In-hospital outcomes of acute ischaemic stroke patients with atrial septal defect. A national inpatient sample study.

Background and aims: Atrial septal defects (ASD) are a well-recognised risk factor for acute ischaemic stroke (AIS). We aimed to delineate the relationship between ASD and in-hospital AIS outcomes (mortality, severe stroke (National Institutes of Health Stroke Scale (NIHSS) > 15), prolonged hospitalisation > 4 days and routine home discharge) in contemporary practice using data from the United States National Inpatient Sample.

Methods: NIS admissions with a primary diagnosis of AIS between 2016-2018 were extracted. The NIHSS variable had 75% missing data, which were imputed using multiple imputations by chained equations. The relationship between ASD and the main outcomes was modelled using multivariable logistic regressions, adjusting for age, sex, comorbidities, stroke severity and revascularisation therapies.

Results: 245,859 records representative of 1,229,295 AIS admissions were included, 35,840 (2.91%) of whom had ASD. ASD patients were younger (median age 63 years versus 72 years) and less likely to have traditional cardiovascular risk factors than their counterparts without ASD. ASD was independently associated with 58% lower odds of in-hospital mortality (hazard ratio (95% confidence interval) = 0.42 (0.33-0.54)), 18% lower odds of severe stroke (0.82 (0.71-0.94)), 20% higher odds of routine home discharge (1.20 (1.14-1.28)) and 28% higher odds of prolonged hospitalisation (1.28 (1.21-1.35)).

Conclusions: ASD was associated with better in-hospital outcomes, which were likely driven by younger age, lower prevalence of traditional cardiovascular risk factors, and lower stroke severity. Further research is warranted to clarify the ASD anatomical characteristics which are most strongly associated with these associations.