BACKGROUND The use of oversizing in mitral valve-in-valve (MViV) procedures can lead to non-uniform expansion of transcatheter heart valves (THV). This may have implications for THV durability. AIMS The objective of this study was to assess the extent and predictors of THV deformation in MViV procedures. METHODS We examined 33 patients who underwent MViV with SAPIEN prostheses. The extent of THV deformation (deformation index, eccentricity, neosinus volume, asymmetric leaflet expansion and vertical deformation) and hypoattenuating leaflet thickening (HALT) were assessed using cardiac computed tomography (CT), performed prospectively at 30 days post-procedure. For descriptive purposes, the THV deformation index was calculated, with values >1.00 representing a more hourglass shape. RESULTS Non-uniform underexpansion of THV was common after MViV implantation, with a median expansion area of 74.0% (interquartile range 68.1-84.1) at the narrowest level and a THV deformation index of 1.21 (1.13-1.29), but circularity was maintained with eccentricity ranging from 0.24 to 0.28.The degree of oversizing was a key factor associated with greater underexpansion and a higher deformation index (β=-0.634; p<0.001; β=0.594; p<0.001, respectively). Overall, the incidence of HALT on the 30-day postprocedural CT was 27.3% (9 of 33). Most patients (32 of 33) were on anticoagulation therapy, but the prothrombin time and international normalised ratio (PT-INR) at the time of the CT scan was <2.5 in 23 of 32 patients. Among patients with a PT-INR of <2.5, HALT was predominantly observed with a high THV deformation index of ≥1.18. CONCLUSIONS THV deformation, i.e., underexpansion and an hourglass shape, commonly occurs after MViV implantation and is negatively affected by excessive oversizing. Optimising THV expansion during MViV could potentially prevent HALT.

中文翻译：

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二尖瓣中瓣经导管心脏瓣膜的变形。

背景技术在二尖瓣中瓣(MViV)手术中使用过大的尺寸可能导致经导管心脏瓣膜(THV)的不均匀扩张。这可能会对 THV 耐久性产生影响。目的 本研究的目的是评估 MViV 手术中 THV 变形的程度和预测因素。方法 我们检查了 33 名接受 SAPIEN 假体 MViV 治疗的患者。使用心脏计算机断层扫描 (CT) 评估 THV 变形程度（变形指数、偏心率、新窦体积、不对称小叶扩张和垂直变形）和低衰减小叶增厚 (HALT)，并在术后 30 天前瞻性进行。出于描述目的，计算了 THV 变形指数，值 >1.00 表示更沙漏形状。结果 MViV 植入后 THV 不均匀扩张不足很常见，最窄水平处的中位扩张面积为 74.0%（四分位距 68.1-84.1），THV 变形指数为 1.21（1.13-1.29），但圆形度保持不变偏心率范围为0.24至0.28。尺寸过大的程度是与更大的膨胀不足和更高的变形指数相关的关键因素（分别为β=-0.634；p<0.001；β=0.594；p<0.001）。总体而言，术后 30 天 CT 中 HALT 的发生率为 27.3%（33 例中有 9 例）。大多数患者（33 名患者中的 32 名）正在接受抗凝治疗，但 32 名患者中有 23 名患者在 CT 扫描时的凝血酶原时间和国际标准化比值 (PT-INR) <2.5。在 PT-INR <2.5 的患者中，主要观察到 HALT 的 THV 变形指数≥1.18。结论 THV 变形，即扩张不足和沙漏形状，通常发生在 MViV 植入后，并且会受到尺寸过大的负面影响。在 MViV 期间优化 THV 扩展可能会阻止 HALT。