Iatrogenic Atrial Septal Defect Gradient for Intraprocedural Success After M-teer

Iatrogenic ASD Gradient as a Marker of Residual Mitral Regurgitation Severity After M-TEER Procedure

Transcatheter mitral edge-to-edge repair (M-TEER) has become an established minimally invasive therapy for patients with severe mitral regurgitation (MR) who are at high or prohibitive surgical risk. However, accurate quantification of residual MR after M-TEER remains challenging. In this direction, the hemodynamic significance of the post-procedural iatrogenic atrial septal defect (iASD) gradient is unknown. The objective of this study is to assess the relationship between the post-procedural iASD pressure gradient and the severity of residual MR with intraprocedural echocardiographic and hemodynamic parameters.

The present study plans to enroll patients with high or prohibitive surgical risk and moderate-to-severe or severe symptomatic MR, despite the administration of maximally tolerated doses of guideline-directed medical therapy and, if appropriate, cardiac resynchronization therapy. Patients with severe tricuspid regurgitation, post-procedural transmitral gradient >5 mmHg, right-to-left shunt requiring iASD closure, or refusal to provide written informed consent will be excluded. All intraoperative transesophageal echo loops will be acquired using an EPIQ ultrasound system (Philips, Eindhoven, Netherlands) with an X8-2t transesophageal probe. At the end of the procedure, in the mid-esophageal aortic valve short-axis view, flow across the iASD will be assessed immediately after catheter withdrawal from the left atrium using continuous-wave Doppler interrogation. Through a cardiac cycle, the mean pressure gradient between the left and right atria will be calculated while maintaining hemodynamic stability. Digitally stored image loops will be analyzed offline. Blinded analysis will be performed by an independent investigator. For assessment of residual MR, multiplanar reconstruction will be used, and the largest systolic 3D-VCA will be measured. When multiple regurgitant jets are present, the total regurgitant orifice area will be calculated as the sum of the individual 3D-VCAs. The primary endpoint is to determine the association and diagnostic performance of the post-procedural mean left-to-right iASD pressure gradient, measured immediately after catheter withdrawal, for identifying moderate-or-greater residual mitral regurgitation after M-TEER, as assessed by blinded offline 3D-VCA analysis.

Inclusion Criteria:

• patients with high or prohibitive surgical risk and moderate-to-severe or severe symptomatic MR, despite the administration of maximally tolerated doses of guideline-directed medical therapy and, if appropriate, cardiac resynchronization therapy
• patients undergoing M-TEER as a bridge to heart transplantation

Exclusion Criteria:

• Patients with post-procedural transmitral gradient ≥5 mmHg,
• Patients with right-to-left shunt requiring iASD closure,
• Patients, who decline to provide written informed consent.