Association of residual shunts after PFO closure with recurrent stroke risk: Single-center experience

Literature on residual right-to-left shunts after patent foramen ovale (PFO) closure shows conflicting results regarding stroke recurrence risk, although recent data suggest increased risk with moderate and large residual shunts.

To evaluate the effect of the presence and grade of residual shunt on the risk of stroke/transient ischemic attack (TIA) after PFO closure.

We retrospectively analyzed data from a prospectively maintained registry of 498 patients who underwent PFO closure following cryptogenic stroke/TIA between 2004 and 2022. Residual shunts (RS) were classified as grade 0 (none), grade I (<10 microbubbles), grade II (10-20), or grade III (>20) using transesophageal echocardiography and transcranial Doppler at 6 and 12 months. Recurrent ischemic events during 7-year follow-up (mean 5.24 ± 2.0 years) were assessed via medical records. Risk ratios with 95% confidence intervals adjusted for follow-up duration were calculated.

In the study population (median age 52 years), RS was present in 35% of patients at 6 months, decreasing to 19% at 12 months (grade II or III: 13%). The annual risk of TIA/stroke was significantly higher in patients with any RS compared to those without (risk ratio [RR], 3.57; 95% confidence interval [CI], 1.52-8.43), particularly driven by grade III shunts (RR, 3.71; 95% CI, 1.21-11.39).

Although the incidence of residual shunting decreases over time, residual right-to-left shunting following PFO closure is associated with a significantly increased risk of recurrent ischemic stroke or TIA.