Cardiac Imaging Department.
Cardiomyopathy Unit, Instituto Cardiovascular de Buenos Aires, Buenos Aires, Argentina.
J Cardiovasc Med (Hagerstown). 2019 Jun;20(6):389-396. doi: 10.2459/JCM.0000000000000800.
Left ventricular outflow tract (LVOT) obstruction is a key feature of hypertrophic cardiomyopathy (HCM) that identifies patients at increased risk of adverse outcomes. Previous studies have hypothesized that LVOT obstruction enhances myocardial fibrosis and increases left ventricular (LV) filling pressures, producing greater clinical deterioration. However, this hypothesis has not been demonstrated in a clinical cohort comparing obstructive and nonobstructive patients.
Patients with HCM in whom Doppler echocardiography was performed within 30 days of cardiac MRI were enrolled, using the E/e' ratio to assess LV diastolic function and late gadolinium enhancement to evaluate the extent of fibrosis. Data were assorted according to LVOT obstruction status at rest.
The current study enrolled 67 patients who were mostly middle-aged (56.8 ± 13.2 years old) men (75%) with preserved ejection fraction. Obstructive HCM presented a significant association with a high fibrosis extent [odds ratio (OR) 3.33; P = 0.034] which was maintained after adjusting for sex and age (OR 4.37; P = 0.016) but not for maximum LV wall thickness (OR 2.13; P = 0.225). Obstructive HCM was also associated with a clinically significant E/e' ratio more than 14 (OR 7.8; P = 0.001) which decreased slightly after adjusting for age, sex and maximum LV thickness (OR 6.54; P = 0.014). There was a significant association between an E/e' ratio more than 14 and the extent of fibrosis (OR 1.29; P < 0.001) which was maintained after adjusting for age, sex and maximum LV wall thickness (OR 1.36; P = 0.001).
LVOT obstruction may play a role in the extent of fibrosis in HCM, possibly conditioning greater diastolic dysfunction.
左心室流出道（LVOT）梗阻是肥厚型心肌病（HCM）的一个关键特征，它可识别出发生不良预后风险增加的患者。先前的研究假设 LVOT 梗阻会增强心肌纤维化并增加左心室（LV）充盈压，从而导致更严重的临床恶化。然而，在比较梗阻性和非梗阻性患者的临床队列中，这一假设尚未得到证实。
研究纳入了在心脏 MRI 检查后 30 天内接受多普勒超声心动图检查的 HCM 患者，使用 E/e' 比值评估 LV 舒张功能，使用晚期钆增强评估纤维化程度。根据 LVOT 梗阻状态对数据进行分类。
本研究共纳入 67 名患者，大多数为中年男性（56.8±13.2 岁）（75%），射血分数正常。梗阻性 HCM 与较高的纤维化程度显著相关（比值比 [OR] 3.33；P=0.034），这种相关性在调整性别和年龄后仍然存在（OR 4.37；P=0.016），但与最大 LV 壁厚度无关（OR 2.13；P=0.225）。梗阻性 HCM 还与临床意义显著的 E/e' 比值大于 14 相关（OR 7.8；P=0.001），调整年龄、性别和最大 LV 厚度后略有下降（OR 6.54；P=0.014）。E/e' 比值大于 14 与纤维化程度之间存在显著相关性（OR 1.29；P<0.001），在调整年龄、性别和最大 LV 壁厚度后仍然存在（OR 1.36；P=0.001）。
LVOT 梗阻可能在 HCM 的纤维化程度中起作用，可能导致更大的舒张功能障碍。
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