Division of Cardiology, Department of Internal Medicine, Baylor University Medical Center, Dallas, Texas.
Division of Cardiology, Department of Internal Medicine, Baylor University Medical Center, Dallas, Texas.
JACC Cardiovasc Imaging. 2019 Feb;12(2):353-362. doi: 10.1016/j.jcmg.2018.11.006. Epub 2018 Dec 12.
Traditional approaches to the characterization of secondary or functional mitral regurgitation (MR) have largely ignored the critical importance of the left ventricle (LV). We propose that patients with secondary MR represent a heterogenous group, which can be usefully subdivided based on understanding that the effective regurgitant orifice area (EROA) is dependent on left ventricular end-diastolic volume (LVEDV). According to the Gorlin hydraulic orifice equation, patients with heart failure, an LV ejection fraction of 30%, an LVEDV of 220 to 250 ml, and a regurgitant fraction of 50% would be expected to have an EROA of ≈0.3 cm independent of specific tethering abnormalities of the mitral valve leaflets. The MR in these patients is proportionate to the degree of LV dilatation and can respond to drugs and devices that reduce LVEDV. In contrast, patients with EROA of 0.3 to 0.4 cm but with LVEDV of only 160 to 200 ml exhibit degrees of MR that are disproportionately higher than predicted by LVEDV. These patients appear to preferentially benefit from interventions directed at the mitral valve. Our proposed conceptual framework explains the apparently discordant results from 2 recent randomized controlled trials of mitral valve repair. The MITRA-FR (Percutaneous Repair with the MitraClip Device for Severe Functional/Secondary Mitral Regurgitation) trial enrolled patients who had MR that was proportionate to the degree of LV dilatation, and during long-term follow-up, the LVEDV and clinical outcomes of these patients did not differ from medically-treated control subjects. In comparison, the patients enrolled in the COAPT (Cardiovascular Outcomes Assessment of the MitraClip Percutaneous Therapy for Heart Failure Patients with Functional Mitral Regurgitation) trial had an EROA ≈30% higher but LV volumes that were ≈30% smaller, indicative of disproportionate MR. In these patients, transcatheter mitral valve repair reduced the risk of death and hospitalization for heart failure, and these benefits were paralleled by a meaningful decrease in LVEDV. Thus, characterization of MR as proportionate or disproportionate to LVEDV appears to be critical to the selection of an optimal treatment for patients with chronic heart failure and systolic dysfunction.
传统的继发性或功能性二尖瓣反流（MR）的特征描述方法在很大程度上忽略了左心室（LV）的关键重要性。我们提出，继发性 MR 患者代表一个异质群体，可以根据有效反流口面积（EROA）取决于左心室舒张末期容积（LVEDV）的理解，将其进行有用的细分。根据 Gorlin 水力口方程，心力衰竭患者、LV 射血分数为 30%、LVEDV 为 220 至 250ml 和反流分数为 50%的患者预计会有一个 ≈0.3cm 的 EROA，而与二尖瓣瓣叶的特定牵拉力异常无关。这些患者的 MR 与 LV 扩张的程度成正比，可以对降低 LVEDV 的药物和设备做出反应。相比之下，EROA 为 0.3 至 0.4cm 但 LVEDV 仅为 160 至 200ml 的患者表现出的 MR 程度高于 LVEDV 预测的不成比例。这些患者似乎优先受益于针对二尖瓣的干预措施。我们提出的概念框架解释了最近两项二尖瓣修复随机对照试验中明显不一致的结果。MITRA-FR（经皮 MitraClip 装置修复严重功能性/继发性二尖瓣反流）试验招募了 MR 与 LV 扩张程度成比例的患者，在长期随访中，这些患者的 LVEDV 和临床结局与接受药物治疗的对照组没有差异。相比之下，COAPT（心力衰竭伴功能性二尖瓣反流患者经皮 MitraClip 治疗的心血管结局评估）试验招募的患者的 EROA 约高 30%，但 LV 容积约小 30%，表明 MR 不成比例。在这些患者中，经导管二尖瓣修复降低了死亡和因心力衰竭住院的风险，这些益处与 LVEDV 的显著下降相平行。因此，将 MR 描述为与 LVEDV 成比例或不成比例似乎对选择慢性心力衰竭和收缩功能障碍患者的最佳治疗方法至关重要。
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