A Trainee’s Notes on the MitraClip: MITRA-FR versus COAPT
As an internal medicine resident, I’ve been peripherally involved in managing patients undergoing percutaneous mitral valve repair and conducting research on procedural outcomes. Developed as an alternative to conventional mitral valve surgery, the MitraClip device provides a percutaneous means to treat mitral regurgitation (MR). The device was originally approved for degenerative MR based on data from the EVEREST trials. As recent headlines show, the role for MitraClip in functional MR is the subject of ongoing debate.
Marking a first stab at answering this question, the MITRA-FR trial gave us a neutral result. In spite of symptomatic improvement, there was no reduction in the primary composite endpoint of all-cause mortality and cardiac rehospitalization. Shortly thereafter, the COAPT trial offered new hope, demonstrating a marked reduction in cardiac rehospitalization (NNT=3.1) and mortality (NNT=5.9).
There are a few ways to reconcile these differences. MITRA-FR enrolled half as many patients and followed them for half as long compared to COAPT; therefore, the study may have lacked statistical power. Others have questioned operator experience, pointing to a high proportion of patients in MITRA-FR with significant residual MR. Finally, patients in the COAPT study had more severe MR and less dilated ventricles, making them better candidates for valve repair. In MITRA-FR patients with very low ejection fraction, valve repair may have had negligible effect in the face of severe underlying cardiomyopathy.
This last point underscores the importance of patient selection and the need to identify prognosticators of clinical outcomes. To this end, my mentors and I conducted a retrospective review of patients undergoing percutaneous mitral valve repair at Emory University Hospital. We found that intraprocedural improvement in pulmonary venous doppler waveforms predicted 1-year survival and freedom from cardiac rehospitalization in both degenerative MR and functional MR subgroups.
It’s exciting to “grow up” and enter the field of cardiology in an era of advanced structural interventions. On the horizon, RESHAPE-HF is yet another study examining the role for MitraClip in functional MR. The results are highly anticipated, and I hope it brings clarity to this contentious topic.
- Obadia J-F, Messika-Zeitoun D, Leurent G, et al. Percutaneous repair or medical treatment for secondary mitral regurgitation. N Engl J Med 2018;379(24):2297-2306.
- Stone GW, Lindenfeld JA, Abraham WT, et al., on behalf of the COAPT Investigators. Transcatheter Mitral-Valve Repair in Patients With Heart Failure. N Engl J Med 2018;379:2307-18.
- Corrigan FE III, Chen JH, Maini A, et al. Pulmonary venous waveforms predict rehospitalization and mortality after percutaneous mitral valve repair. J Am Coll Cardiol Img 2018;11:xxx–x.