Hachicha Zeineb, Dumesnil Jean G, Bogaty Peter, Pibarot Philippe
Laval Hospital Research Center/Quebec Heart Institute, Department of Medicine, Laval University, Quebec, Canada.
Circulation. 2007 Jun 5;115(22):2856-64. doi: 10.1161/CIRCULATIONAHA.106.668681. Epub 2007 May 28.
Recent studies and current clinical observations suggest that some patients with severe aortic stenosis on the basis of aortic valve area may paradoxically have a relatively low gradient despite the presence of a preserved left ventricular (LV) ejection fraction. The objective of the present study was to document the prevalence, potential mechanisms, and clinical relevance of this phenomenon.
We retrospectively studied the clinical and Doppler echocardiographic data of 512 consecutive patients with severe aortic stenosis (indexed aortic valve area < or = 0.6 cm2 x m(-2)) and preserved LV ejection fraction (> or = 50%). Of these patients, 331 (65%) had normal LV flow output defined as a stroke volume index > 35 mL x m2, and 181 (35%) had paradoxically low-flow output defined as stroke volume index < or = 35 mL x m(-2). When compared with normal flow patients, low-flow patients had a higher prevalence of female gender (P<0.05), a lower transvalvular gradient (32+/-17 versus 40+/-15 mm Hg; P<0.001), a lower LV diastolic volume index (52+/-12 versus 59+/-13 mL x m(-2); P<0.001), lower LV ejection fraction (62+/-8% versus 68+/-7%; P<0.001), a higher level of LV global afterload reflected by a higher valvulo-arterial impedance (5.3+/-1.3 versus 4.1+/-0.7 mm Hg x mL(-1) x m(-2); P<0.001) and a lower overall 3-year survival (76% versus 86%; P=0.006). Only age (hazard ratio, 1.04; 95% CI, 1.01 to 1.08; P=0.025), valvulo-arterial impedance > 5.5 mm Hg x mL(-1) x m(-2) (hazard ratio, 2.6; 95% CI, 1.2 to 5.7; P=0.017), and medical treatment (hazard ratio, 3.3; 95% CI, 1.8 to 6.7; P=0.0003) were independently associated with increased mortality.
Patients with severe aortic stenosis may have low transvalvular flow and low gradients despite normal LV ejection fraction. A comprehensive evaluation shows that this pattern is in fact consistent with a more advanced stage of the disease and has a poorer prognosis. Such findings are clinically relevant because this condition may often be misdiagnosed, which leads to a neglect and/or an underestimation of symptoms and an inappropriate delay of aortic valve replacement surgery.
近期研究及当前临床观察表明，部分基于主动脉瓣面积诊断为重度主动脉瓣狭窄的患者，尽管左心室（LV）射血分数正常，但跨瓣压差可能反而相对较低。本研究的目的是记录这一现象的发生率、潜在机制及临床相关性。
我们回顾性研究了512例连续的重度主动脉瓣狭窄（主动脉瓣面积指数≤0.6 cm²×m⁻²）且左心室射血分数正常（≥50%）患者的临床及多普勒超声心动图数据。这些患者中，331例（65%）左心室血流输出正常，定义为每搏量指数＞35 mL×m²，181例（35%）跨瓣血流输出反常降低，定义为每搏量指数≤35 mL×m⁻²。与血流正常的患者相比，低血流患者女性比例更高（P＜0.05），跨瓣压差更低（32±17 vs 40±15 mmHg；P＜0.001），左心室舒张末期容积指数更低（52±12 vs 59±13 mL×m⁻²；P＜0.001），左心室射血分数更低（62±8% vs 68±7%；P＜0.001），反映左心室整体后负荷的瓣膜 - 动脉阻抗更高（5.3±1.3 vs 4.1±0.7 mmHg×mL⁻¹×m⁻²；P＜0.001），总体3年生存率更低（76% vs 86%；P = 0.006）。仅年龄（风险比，1.04；95%可信区间，1.01至1.08；P = 0.025）、瓣膜 - 动脉阻抗＞5.5 mmHg×mL⁻¹×m⁻²（风险比，2.6；95%可信区间，1.2至5.7；P = 0.017）及药物治疗（风险比，3.3；95%可信区间，1.8至6.7；P = 0.0003）与死亡率增加独立相关。
重度主动脉瓣狭窄患者尽管左心室射血分数正常，但可能存在跨瓣血流降低及压差降低。综合评估显示，这种模式实际上与疾病的更晚期阶段相符，预后更差。这些发现具有临床相关性，因为这种情况常可能被误诊，导致对症状的忽视和/或低估，以及主动脉瓣置换手术的不适当延迟。
