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Relation Between Left Atrial Enlargement and Stroke Subtypes in Acute Ischemic Stroke Patients

Objective Increased atrial size is frequently seen in ischemic stroke patients in clinical practice. There is controversy about whether left atrial enlargement (LAE) should be regarded as a risk factor for cerebral infarction. We investigated the association between indexed left atrial volume (LAVI) and conventional stroke risk factors as well as stroke subtypes in acute ischemic stroke patients. Methods One hundred eighty two acute cerebral infarction patients were included in this study. Brain magnetic resonance imaging and transthoracic echocardiography were done for all patients within 30 days of diagnosis of acute cerebral infarction. Echocardiographic LAE was identified when LAVI was more than 27 mL/m2. Stroke subtypes were classified by the Trial of Org 10171 in acute stroke treatment classification. Results There were significant differences between subjects with normal and increased LAVI in prevalence of stroke risk factors including atrial fibrillation (p = 0.001), hypertension (p = 0.000), valvular heart disease (p = 0.011) and previous stroke (p = 0.031). An increased LAVI was associated with cardioembolic subtype with an adjusted odds ratio was 6.749 (p = 0.002) compared with small vessel disease. Conclusion Increased LAVI was more prevalent in those who had cardiovascular risk factors, such as atrial fibrillation, hypertension, valvular heart disease and history of previous stroke. LAE influenced most patients in all subtypes of ischemic stroke but was most prevalent in the cardioembolic stroke subtype. Increased LAVI might be a risk factor of cerebral infarction, especially in patients with cardioembolic stroke subtype.


INTRODUCTION
Stroke is the second leading cause of death in Korea and is associated with severe disability and mortality. 17) The identification and treatment of stroke risk factors has important consequences on the prognosis of stroke. 4)7) Well-known definite risk factors for ischemic stroke include dyslipidemia, hypertension, diabetes mellitus, ischemic heart disease, atrial fibrillation, valvular heart disease, carotid stenosis, cigarette smoking, and obesity. We have frequently seen ischemic stroke patients with left atrial enlargement (LAE) in clinical practice. This condition indicates increased left ventricle (LV) filling pressure and the subsequent remod-eling process in hypertensive heart disease. 3) In the past few years, LAE has been found to be a risk factor for cardiovascular disease, atrial fibrillation, systemic thromboembolism, congestive heart failure (CHF) and stroke. 5)6)8) 12) The Framingham study noted that LAE may be a risk factor for ischemic stroke in men partially mediated by LV mass. 2) However, the role and basic characteristics of LAE in acute cerebral infarction patients have not been sufficiently described in the literature. Especially, the relation between stroke subtypes and LAE is not clear in patients with acute ischemic stroke. In this study, we investigated the relation of LAE at the time of acute ischemic stroke with conventional stroke risk factors and stroke subtypes.   Echocardiographic LAE was identified when the LAVI was larger than 27 mL/m 2 .

Statistical analyses
The data collected included continuous variables

RESULTS
Demographic characteristics of participants are pre-    (Table 3). An increased LAVI risk was present after adjustment for age and sex, and the adjusted odds ratio was 6.749 (p = 0.002) compared with small vessel disease.

DISCUSSION
The major findings of this study were as follows: first, increased LAVI is more common in patients who had cardiovascular risk factors, such as hypertension, valvular heart disease, atrial fibrillation, and previous stroke. Second, increased LAVI influences most patients in all ischemic stroke subtypes, and is especially highly prevalent in the cardioembolic stroke subtype.
Therefore, increased LAVI is more likely a risk factor of ischemic stroke, especially cardioembolic stroke, than normal LAVI.
There are suggestions that LAE is associated with the risk of stroke. 5)6)9)11) A recent study in a hypertensive population revealed that a first-ever ischemic stroke was associated with LAE, and LAVI was the best predictor of stroke in left atrial assessment. 11) They enrolled a hypertensive population with or without first ischemic stroke as study population and there were no differences in ischemic heart disease, parox-  10) An enlarged atrial size may be the consequence of a raised intra-atrial pressure, which diminishes the flow velocity in the left atrial appendage and therefore increases the thrombogenicity and the embolic risk. 13) LAE has been reported to be a potent risk factor for the development of atrial fibrillation. The Framingham Heart Study showed that every 5 mm increment in LA size raised the risk of atrial fibrillation by 39%. 16) The Cardiovascular Health Study noted that LAE was an independent risk factor of new onset atrial fibrillation in older adults and LA with larger than 0.