Background

Exercise intolerance is the most common symptom in hypertrophic cardiomyopathy (HCM). We examined whether inability to augment myocardial mechanics during exercise would influence functional performance and clinical outcomes in HCM.

Methods

Ninety-five HCM patients (32 nonobstructive, 32 labile-obstructive, 31 obstructive) and 26 controls of similar age and gender distribution were recruited prospectively. They underwent rest and treadmill stress strain echocardiography, and 61 of them underwent magnetic resonance imaging. Mechanical reserve (MRES) was defined as percent change in systolic strain rate (SR) immediately postexercise.

Results

Global strain and SR were significantly lower in HCM patients at rest (strain: nonobstructive, −15.6 ± 3.0; labile-obstructive, −15.9 ± 3.0; obstructive, −13.8 ± 2.9; control, −17.7% ± 2.1%, P < .001; SR: nonobstructive, −0.92 ± 0.20; labile−obstructive, −0.94 ± 0.17; obstructive, −0.85 ± 0.18; control, −1.04 ± 0.14 s⁻¹, P = .002); and immediately postexercise (strain: nonobstructive, −15.6 ± 3.0; labile-obstructive, −17.6 ± 3.6; obstructive, −15.6 ± 3.6; control, −19.2 ± 3.1%; P = .001; SR: nonobstructive, −1.41 ± 0.37; labile-obstructive, −1.64 ± 0.38; obstructive, −1.32 ± 0.29; control, −1.82 ± 0.29 s⁻¹, P < .001). MRES was lower in nonobstructive and obstructive compared with labile-obstructive and controls (51% ± 29%, 54% ± 31%, 78% ± 38%, 77% ± 30%, P = .001, respectively). Postexercise SR and MRES were associated with exercise capacity (r = 0.47 and 0.42, P < .001 both, respectively). When adjusted for age, gender, body mass index, E/e’, and resting peak instantaneous systolic gradient, postexercise SR best predicted exercise capacity (r = 0.74, P = .003). Postexercise SR was correlated with extent of late gadolinium enhancement (r = 0.34, P = .03). By Cox regression, exercise SR and MRES predicted ventricular tachycardia/ventricular fibrillation (VT/VF) even after adjustment for age, gender, family history of sudden cardiac death, septum ≥ 3 cm and abnormal blood pressure response (P = .04 and P = .046, respectively).

Conclusions

Nonobstructive and obstructive patients have reduced MRES compared with labile-obstructive and controls. Postexercise SR correlates with LGE and exercise capacity. Exercise SR and MRES predict VT/VF.

中文翻译：

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肥厚性心肌病的休息和压力纵向收缩期左心室力学：对预后的影响。

背景

运动不耐受是肥厚型心肌病（HCM）中最常见的症状。我们检查了运动过程中无法增强心肌力学是否会影响HCM的功能表现和临床结局。

方法

前瞻性招募了95名HCM患者（32名无梗阻，32例不稳定梗阻，31例梗阻）和26名年龄和性别分布相似的对照。他们进行了休息和跑步机应力应变超声心动图检查，其中61人进行了磁共振成像。机械储备（MRES）定义为运动后立即收缩收缩率（SR）的变化百分比。

结果

HCM患者静息时的总应变和SR显着降低（应变：非阻塞性，-15.6±3.0;不稳定阻塞性，-15.9±3.0;阻塞性，-13.8±2.9;对照，-17.7％±2.1％，P  <。 001； SR：非阻塞性，-0.92±0.20；不稳定-阻塞性，-0.94±0.17；阻塞性，-0.85±0.18；对照，-1.04±0.14 s ^-1，P  ＝ .002）；并立即进行运动后锻炼（应变：无阻塞，-15.6±3.0;不稳定阻塞，-17.6±3.6;阻塞，-15.6±3.6;对照，-19.2±3.1％; P  = .001; SR：无阻塞，-1.41±0.37 ;不稳定梗阻，-1.64±0.38;梗阻，-1.32±0.29;对照，-1.82±0.29 s ^-1，P <.001）。与不稳定梗阻组和对照组相比，MRES在非梗阻组和梗阻组中较低（分别为51％±29％，54％±31％，78％±38％，77％±30％，P  = .001）。运动后的SR和MRES与运动能力有关（r分别 为0.47和0.42，P  <0.001）。在对年龄，性别，体重指数，E / e'和静止峰值瞬时收缩压梯度进行调整后，运动后SR可以最佳预测运动能力（r  = 0.74，P  = 0.003）。运动后SR与晚期g增强程度相关（r  = 0.34，P = .03）。通过Cox回归，即使在调整了年龄，性别，心脏性猝死家族史，间隔≥3 cm和血压异常反应后，运动SR和MRES仍可预测室性心动过速/室颤（VT / VF）（P  = .04和P 分别为.046）。

结论

非阻塞性和阻塞性患者与不稳定阻塞性和对照组相比，MRES降低。运动后SR与LGE和运动能力有关。锻炼SR和MRES可以预测VT / VF。