The Patent Foramen Ovale (PFO)-Associated Stroke Causal Likelihood classification system combines information regarding noncardiac patient features (vascular risk factors, infarct topography) and PFO features (shunt size and presence of atrial septal aneurysm [ASA]) to classify patients into 3 validated categories of responsiveness to treatment with PFO closure. However, the distinctive associations of shunt size and ASA, alone and in combination, have not been completely delineated.

To evaluate the association of PFO closure with stroke recurrence according to shunt size and/or the presence of an ASA.

Pooled individual patient data from 6 randomized clinical trials conducted from February 2000 to October 2017 that compared PFO closure with medical therapy. Patients in North America, Europe, Australia, Brazil, and South Korea with PFO-associated stroke were included. Analysis was completed in January 2022.

Transcatheter PFO closure plus antithrombotic therapy vs antithrombotic therapy alone, stratified into 4 groups based on the combination of 2 features: small vs large PFO shunt size and the presence or absence of an ASA.

Recurrent ischemic stroke.

A total of 121 recurrent ischemic strokes occurred in the pooled 3740 patients (mean [SD] age, 45 [10] years; 1682 [45%] female) during a median (IQR) follow-up of 57 (23.7-63.8) months. Treatment with PFO closure was associated with reduced risk for recurrent ischemic stroke (adjusted hazard ratio [aHR], 0.41 [95% CI, 0.28-0.60]; P < .001). The reduction in hazard for recurrent stroke was greater for patients with both a large shunt and an ASA (aHR, 0.15 [95% CI, 0.06-0.35]) than for large shunt without ASA (aHR, 0.27 [95% CI, 0.14-0.56]), small shunt with ASA (aHR, 0.36 [95% CI, 0.17-0.78]), and small shunt without ASA (aHR, 0.68 [95% CI, 0.41-1.13]) (interaction P = .02). At 2 years, the absolute risk reduction of recurrent stroke was greater (5.5% [95% CI, 2.7-8.3]) in patients with large shunt and ASA than for patients in the other 3 categories (1.0% for all).

Patients with both a large shunt and an ASA showed a substantially greater beneficial association with PFO closure than patients with large shunt alone, patients with small shunt and ASA, and patients with neither large shunt nor ASA. These findings, combined with other patient features, may inform shared patient-clinician decision-making.