Left atrial volumes and associated stroke subtypes

BACKGROUND: Cardio embolism and cerebrovascular atherosclerosis are two major mechanisms of stroke. Studies investigating associations between advanced echocardiographic parameters and stroke mechanisms are limited. METHODS: This study is a standardized review of 633 patients admitted to the stroke service of a tertiary care hospital following a standardized stroke investigation and management pathway. Stroke subtypes were characterized using the Causative Classification System, using the hospitals online radiologic archival system with CCS certified stroke investigators. Patients with two mechanisms were excluded. RESULTS: Patients with cardioembolic stroke had a higher proportion of atrial fibrillation (p < 0.001), acute myocardial infarction (p < 0.001) and ischemic heart disease (p < 0.001). On electrocardiogram (ECG) and transthoracic Echo (TTE), patients with cardioembolic stroke had a greater atrial fibrillation (p < .00), left ventricular thrombus (p < .00), left ventricular ejection fraction <30% (p < .00) and global hypokinesia (p < .00) Patients with cardioembolic stroke had higher mean left atrial volume indices (LAVi) (p < 0.001), mean left ventricular mass indices (LVMi) (p < 0.05) and mean left atrial diameters (LAD) (p < 0.05). At LAVi of 29-33 ml/m2, the risk of atherothrombotic stroke increased. The risk of cardioembolic stroke increased with LAVi of 34 ml/m2 and above. CONCLUSION: Left atrial volume indices may be linked to specific stroke phenotype. At mild increases in left atrial dimensions, the risks of atherosclerotic stroke are high, and probably reflect hypertension as the unifying mechanism. Further increases in left atrial dimensions shifts the risk towards cardioembolic stroke.