Left Atrial Enlargement in Primary Cryptogenic Strokes Without Atrial Fibrillation

The relationship between left atrial enlargement (LAE) and primary cryptogenic stroke (PCS) remains a mystery. LAE has been proposed to be an independent risk factor of PCS, recurrent ischemic strokes, paroxysmal atrial fibrillation, and thromboembolism. Our study evaluates the prevalence of LAE among patients with PCS in the absence of atrial fibrillation, unlike previous studies that included atrial fibrillation, in order to isolate LAE as a risk factor. We hypothesize there is a direct correlation between the prevalence of LAE and the incidence of PCS. Our multi-center, retrospective, cross-sectional study constructed a database of 646 patients identified with a diagnosis of cerebral infarction over a three-year period. Detailed chart review excluded all patients with known etiologies for stroke, including atrial fibrillation, atrial flutter, prior stroke, systolic heart failure, carotid artery stenosis, patent foramen ovale, thromboembolic disease, previous anticoagulation, or an active cancer diagnosis. Diagnosis of LAE utilized a composite of criteria for transthoracic echocardiogram measurements, including left atrial diameter (LAD) and left atrial volume index (LAVI). All study criteria were met by 154 patients (24%) for analysis, where baseline characteristics included: 79 (51%) male, 104 (67.5%) Caucasian ethnicity, 108 (70%) diagnosed of hypertension (HTN), 80 (52%) previous or current tobacco users, and 47 (31%) diagnosed of diabetes (DM). We utilized logistic regression modeling to examine correlations in our population. Our preliminary analysis found that 74 (48%) patients met at least one criterion for LAE. The mean LAD for patients with and without LAE was 4.1 cm and 3.4 cm, respectively (SD 0.87 vs 0.55, p<0.0001). The mean LAVI for patients with and without LAE was 29.68 mL/m² and 18.44 mL/m², respectively (SD 7.37 vs 5.13, p<0.0001). Our findings support the significance of LAE as a risk factor for cases of PCS. Multiple risk factors were identified in our study population that reflect the importance of preventative counseling for patients with HTN, hyperlipidemia, history of tobacco use, and DM. Routine screening for LAE in patients who suffer a PCS will encourage additional research that may elucidate the clinical relevance of identifying LAE in PCS. For example, whether LAE alone or in the setting of specific comorbidities warrants universal screening practices such as closer monitoring of arrhythmias such as paroxysmal atrial fibrillation to initiate anticoagulation earlier. Additionally, randomized control trials are necessary to determine whether prophylactic anticoagulation reduces future stroke risk among patients identified with LAE.