Right-to-Left Shunt Through Iatrogenic Atrial Septal Defect After MitraClip Procedure

ObjectivesThe aim of this study was to investigate the incidence, characteristics, hemodynamic conditions, and clinical significance of right-to-left (R-L) shunt through an iatrogenic atrial septal defect (iASD) after the MitraClip procedure.BackgroundR-L shunt through an iASD after the MitraClip procedure has not been well investigated.MethodsFrom 2014 to 2017, 385 consecutive patients with mitral regurgitation underwent the MitraClip procedure. iASD was assessed using intraprocedural transesophageal echocardiography. Right and left heart catheterization was used to assess the hemodynamic status of patients. All patients provided written informed consent for the procedure. All data for this study were collected from an established interventional cardiology laboratory database approved by the Cedars-Sinai Medical Center Institutional Review Board.ResultsR-L shunt was observed in 20 patients (5%). In 7 of these patients (35%), R-L shunt was accompanied by acute deoxygenation. Prevalence of severe tricuspid regurgitation (55% vs. 20%; p = 0.001), serum B-type natriuretic peptide (664 pg/ml [434 to 1,169 pg/ml] vs. 400 pg/ml [195 to 699 pg/ml]; p = 0.006), mean pulmonary artery pressure (38 mm Hg [34 to 45 mm Hg] vs. 29 mm Hg [22 to 37 mm Hg]; p < 0.001), and right atrial pressure (19 mm Hg [13 to 20 mm Hg] vs. 10 mm Hg [7 to 14 mm Hg]; p < 0.001) were significantly higher in patients with R-L shunt than in those with left-to-right shunt. Patients with R-L shunt also showed a more prominent reduction in the left atrial V-wave and mean pressure from baseline to post-procedure compared with those with left-to-right shunt (−22.8 ± 2.6 mm Hg vs. −11.8 ± 0.9 mm Hg [p = 0.002] and −7.9 ± 0.8 mm Hg vs. −4.0 ± 0.4 mm Hg [p = 0.003], respectively).ConclusionsR-L shunt through an iASD was observed in 5% of patients who underwent the MitraClip procedure and in one-third of patients with R-L shunt presented acute deoxygenation. Elevated right atrial pressure concomitant with pulmonary hypertension and significant reduction in left atrial pressure after MitraClip deployment were associated with R-L shunt.