Background— The clinical relevance and management of paradoxical low-flow, low-gradient aortic stenosis (LFLG-AS) with preserved left ventricular ejection fraction remain debated. The aim of this study is to determine the features and outcome of LFLG-AS assessed using cardiac catheterization. Methods and Results— Between 2000 and 2010, 768 patients with preserved left ventricular ejection fraction (>50%) and severe AS (valve area ≤1cm 2 ) without other valvular disease underwent cardiac catheterization. Mean age was 74±8 years, 42% were women, and 46% had associated coronary artery disease. The prevalence of LFLG (indexed left ventricular stroke volume <35 mL/m 2 and mean gradient <40 mm Hg), normal flow high gradient, normal flow low gradient, and low flow high gradient were 13%, 50%, 22%, and 15%, respectively. Compared with patients with normal flow high gradient, those with LFLG were significantly older, with significantly reduced systemic arterial compliance and vascular resistances and increased valvulo-arterial impedance (all P <0.05). Ten-year survival was reduced in LFLG-AS (32±9%) compared with normal flow high gradient (66±4%; P =0.0002). After adjustment for other risk factors, LFLG-AS was independently associated with reduced long-term survival (hazard ratio, 1.85; 95% confidence interval, 1.08–3.07; P =0.02). However, despite higher operative mortality, patients with LFLG-AS undergoing aortic valve replacement seemed to have better long-term survival than those managed conservatively (5-year survival rate: 63±6% versus 38±15%; P =0.007; hazard ratio, 0.23; 95% confidence interval, 0.09–0.59; P =0.002). Conclusions— This large cardiac catheterization–based study reports that the LFLG-AS entity is not rare and is associated with worse outcome whether treated medically or surgically. However, these patients may have better long-term survival if treated surgically. Further prospective studies are needed to confirm this finding.

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