Objective To evaluate the frequency of and risk factors for stroke as a presenting feature in adult patients with secundum atrial septal defect (ASD); rates of post-closure atrial fibrillation (AF) and stroke were also assessed.

Methods We retrospectively reviewed adult patients who presented with an ASD between 2002 and 2018, excluding those with known atrial arrhythmias. Risk factors for stroke were identified using multivariable logistic regression. Post-closure stroke was evaluated using survival analysis stratified by the presence of post-procedure AF.

Results Of 346 patients with ASD (median age 44 years), 34 (10%) presented with a history of stroke. Independent risk factors included elevated body mass index over 25 (OR: 18.2; 95% CI: 4.0 to 82.2; p<0.001), smoking (OR: 9.5; 95% CI: 3.8 to 23.9; p<0.001) and a prominent Eustachian valve (OR: 9.2; 95% CI: 3.4 to 25.2; p<0.001). A scoring system based on these three parameters provided robust stroke risk stratification. During a median follow-up of 12 months after closure, 12 patients (4%) experienced AF and 4 patients (1%) had a new stroke. AF was highly associated with development of stroke post-closure (p<0.001).

Conclusions In this study population, the incidence of stroke prior to ASD closure among patients without atrial arrhythmias was 10%. Risk factors included obesity, smoking and prominent Eustachian valve anatomy. Lifestyle changes should be recommended for at-risk patients, and it may be reasonable to consider ASD closure in the absence of haemodynamic indications in patients at increased risk of stroke.