Meisel Karl, Yuan Kristy, Fang Qizhi, Bibby Dwight, Lee Randall, Schiller Nelson B
University of California, San Francisco, San Francisco, California.
University of Pennsylvania, Philadelphia, Pennsylvania.
J Stroke Cerebrovasc Dis. 2019 Jul;28(7):1891-1896. doi: 10.1016/j.jstrokecerebrovasdis.2019.04.004. Epub 2019 Apr 26.
Cryptogenic stroke, now defined as embolic stroke of undetermined source (ESUS), represents about a quarter of all ischemic strokes and the reoccurrence is high. Understanding this stroke subtype better would likely guide treatment recommendations. In this study, we tested the hypothesis that left atrial (LA) shape and function at rest, as well as with exercise, are abnormal compared to matched normal controls.
The study design was prospective enrollment of ESUS subjects who underwent measurement of LA function at rest and exercise by 2D and 3D echocardiograms. The exercise portion of the study was conducted using a ramped supine bicycle protocol during which LA function was measured. Stroke subjects were matched with normal subjects by age, gender, and body surface area.
Over a 1-year enrollment period, 18 ESUS patients met inclusionary criteria and were studied. Their average age was 58 years old and 44% were female. ESUS subjects have larger LA end-diastolic volume at rest (14 versus 11 mL/m, P = .04) and with exercise (11 versus 6 mL/m, P = .001) compared to normal controls. In ESUS, there was a lack of response to maximal exercise of LA function as measured by the LA ejection fraction (61% versus 73% P = .001) and the LA function index (.68 versus .82, P = .02). The 3D analysis showed spherical remodeling of the LA in ESUS. This remodeling was documented by the sphericity index, which was increased in both diastole (.40 versus .32, P = .02) and systole (.63 versus .71 P = .03).
In support of our hypothesis, we found that ESUS subjects have LA dysfunction and remodeling at rest and exercise in comparison to healthy, matched controls. Evaluation of the left atrium in this high-risk stroke subtype has potential to inform stroke prevention strategies and to suggest pathways for research.
隐源性卒中，现定义为不明来源栓塞性卒中（ESUS），约占所有缺血性卒中的四分之一，且复发率高。更好地了解这种卒中亚型可能会指导治疗建议。在本研究中，我们检验了这样一个假设：与匹配的正常对照组相比，静息及运动时左心房（LA）的形态和功能存在异常。
本研究设计为前瞻性纳入接受二维和三维超声心动图测量静息及运动时LA功能的ESUS受试者。研究的运动部分采用斜坡仰卧位自行车方案进行，在此期间测量LA功能。卒中受试者与正常受试者按年龄、性别和体表面积进行匹配。
在为期1年的入组期间，18例ESUS患者符合纳入标准并接受研究。他们的平均年龄为58岁，44%为女性。与正常对照组相比，ESUS受试者静息时（14 vs 11 mL/m，P = 0.04）及运动时（11 vs 6 mL/m，P = 0.001）的左房舒张末期容积更大。在ESUS中，通过左房射血分数（61% vs 73%，P = 0.001）和左房功能指数（0.68 vs 0.82，P = 0.02）测量，左房功能对最大运动缺乏反应。三维分析显示ESUS患者左房呈球形重塑。这种重塑通过球形指数得以记录，该指数在舒张期（0.40 vs 0.32，P = 0.02）和收缩期（0.63 vs 0.71，P = 0.03）均增加。
为支持我们的假设，我们发现与健康匹配的对照组相比，ESUS受试者在静息及运动时存在左房功能障碍和重塑。对这种高危卒中亚型的左心房进行评估有可能为卒中预防策略提供信息，并为研究指明方向。
