valve area, stroke volume, left ventricular hypertrophy, remodeling and fibrosis in aortic stenosis assessed by cardiac MRI. Comparison between high and low gradient, and normal and low flow aortic stenosis

Aims: To assess the accuracy of the recently proposed echocardiographic classification system of aortic stenosis (AS), and to evaluate differences between patients with high (HG) and low gradient (LG) and normal (NF) and low flow (LF) AS in terms of AS severity, LV remodeling and fibrosis using cardiovascular magnetic resonance (CMR). Methods and results: 128 consecutive patients (73 ± 11 years, 95 male) with aortic valve area (AVA) <0.6 cm/m2 and ejection fraction >50% by echocardiography underwent evaluation of planimetric AVA, phase contrast indexed stroke volume (SVI), left ventricular hypertrophy, and focal fibrosis by CMR. Using <40 mm Hg, and SVI <35 ml/m2 as criteria for LG and LF respectively, 69(54%) patients were HG/NF, 28(22%) HG/LF, 17(13%) LG/NF, and 14(11%) LG/LF AS. Measurements of LVOT area, SVI and AVA correlated well between echocardiography and CMR (r = 0.7, 0.61, 0.65, respectively; p < 0.001 for all). Planimetric AVA by MRI was less severe in LF/LG (0.54 ± 0.08 cm2/m2) and NF/LG (0.61 ± 0.08 cm2/m2) than in HG/LF (0.46 ± 0.07 cm2/m2, p < 0.05) AS. Also indexed mass was less in LF/LG (75 ± 12 g/m2) and LG/NF (81 ± 18 g/m2) than in HG/LF (100 ± 27 g/m2, p < 0.05) AS. All groups of AS had predominantly concentric hypertrophy remodeling, and similar amounts of focal fibrosis (1.6 ± 3.9%, 1.5҃ ± 2.2%, 0.8 ± 0.7% and 1.0 ± 1.3% for HG/NF HG/LF, LG/NF and LG/LF groups respectively p = NS) Conclusions: CMR confirmed that echocardiographic classification system of AS was overall accurate. Patients with paradoxical LG/LF and LG/NF AS had less severe AS severity, less hypertrophy and similar remodeling and similar amount of focal fibrosis than HG/LF AS.