Peggy Nguyen, MD
Kim D, Shim CY, Hong G-R, Kim M-H, Seo J, Cho IJ, et al. Clinical Implications and Determinants of Left Atrial Mechanical Dysfunction in Patients With Stroke. Stroke. 2016
Cardiovascular evaluation is an important part of the evaluation of the stroke patient, in part due to its use to diagnose cardioembolic etiologies of stroke, but also to assess for risk of future events. Left atrial enlargement has been associated with recurrent and first episodes of stroke, even in cases where dysrhythmias are not present; however, the mechanism by which this occurs is not well understood. Here, the authors use TTE with speckle tracking imaging to (1) assess enlargement and impaired mechanical function of the left atrium to define the risk of cardioembolism in stroke patients and (2) define the major determinants of left atrial mechanical dysfunction in these patients.
Two hundred forty-eight patients, derived from a larger study population of 316 acute ischemic stroke patients, who were referred for TTE and TEE, were analyzed. All patients underwent routine TTE, a TEE, as well as 2D speckle tracking echocardiography of the left atrium. Left atrial function was defined by the global left atrial longitudinal strain (LALS) and patients were divided into four groups for analyses: Group 1 – small LA with preserved LALS, Group 2 – large LA with preserved LALS, Group 3 – small LA with impaired LALS, and Group 4 – large LA with impaired LALS. Patients with large LA but impaired function (LALS) were significantly older than the other groups and experienced higher frequency of embolic strokes.
The authors delve deep into the relationship between echo parameters of LA size and function. A global LALS less than 11.5% was found to be more predictive of a LA or LA appendage thrombus than LA volume index. Both global LALS and LA volume index were predictive of parameters which are suggestive of thrombus formation (and therefore, cardioembolic stroke risk), such as decreased LAA emptying velocity < 20 cm/s and complex aortic plaque. Left atrial function is independently correlated with age, LV function, LA volume index, and aortic stiffness.
The global LALS assessed using 2D speckle tracking imaging on TTE, being predictive of parameters suggestive of thrombus formation and being predictive of thrombus itself, provides an additional measurement which we can use to stratify patients, which can be of particular utility for patients who cannot tolerate a TEE. The presence of impaired global LALS may not be sufficient in of itself to warrant anticoagulation without further investigation, but it should prompt further studies, either the more invasive TEE or cardiac CT or MRI, which is not as widely available.