Abstract TMP88: Prevalence of Right-to-left Cardiac Shunt in the Greek Population is High and Impacts on the Interpretation of the Risk of Paradoxical Embolism (RoPE) Score

Abstract

Introduction: The RoPE score calculates the probability that patent foramen ovale (PFO) is causally related to stroke (PFO attributable fraction, PFO-af), based on PFO prevalence in patients with cryptogenic stroke compared with that in control subjects. The latter has been estimated at 25%; however, PFO prevalence in nonselected populations varies widely. Since PFO prevalence in Greeks remains unknown, we aimed to define it and to calculate PFO-af stratified by RoPE score in a cohort of patients with embolic stroke of undetermined source (ESUS). Methods: Right-to-left cardiac shunt (RLS) was detected according to the international consensus criteria in healthy subjects (H, n=115, women=65) and patients with ESUS (n=84, women=42) ≤55 years old. Each subject underwent unilateral middle cerebral artery transcranial Doppler (TCD) recording (Sonaratek, Natus) with a 2-MHz probe after infusion of agitated saline, at rest and after a controlled Valsalva maneuver. We characterized RLS as large (>20 microbubbles or curtain), moderate (10<x≤20) and minimal (≤10). Statistical comparisons were performed using the Fisher’s exact test. We dichotomized patients with ESUS and PFO into high (>median) and low (≤median) RoPE score groups and calculated the corresponding PFO-af. Results: RLS was detected in 43.5% (50/115) of H and 50% (42/84) of ESUS. Large RLS tended to occur more often in ESUS compared to H [29.8% (25/84)] vs 18.3% (21/115); p=0.06]. The RoPE score median in patients with ESUS and RLS was 8 (interquartile range: 7,9). Patients with high RoPE score (9-10) had PFO-af of 64.4 whereas patients with low score (0-8) had PFO-af of 4.4. For any individual stratum up to RopE score 6, the PFO-af was null. Conclusions: The prevalence of RLS in Greeks is quite higher than the average used by the RoPE study. Despite a 50% chance of having RLS of any size, patients with ESUS have large RLS at least 60% more often than the general population. We suggest that optimal calculation of the PFO-af corresponding to RoPE score strata relies on the accurate estimation of PFO prevalence in national/ethnic populations. The proposed RoPE score cutoff of >6 for having a probable PFO-related stroke may overestimate the probability in patients deriving from populations with high RLS prevalence.