Kizilbash A M, Heinle S K, Grayburn P A
Department of Internal Medicine, University of Texas Southwestern Medical School and VA Medical Center, Dallas 75235-9047, USA.
Circulation. 1998 Feb 10;97(5):461-6. doi: 10.1161/01.cir.97.5.461.
Improvement in the left ventricular outflow tract (LVOT) gradient has been used as a means of assessing response to therapy in patients with hypertrophic obstructive cardiomyopathy (HOCM). To our knowledge, no data exist regarding the spontaneous day-to-day variability of the LVOT gradient in patients with HOCM. Defining the magnitude of such variability is critical to properly understand how much improvement in LVOT gradient must be present to invoke a therapeutic response.
We studied the spontaneous variation in the continuous-wave, Doppler-derived pressure gradient on 5 consecutive days in 12 HOCM patients and 5 aortic stenosis control subjects. While in some patients the day-to-day variability in resting gradient was small, in others it varied markedly. The 95% confidence interval for attributing a change in LVOT gradient to factors other than random variation is +/-32 mm Hg for resting gradient and +/-50 mm Hg for provoked gradient. The mean coefficient of variation for gradient across 5 days for the group was 0.52+/-0.33 for resting gradient and 0.46+/-0.16 for provoked gradient. The day-to-day variability in pressure gradient could not be explained by changes in heart rate, blood pressure, or left ventricular end-diastolic dimension, each of which had a coefficient of variation <.11. Moreover, technical factors related to the performance or interpretation of the studies did not account for it because the coefficient of variation for gradient in aortic stenosis was <10% and interobserver and intraobserver agreement was excellent (r=.96 and .98, respectively).
The LVOT pressure gradient varies considerably from day to day in stable patients with HOCM. A single measurement of pressure gradient is not adequate to define the severity of dynamic LVOT obstruction in HOCM.
左心室流出道（LVOT）梯度的改善已被用作评估肥厚性梗阻性心肌病（HOCM）患者治疗反应的一种手段。据我们所知，尚无关于HOCM患者LVOT梯度日常自发变异性的数据。确定这种变异性的大小对于正确理解LVOT梯度必须有多大改善才能引发治疗反应至关重要。
我们对12例HOCM患者和5例主动脉瓣狭窄对照受试者连续5天的连续波多普勒衍生压力梯度的自发变化进行了研究。虽然在一些患者中静息梯度的日常变异性较小，但在其他患者中变化明显。将LVOT梯度变化归因于随机变异以外因素的95%置信区间，静息梯度为±32 mmHg，激发梯度为±50 mmHg。该组5天内梯度的平均变异系数，静息梯度为0.52±0.33，激发梯度为0.46±0.16。压力梯度的日常变异性无法用心率、血压或左心室舒张末期内径的变化来解释，其中每一项的变异系数均<0.11。此外，与研究的实施或解释相关的技术因素也不能解释这种变异性，因为主动脉瓣狭窄时梯度的变异系数<10%，观察者间和观察者内一致性极佳（分别为r = 0.96和0.98）。
在病情稳定的HOCM患者中，LVOT压力梯度每天变化很大。单次测量压力梯度不足以确定HOCM中动态LVOT梗阻的严重程度。
