Key result
Cardiac magnetic resonance showed low-gradient/low-flow aortic stenosis has a larger aortic valve area (0.54 vs 0.46 cm2/m2; P<0.05) and less LV hypertrophy than high-gradient/low-flow AS.
Why the study?
Does cardiac magnetic resonance imaging reveal differences in left ventricular remodeling and fibrosis among different hemodynamic types of severe aortic stenosis compared to echocardiography?
Observational (n=128)
Does cardiac magnetic resonance imaging reveal differences in left ventricular remodeling and fibrosis among different hemodynamic types of severe aortic stenosis compared to echocardiography?
Absolute Event Rate: 0.54% vs 0.46%
p-value: p=<0.05
CMR demonstrates that low-gradient/low-flow aortic stenosis has larger aortic valve areas and less left ventricular hypertrophy compared to high-gradient/low-flow AS, challenging the concept that LG/LF AS represents a more advanced disease state.
Questions whether low-gradient/low-flow AS represents advanced disease; hypothesis-generating for CMR phenotyping.
Background— Recent works using echocardiography suggested that low gradient (LG), low flow (LF) aortic stenosis (AS) has more pronounced left ventricular (LV) concentric remodeling, smaller LV cavity size, and more interstitial fibrosis compared with high gradient (HG) normal flow (NF) AS. Therefore, we evaluated the accuracy of echocardiographic measurements and compared remodeling and fibrosis in different types of AS by cardiac magnetic resonance (CMR). Methods and Results— A total of 128 patients (73±11 years of age; 75 men) with aortic valve area (AVA) <0.6 cm 2 /m 2 and ejection fraction >50% by echocardiography underwent CMR to measure planimetric AVA, phase-contrast indexed stroke volume, LV mass, and focal fibrosis. Using <40 mm Hg and indexed stroke volume <35 mL/m 2 by echocardiography as criteria for LG and LF, 69 (54%) patients were HG/NF, 28 (22%) HG/LF, 17 (13%) LG/NF, and 14 (11%) LG/LF AS. LV outflow tract area, indexed stroke volume, and AVA correlated well between echocardiography and CMR ( r =0.7, 0.61, and 0.65, respectively; P <0.001 for all). By CMR, however, planimetric AVA was larger in LF/LG (0.54±0.08 cm 2 /m 2 ) and LG/NF (0.61±0.08 cm 2 /m 2 ) than in HG/LF (0.46±0.07 cm 2 /m 2 ; P <0.05) AS, and indexed LV mass was lower in LG/LF (75±12 g/m 2 ) and LG/NF (81±18 g/m 2 ) than in HG/LF (100±27 g/m 2 ; P <0.05) AS. All groups of AS had similar LV volumes, predominantly concentric hypertrophy remodeling, and similar amounts of focal fibrosis. Conclusions— CMR confirmed overall accuracy of echocardiographic classification of AS but demonstrated that LG/LF and LG/NF AS have larger AVA, less LV hypertrophy, and similar focal fibrosis compared with HG/LF AS. This challenges the view that LG/LF AS is a more advanced state of AS.
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Barone‐Rochette et al. (2013) conducted an observational in Aortic stenosis (n=128). Cardiac magnetic resonance imaging vs. High-gradient/low-flow aortic stenosis was evaluated on Planimetric aortic valve area (cm2/m2) assessed by CMR in low-gradient/low-flow vs high-gradient/low-flow AS (p=<0.05). Cardiac magnetic resonance showed low-gradient/low-flow aortic stenosis has a larger aortic valve area (0.54 vs 0.46 cm2/m2; P<0.05) and less LV hypertrophy than high-gradient/low-flow AS.
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