Patent Foramen Ovale Channel Morphometric Characteristics Associated with Cryptogenic Stroke: The MorPFO Score

Background: It is still disputable whether the specific morphologic properties of patent foramen ovale (PFO) may contribute to the occurrence of stroke. The aim of this study was to evaluate the differences in the morphometric and functional features of the PFO channel in patients with cryptogenic stroke and those without stroke.

Methods: PFO channel morphology in 106 consecutive patients with cryptogenic stroke and 93 control patients without stroke with diagnosed PFO (by transesophageal echocardiography) was analyzed using transesophageal echocardiography. A validation cohort was established that consisted of 31 patients with cryptogenic stroke and 30 without stroke.

Results: Multivariable regression logistic analyses indicated PFO channel length change (odds ratio [OR], 2.50; 95% confidence interval [CI], 1.75-3.55; P < .001), PFO length/height ratio during the Valsalva maneuver (OR, 0.75; 95% CI, 0.60-0.95; P = .015), septum primum thickness (OR, 0.34; 95% CI, 0.14-0.80; P = .013), septum secundum height (OR, 0.91; 95% CI, 0.84-0.98; P = .013), the presence of an atrial septal aneurysm (OR, 3.38; 95% CI, 1.27-8.97; P = .014), and large shunt (OR, 2.49; 95% CI, 1.13-5.46; P = .022) as PFO-related stroke factors. The Morphologic Stroke Factors of PFO (MorPFO) score was developed, in which six factors were included: PFO channel length reduction (≥21%; 7 points), short septum secundum (<8.6 mm; 5 points), thin septum primum (<1.6 mm; 3 points), large right-to-left shunt (3 points), low PFO channel length/height ratio during the Valsalva maneuver (≤2.1; 2 points), and atrial septal aneurysm presence (1 point). Patients with scores of 0 to 7 points have low-risk PFO channels, those with scores of 8 to 11 points have intermediate-risk PFO channels, and those with scores of 12 to 21 points have high-risk PFO channels. External validation showed good MorPFO score performance (C index = 0.90).

Conclusions: Transesophageal echocardiography can be used to differentiate pathogenic from incidental PFO channels on the basis of their morphologic characteristics. The MorPFO score may help identify high-stroke-risk PFO channels.