Prevalence and echocardiographic features of iatrogenic atrial septal defect after catheter-based mitral valve repair with the MitraClip system.

OBJECTIVES: Review the prevalence, echocardiographic features and potential predictors of iatrogenic ASD (iASD) created with the MitraClip guiding catheter.

BACKGROUND: Catheter-based repair of mitral regurgitation (MR) with the MitraClip device (Abbott Vascular, Menlo Park, CA), is performed through a 22-French transseptal guiding catheter. The echocardiographic prevalence of iASDs after the MitraClip procedure has not been reported.

METHODS: Thirty subjects undergoing MitraClip repair during the roll-in phase of the EVEREST II randomized trial who had baseline, 30 day, 6 and 12 month transthoracic echocardiograms (TTEs) available for review were included. Patients who underwent surgery for MR within the first 12 months were excluded. Residual iASD size, right ventricular (RV) size, left atrial (LA) volume, and tricuspid/MR grade were quantified.

RESULTS: iASDs were found at 12 months in 8 patients (27%) with a mean diameter of 6.6 ± 3.1 mm. Subjects with iASD at 12 months had more residual MR, increased TR and a trend toward larger LA volumes than non-iASD patients. 83% of non-ASD patients were free from MR > 2+ at 12 mos. vs. 38% of those with iASD (p=0.016). There were no other significant associations between clinical and echocardiographic variables and the persistence of iASD.

CONCLUSIONS: After MitraClip repair, persistent iASDs occur at a rate comparable to reports after other transseptal interventional procedures and do not appear hemodynamically significant. Patients with persistent iASDs had less MR reduction at 12-months and a trend toward larger LA volumes, suggesting that increased LA pressure may be a mechanism for persistent iASD.