Cardiology Department, Menoufiya University, Shebin, Egypt; The BAHCM National Program, Alexandria, Egypt; Aswan Heart Center, Aswan, Egypt.
J Am Soc Echocardiogr. 2013 Dec;26(12):1397-406. doi: 10.1016/j.echo.2013.08.026. Epub 2013 Oct 3.
Although patients with hypertrophic cardiomyopathy (HCM) have normal ejection fractions at rest, the investigators hypothesized that these patients have differentially abnormal systolic function reserves, limiting their exercise capacity compared with patients with hypertension (HTN).
Forty patients with HCM (mean age, 39.1 ± 12 years), 20 patients with HTN with LVH, and 33 healthy individuals underwent resting and peak exercise echocardiography using two-dimensional strain imaging. Peak longitudinal systolic strain (εsys) and strain rate were measured in apical views. Circumferential εsys and left ventricular (LV) twist were analyzed from short-axis views. LV systolic dyssynchrony was measured from regional longitudinal strain curves as the standard deviation of time to peak strain (time from the beginning of the Q wave on electrocardiography to peak εsys) between 12 segments. The differences between resting and peak exercise values were analyzed, and functional reserve was calculated as the difference divided by the resting value.
In patients with HCM, resting values for longitudinal εsys, systolic strain rate, early diastolic strain rate, and atrial diastolic strain rate were significantly lower, while circumferential εsys and twist were higher, compared with patients with HTN and controls (P < .0001). Functional systolic reserve increased during exercise in controls (17 ± 6%), increased to a lesser extent in patients with HTN (10 ± 16%), and was markedly attenuated in patients with HCM (-23 ± 28%) (P < .001). At peak exercise, even with augmented circumferential εsys and twist in patients with HCM (P < .01) compared with those with HTN, both remained lower than in controls (P < .001). LV dyssynchrony was amplified during exercise in patients with HCM compared with those with HTN (P < .001). Within the entire population, exercise capacity was clearly correlated with systolic functional reserve. However when taken separately, it was mainly related to resting LV dyssynchrony and diastolic function in patients with HCM, whereas it was linked to age and LV wall thickness in those with HTN.
Patients with HCM have significantly limited systolic function reserve and more dynamic dyssynchrony with exercise compared with those with HTN. Two-dimensional strain imaging during stress may provide a new and reliable method to identify patients at higher cardiovascular risk.
尽管肥厚型心肌病（HCM）患者在静息时射血分数正常，但研究人员假设这些患者的收缩功能储备存在差异异常，限制了他们的运动能力，与高血压（HTN）患者相比。
40 名 HCM 患者（平均年龄 39.1 ± 12 岁）、20 名 HTN 合并 LVH 患者和 33 名健康个体接受二维应变成像的静息和峰值运动超声心动图检查。在心尖视图中测量峰值纵向收缩应变（εsys）和应变率。从短轴视图分析圆周εsys 和左心室（LV）扭转。LV 收缩不同步通过 12 个节段的峰值应变时间的标准差（从心电图 Q 波开始到峰值εsys 的时间）从区域纵向应变曲线进行测量。分析了静息值和峰值运动值之间的差异，并将功能储备计算为差异除以静息值。
与 HTN 患者和对照组相比，HCM 患者的纵向εsys、收缩期应变率、早期舒张期应变率和心房舒张期应变率在静息时显著降低，而圆周εsys 和扭转较高（P <.0001）。对照组在运动过程中收缩功能储备增加（17 ± 6%），HTN 患者增加幅度较小（10 ± 16%），HCM 患者明显减弱（-23 ± 28%）（P <.001）。在峰值运动时，即使 HCM 患者的圆周εsys 和扭转增加（P <.01）与 HTN 患者相比，两者仍低于对照组（P <.001）。与 HTN 患者相比，HCM 患者的 LV 不同步在运动过程中明显放大（P <.001）。在整个人群中，运动能力与收缩功能储备明显相关。然而，当单独考虑时，它主要与 HCM 患者的静息 LV 不同步和舒张功能有关，而与 HTN 患者的年龄和 LV 壁厚度有关。
与 HTN 患者相比，HCM 患者的收缩功能储备明显受限，运动时动态不同步更为明显。应激时的二维应变成像可能为识别心血管风险较高的患者提供一种新的可靠方法。
