Department of Cardiology, Mayo Clinic, 200 First Street, Gonda Building 6-402, Rochester, MN, USA.
Curr Cardiol Rep. 2020 Jul 9;22(9):78. doi: 10.1007/s11886-020-01341-x.
A significant proportion of patients with aortic stenosis (AS) have discordance in severity by mean gradient/peak velocity and aortic valve area. Low gradient aortic stenosis (LG-AS) is defined when the aortic valve area is < 1 cm consistent with severe AS and mean aortic gradient is < 40 mmHg consistent with non-severe AS. LG-AS represents a diagnostic and therapeutic challenge.
To summarize the different categories, diagnosis, management, and prognosis of LG-AS. LG-AS is classified as classical (ejection fraction (EF) < 50%, indexed stroke volume (SVi) < 35 ml/m), paradoxical (EF > 50%, SVi < 35 ml/m), pseudo-severe (moderate AS with reduced EF), or normal flow low gradient AS.
Recent findings emphasize the importance of low-dose dobutamine stress echocardiography and CT calcium score in the assessment of aortic valve. In addition, flow reserve (increase in SV > 50%) can be evaluated during dobutamine stress echocardiography and helps predict perioperative prognosis. Patients with LG-AS have better survival with aortic valve replacement (AVR) compared to medical therapy, irrespective of presence or absence of flow reserve. Some recent studies suggest that transcatheter aortic valve replacement (TAVR) may be superior to surgical AVR for patients with a lack of contractile flow reserve or those with paradoxical LG-AS, but further investigation is needed to clarify optimal treatment. The role of TAVR in patients with moderate AS and reduced EF is also under investigation.
相当一部分主动脉瓣狭窄（AS）患者的平均梯度/峰值速度和主动脉瓣面积的严重程度存在差异。当主动脉瓣面积<1cm²且符合严重 AS，平均主动脉梯度<40mmHg 且符合非严重 AS 时，定义为低梯度主动脉瓣狭窄（LG-AS）。LG-AS 是一个诊断和治疗上的挑战。
总结 LG-AS 的不同类别、诊断、治疗和预后。LG-AS 分为经典型（射血分数（EF）<50%，指数化每搏量（SVi）<35ml/m²）、矛盾型（EF>50%，SVi<35ml/m²）、假性严重型（中度 AS 伴 EF 降低）或正常流量低梯度 AS。
最近的研究结果强调了低剂量多巴酚丁胺负荷超声心动图和 CT 钙评分在评估主动脉瓣中的重要性。此外，在多巴酚丁胺负荷超声心动图中可以评估流量储备（SV 增加>50%），有助于预测围手术期预后。与药物治疗相比，LG-AS 患者行主动脉瓣置换术（AVR）的生存率更高，无论是否存在流量储备。一些最近的研究表明，对于缺乏收缩性流量储备或矛盾型 LG-AS 的患者，经导管主动脉瓣置换术（TAVR）可能优于手术 AVR，但需要进一步研究以明确最佳治疗方法。TAVR 在中度 AS 和 EF 降低的患者中的作用也在研究中。
