Left atrial strain and left atrial strain rate independently associated with risk of ischemic stroke in older adults

1. Patients who developed ischemic stroke were more likely to have reduced positive longitudinal left atrial strain than those who did not.

2. Reduced left atrial strain and positive left atrial strain rate were independently associated with ischemic stroke risk in patients with normal left atrial size.

Level of Evidence Rating: 2 (Good)

Study Rundown: Stroke is a common cause of morbidity and mortality in older adults, with the incidence expected to rise as the population ages. A recent study demonstrated that left atrial structure and dynamics may play a role in determining cardiovascular risk, including outcomes such as stroke. Left atrial strain (LAe) and left atrial strain rate (LASR) are two parameters that may be assessed using speckle-tracking echocardiography and used to prognosticate stroke risk. The present study sought to evaluate the relationship between LAe, LASR and ischemic stroke risk in older adults.

806 patients provided data regarding cardiovascular parameters and stroke risk. The mean positive LAe was 28.0% and the mean positive longitudinal LASR during ventricular systole was 0.94/second. 90 individuals suffered a silent cerebral infarct (11.2%) and 53 (6.6%) had an ischemic stroke. The following factors were independently associated with increased risk of ischemic stroke on univariable analysis: age, left ventricular (LV) ejection fraction, LV mass index, β-blocker use, left atrial (LA) minimum volume index, LA emptying volume index, abnormal LV global longitudinal strain, and incident atrial fibrillation.  Patients with ischemic stroke had significantly lower mean LAe, positive LASR during systole, negative LASR during diastole and during atrial contraction.

This study by Mannina et al concluded that left atrial function is associated with the risk of ischemic stroke in older adult patients and that relevant parameters can be accurately monitored with speckle-tracking echocardiography. This work is useful in understanding the relationship between cardiovascular function and risk factors with cerebrovascular complications amongst a representative, multi-ethnic urban population. A limitation of this work was that the small number of strokes underpowered the study, and therefore these results are exploratory. Future studies should seek to replicate this work amongst a larger cohort size to overcome this issue.

Click here to read this study in JAMA Cardiology

Relevant reading: Neuroinflammatory mechanisms in ischemic stroke: focus on cardioembolic stroke, background and therapeutic approaches

In-Depth: [prospective cohort]: The Cardiovascular Abnormalities and Brain Lesions (CABL) cohort study was performed amongst community-dwelling older adults. Data were derived from the Northern Manhattan Study, a prospective, cohort study which collected data from adults between 1993 and 2001. Eligible participants in the present study were aged over 40 and had never previously had a stroke. A second cohort of participants over 50 years who had never had a stroke was invited to undergo brain magnetic resonance imaging between 2003 and 2008. Finally, cardiovascular data were derived from patients aged 55 or older beginning in 2005. Risk factors were identified through a history and physical examination, and echocardiography was performed using standardized methods. The mean (standard deviation) left atrial strain was 28.0% (5.3%), positive longitudinal LASR during ventricular systole was 0.94/second (0.23), negative longitudinal LASR during early ventricular diastole was -0.53/second (0.23) and negative longitudinal LASR during atrial contraction was -1.00/second (0.29).

The following factors were independently associated with increased risk of ischemic stroke on univariable analysis: age (p<0.001 per 1-year increase), left ventricular (LV) ejection fraction (p=0.01), LV mass index (p=0.01), β-blocker use (p=0.03), left atrial (LA) minimum volume index (p=0.01), LA emptying volume index (p=0.02), abnormal LV global longitudinal strain (p<0.001), and incident atrial fibrillation (p=0.01).  Patients with ischemic stroke had significantly lower mean LAe (25.7% [4.9%] vs 28.1% [5.3%]; p=0.001), positive LASR during systole (0.90/second [0.25] vs 0.94/second [0.23]; p=0.04), negative LASR during diastole (−0.47/second [0.21] vs −0.53/second [0.23]; p=0.03), and during atrial contraction (−0.89/second [0.31] vs −1.01/second [0.29]; p=0.002).

Univariable and multivariable Cox analysis found that the hazard ratio (HR) for ischemic stroke was significantly higher with the following parameters: positive longitudinal LAe (HR, 3.33; 95% confidence interval [CI], 1.91-5.79), negative longitudinal LASR during LA contraction (HR, 3.23; 95% CI, 1.86-5.59), positive longitudinal LASR during ventricular systole (HR, 2.12; 95% CI, 1.19-3.78), and negative longitudinal LASR during early ventricular diastole (HR, 1.93; 95% CI, 1.06-3.52). These findings were robust to sensitivity analysis consisting of only patients who had brain imaging and echocardiography within three months of each other.

Image: PD

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