Background

Cardioembolic stroke is a major source of mortality and disability worldwide. The authors hypothesized that quantitative characterization of intracardiac blood stasis may be useful to determine cardioembolic risk in order to personalize anticoagulation therapy. The aim of this study was to assess the relationship between image-based metrics of blood stasis in the left ventricle and brain microembolism, a surrogate marker of cardiac embolism, in a controlled animal experimental model of acute myocardial infarction (AMI).

Methods

Intraventricular blood stasis maps were derived from conventional color Doppler echocardiography in 10 pigs during anterior AMI induced by sequential ligation of the mid and proximal left anterior descending coronary artery (AMI-1 and AMI-2 phases). From these maps, indices of global and local blood stasis were calculated, such as the average residence time and the size and ratio of contact with the endocardium of blood regions with long residence times. The incidence of brain microemboli (high-intensity transient signals [HITS]) was monitored using carotid Doppler ultrasound.

Results

HITS were detected in 0%, 50%, and 90% of the animals at baseline and during AMI-1 and AMI-2 phases, respectively. The average residence time of blood in the left ventricle increased in parallel. The residence time performed well to predict microemboli (C-index = 0.89, 95% CI, 0.75–1.00) and closely correlated with the number of HITS (R = 0.87, P < .001). Multivariate and mediation analyses demonstrated that the number of HITS during AMI phases was best explained by stasis. Among conventional echocardiographic variables, only apical wall motion score weakly correlated with the number of HITS (R = 0.3, P = .04). Mural thrombosis in the left ventricle was ruled out in all animals.

Conclusions

The degree of stasis of blood in the left ventricle caused by AMI is closely related to the incidence of brain microembolism. Therefore, stasis imaging is a promising tool for a patient-specific assessment of cardioembolic risk.

中文翻译：

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血瘀成像预测急性心肌梗死期间的脑微栓塞

背景

心源性卒中是全世界死亡和残疾的主要来源。作者假设，心内血瘀的定量特征可能有助于确定心源性栓塞风险，以便个性化抗凝治疗。本研究的目的是在急性心肌梗死 (AMI) 的受控动物实验模型中评估基于图像的左心室血瘀指标与脑微栓塞（心脏栓塞的替代标志物）之间的关系。

方法

脑室内血瘀图来自 10 头猪的常规彩色多普勒超声心动图，该图在前部 AMI 期间由左前降支中段和近端顺序结扎（AMI-1 和 AMI-2 期）引起。从这些地图中，计算了全局和局部血瘀的指标，例如平均停留时间以及停留时间长的血液区域与心内膜接触的大小和比例。使用颈动脉多普勒超声监测脑微栓子（高强度瞬态信号 [HITS]）的发生率。

结果

在基线和 AMI-1 和 AMI-2 阶段，分别在 0%、50% 和 90% 的动物中检测到 HITS。血液在左心室的平均停留时间平行增加。停留时间在预测微栓子方面表现良好（C 指数 = 0.89，95% CI，0.75–1.00）并且与 HITS 的数量密切相关（R  = 0.87，P  < .001）。多变量和中介分析表明，AMI 阶段 HITS 的数量最好用停滞来解释。在传统的超声心动图变量中，只有心尖壁运动评分与 HITS 的数量呈弱相关（R  = 0.3，P  = .04）。所有动物均排除左心室壁血栓形成。

结论

AMI引起的左心室血瘀程度与脑微栓塞的发生密切相关。因此，淤滞成像是一种有前途的工具，可用于患者特定的心源性栓塞风险评估。