Department of Medicine, Québec Heart & Lung Institute, Laval University, Québec City, Québec, Canada.
Curr Opin Cardiol. 2013 Sep;28(5):524-30. doi: 10.1097/HCO.0b013e32836245e0.
The occurrence of low-flow low-gradient severe aortic stenosis in patients with normal left ventricle (LV) ejection fraction has only been recently described. The purpose of this review is to highlight the diagnostic and management specificities of this entity.
In the American College of Cardiology/American Heart Association guidelines, the criteria for severe aortic stenosis are an effective orifice area less than1.0 cm or less than 0.6 cm/m, a transvalvular mean gradient greater than 40 mmHg and a peak aortic jet velocity greater than 4.0 m/s. The guidelines also acknowledge that lower gradients may be observed in patients with depressed ejection fraction, with the implication that such an occurrence is not expected in patients with normal ejection fraction. However, recent studies confirm that a bona fide low-flow, low-gradient (LFLG) state may nonetheless be observed in 10-25% of patients with severe aortic stenosis and normal left ventricular ejection fraction (LVEF). This entity bears analogy with normal LVEF heart failure and is due to a restrictive physiology in relation with more pronounced LV concentric remodeling, a smaller LV cavity size and reductions in LV compliance and filling.
The clinical relevance of LFLG severe aortic stenosis is now recognized in the most recent European (European Society of Cardiology/European Association for Cardio-Thoracic Surgery) guidelines, which also emphasize that it should be confirmed as being due to low-flow conditions. In particular, patients with bona fide paradoxical LFLG aortic stenosis should be distinguished from patients with normal flow and low gradient because of inconsistent cutoff criteria because, among patients with severe aortic stenosis, the former have the worst prognosis, whereas the latter have the best.
最近才描述了左心室射血分数正常的患者出现低流量低梯度严重主动脉瓣狭窄的情况。本文的目的是强调这种疾病的诊断和管理特点。
在美国心脏病学会/美国心脏协会指南中，严重主动脉瓣狭窄的标准为有效瓣口面积<1.0cm或<0.6cm/m，跨瓣平均梯度>40mmHg，峰值主动脉射流速度>4.0m/s。该指南还承认，射血分数降低的患者可能会出现较低的梯度，这意味着在射血分数正常的患者中不应出现这种情况。然而，最近的研究证实，10-25%的严重主动脉瓣狭窄和正常左心室射血分数（LVEF）患者仍可能出现真正的低流量、低梯度（LFLG）状态。这种情况与正常射血分数心力衰竭类似，是由于与更明显的左心室向心性重构、左心室腔缩小以及左心室顺应性和充盈减少相关的限制性生理所致。
最近的欧洲（欧洲心脏病学会/欧洲心胸外科学会）指南也认识到 LFLG 严重主动脉瓣狭窄的临床相关性，并强调应确认其是否由于低流量所致。特别是，应区分真正的矛盾性 LFLG 主动脉瓣狭窄患者与正常流量和低梯度患者，因为不一致的截断标准，因为在严重主动脉瓣狭窄患者中，前者预后最差，而后者预后最好。
