Importance of direct right-to-left shunt as high-risk patent foramen ovale associated with cryptogenic stroke

Area of Science:

• Cardiology
• Neurology
• Medical Imaging

Background:

• Transcatheter closure of patent foramen ovale (PFO) is effective for preventing cryptogenic stroke (CS).
• Identifying high-risk PFO associated with CS is crucial for effective treatment.
• Direct right-to-left (RL) shunt through PFO is a potential marker for CS risk.

Purpose of the Study:

• To clarify the importance of direct RL shunt timing through PFO in identifying high-risk PFO associated with CS.
• To evaluate the association between direct RL shunt and CS.
• To determine the incremental value of direct RL shunt in detecting CS risk.

Main Methods:

• Analysis of 137 patients with and without CS confirmed to have PFO.
• Evaluation of RL shunt timing via cardiac cycles after right atrium opacification using saline contrast transesophageal echocardiography.
• Definition of direct RL shunt as microbubbles crossing PFO before or during right atrium opacification.

Main Results:

• Shorter cardiac cycles for microbubble crossing in CS patients (2.0 ± 2.2 vs. 5.5 ± 1.1, p < 0.01).
• Direct RL shunt more frequent in CS patients (77% vs. 29%, p < 0.01) with 79% sensitivity and 71% specificity.
• Direct RL shunt associated with atrial septal aneurysm and low-angle PFO; increased CS detection to 83% when added to large RL shunt.

Conclusions:

• Direct RL shunt is associated with CS and offers incremental value in detecting CS-associated PFO.
• RL shunt timing is a valuable indicator for identifying high-risk PFO.
• Direct RL shunt assessment enhances the prediction of cryptogenic stroke risk in PFO patients.