Introduction of Transcatheter Aortic Valve Replacement For Native Aortic Valve Regurgitation

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Summary

Transcatheter aortic valve replacement (TAVR) with either the balloonexpandable Edwards SAPIEN XT valve (Edwards Lifesciences, Irvine, California), or the self-expandable CoreValve prosthesis (Medtronic, Minneapolis, Minnesota) has become the established therapeutic modality for severe aortic valve stenosis in patients who are not deemed suitable for surgical intervention due to excessively high operative risk. In the pivotal Placement of Aortic Transcatheter Valves (PARTNER) randomized trial, TAVR with the Edwards SAPIEN valve prosthesis, compared with conventional therapy, decreased the rate of death at 1 year, reduced cardiac symptoms, and was associated with improvement in valve function.¹ Medium-² and longer-term³ follow-up studies of the PARTNER trial patient cohort demonstrated sustained benefit of TAVR over standard therapy in terms of mortality, functional status, and hemodynamic performance of the aortic valve. In addition, in high-risk patients with severe aortic stenosis (AS), transcatheter aortic valve implantation and surgical replacement of the aortic valve were associated with similar rates of survival at 1 year⁴ and 2 years.⁵

Native aortic valve regurgitation (NAVR), defined as primary aortic regurgitation not associated with AS or failed surgical or TAVR, is still considered a relative contraindication for transcatheter aortic valve therapies. In fact, in the PARTNER trial, patients with severe (grade ≥3) aortic incompetence were excluded from the study, because of the absence of annular or leaflet calcification required for secure anchoring of the transcatheter heart valve and the associated risk for valve dislocation.¹ In addition, severe aortic regurgitation often is accompanied by aortic root or ascending aorta dilatation, the treatment of which mandates operative intervention.

In recent years, TAVR has been sporadically used to treat NAVR in surgically inoperable patients. Initial reports described transcatheter deployment of the Medtronic CoreValve prosthesis or the Edwards SAPIEN XT valve to treat NAVR on a compassionate basis,^6–9 and in special settings such as left ventricular (LV) assist device,^10,11 or heart transplantation.¹² The initial experience has been comprehensively reviewed by Roy et al.¹³

More recently, TAVR for isolated aortic regurgitation has been performed with newer-generation valves, such as the JenaValve (JenaValve Technology, Munich, Germany), the ACURATE TA valve (Symetis, Ecublens, Switzerland), and the Medtronic Engager valve (Medtronic 3F Therapeutics, Inc., Santa Ana, California, US).¹⁴ In addition, new ancillary devices such as the Helio dock have emerged that are specifically designed to stabilize the annulus–root complex, and have been trialled in conjunction with older-generation transcatheter aortic valve prostheses.¹⁵