Hypertrophic Cardiomyopathy Center, Policlinico di Monza, Monza, Italy.
Hypertrophic Cardiomyopathy Center, Policlinico di Monza, Monza, Italy.
J Am Coll Cardiol. 2020 Nov 10;76(19):2238-2247. doi: 10.1016/j.jacc.2020.09.534.
The mitral valve is often structurally abnormal in hypertrophic cardiomyopathy (HCM). However, the mechanisms responsible for these abnormalities remain controversial. In 2016 we identified, at myectomy, muscular mitral-aortic discontinuity in 5 young patients with obstructive HCM.
This study sought to confirm our preliminary findings and assess the prevalence of muscular mitral-aortic discontinuity in obstructive HCM.
At our center, from January 2017 to April 2018, the area between the anterior mitral leaflet and aortic valve was inspected at myectomy in 106 consecutive patients with HCM.
Muscular mitral-aortic discontinuity was identified in 28 (26%) patients and was significantly more common in younger than older patients (age 39 ± 13 years vs. 58 ± 11 years; p < 0.001). Muscular discontinuity was present in each of 6 patients aged <30 years but only 1 (2.7%) of 37 aged ≥60 years. Pathogenic sarcomere mutations were identified in 22 (79%) of 28 patients with and 24 (31%) of 78 without discontinuity (p < 0.001) and were associated with discontinuity independently of age (p = 0.021). Discontinuity mean length was 7.3 mm and was inversely related to age (p = 0.022). At echocardiography, the anterior mitral leaflet was longer in patients with than those without discontinuity (34 ± 4 mm vs. 29 ± 5 mm; p < 0.001).
We report, for the first time, muscular mitral-aortic discontinuity in HCM. At myectomy, a long muscular discontinuity displaced the anterior mitral leaflet toward the apex in most young patients, was significantly associated with sarcomere mutations independent of age, and was extremely uncommon in older patients. These findings suggest that a long muscular mitral-aortic discontinuity could predispose to the development of outflow obstruction in young patients with sarcomere mutations.
二尖瓣在肥厚型心肌病（HCM）中常存在结构异常。然而，导致这些异常的机制仍存在争议。2016 年，我们在 5 名梗阻性 HCM 年轻患者的心肌切除术时发现了肌性二尖瓣-主动脉不连续。
本研究旨在证实我们的初步发现，并评估梗阻性 HCM 中肌性二尖瓣-主动脉不连续的发生率。
在我们中心，2017 年 1 月至 2018 年 4 月，对 106 例连续 HCM 患者的心肌切除术进行了检查，检查前二尖瓣叶和主动脉瓣之间的区域。
在 28 例（26%）患者中发现了肌性二尖瓣-主动脉不连续，年轻患者比老年患者更为常见（年龄 39 ± 13 岁 vs. 58 ± 11 岁；p < 0.001）。6 例年龄<30 岁的患者均存在肌性不连续，而 37 例年龄≥60 岁的患者中仅 1 例（2.7%）存在肌性不连续。28 例肌性不连续患者中有 22 例（79%）存在致病性肌节突变，78 例无肌性不连续患者中有 24 例（31%）存在致病性肌节突变（p < 0.001），且肌性不连续与年龄无关（p = 0.021）。不连续的平均长度为 7.3mm，与年龄呈负相关（p = 0.022）。在超声心动图上，有不连续的患者的前二尖瓣叶比无不连续的患者长（34 ± 4mm vs. 29 ± 5mm；p < 0.001）。
我们首次报道了 HCM 中的肌性二尖瓣-主动脉不连续。在心肌切除术时，大多数年轻患者的长肌性不连续将前二尖瓣叶推向心尖，与肌节突变显著相关，且与年龄无关，在老年患者中极为罕见。这些发现表明，长的肌性二尖瓣-主动脉不连续可能使携带肌节突变的年轻患者更容易发生流出道梗阻。
