Transapical transcatheter mitral valve implantation shows promise

Two older patients with severe functional mitral regurgitation underwent successful transapical transcatheter mitral valve implantation in a recent study.

Researchers of the study, which was published in the Journal of the American College of Cardiology, noted that old age, comorbidities or severe left ventricular dysfunction prevent some patients with mitral regurgitation from being recommended for surgery. In this high-risk patient cohort, transapical transcatheter mitral valve implantation may be an attractive option.

This approach was used in two patients — a 73-year-old man and a 61-year-old woman — with severe functional mitral regurgitation, NYHA class IV HF, depressed LV ejection fraction, pulmonary hypertension and additional comorbidities.

Clinicians used general anesthesia in both patients. The device (Tiara, Neovasc) was implanted uneventfully in both patients, according to the researchers, and both patients were extubated in the operating room. Results indicated hemodynamic stability and no need for cardiopulmonary bypass in both patients. There were increases in systemic arterial pressure and stroke volume coupled with decreases in pulmonary pressure immediately after the procedure.

Low transvalvular gradient and no LV outflow tract obstruction were reported following echocardiograms conducted at 48 hours, 1 month and 2 months after the procedure.

One patient demonstrated a trivial paravalvular leak at the 48-hour mark. This leak was resolved at subsequent follow-up

“Transapical transcatheter mitral valve implantation is technically feasible and can be performed safely,” the researchers concluded. “Transcatheter mitral valve implantation may become an important treatment option for patients with severe [mitral regurgitation] who are at high operative risk.”

Complicated anatomy

David H. Adams

Anelechi C. Anyanwu, MD, and David H. Adams, MD, of the department of cardiovascular surgery at Mount Sinai Medical Center in New York, wrote in an accompanying editorial that because of the intricate pathoanatomy and lack of a rigid landing zone of the mitral valve, this transcatheter mitral valve prosthesis has a complex design, including anchoring mechanisms to prevent migration into the atrium during ventricular contraction.

“The prosthesis is not a symmetrical tube, but conforms to the typical D-shape of the mitral valve annulus,” they wrote, adding that that this design is in contrast to transcatheter aortic valve replacement prostheses. “Although prosthesis development and technical execution of transcatheter mitral valve replacement [TMVR] present unique challenges, these [two] patients with successfully deployed catheter mitral valves demonstrate that these challenges are not insurmountable,” they wrote.

“Cheung et al. are to be congratulated for their pioneering effort, which serves as a proof-of-concept for transcatheter replacement in the non-calcified mitral valve,” Anyanwu and Adams continued. “This makes it probable that routine application of TMVR will be technically possible in the near future, leading the authors to question whether TMVR will revolutionize therapy for mitral valve disease, mirroring the course of TAVR.”

Dealing with the mitral valve

Anyanwu and Adams noted several differences between the mitral valve and the aortic valve that may aid clinicians in understanding how transcatheter mitral valve platforms should be developed.

For example, the heterogeneity of mitral valve disease is a factor, as is the fact that mitral valve disease does not always impact older individuals, as aortic disease does. Clinicians should be aware of the success of current mitral valve repair interventions and of risks to surrounding structures. Paravalvular leak also should be taken into account.

“Paravalvular leakage remains the Achilles’ heel of transcatheter valve replacement,” the editorialists wrote. “Such leaks may be more likely in the mitral than in the aortic position.”

Anyanwu and Adams added that particular attention should be paid to the tricuspid valve. “Any transcatheter solution to advanced mitral valve disease that does not include a solution for the tricuspid valve may be of limited efficacy in many patients,” they wrote.

Clinicians should understand which patients are inoperable and understand that mitral valve disease is not associated with high short-term mortality, according to Anyanwu and Adams.

“In addition to overcoming the technical hurdles of mitral valve replacement via transatrial, transapical or transfemoral approaches, valve specialists should further consider prerequisites for application in clinical practice and the target patient subgroups,” they wrote. “Although transcatheter valve replacement for de novo valve disease would be a true game changer for subsets of patients, current surgical data and experience suggest that surgical valve repair and replacement will remain dominant therapies in the near term.”

For more information:

Anyanwu AC. J Am Coll Cardiol. 2014;64:1820-1824.

Cheung A. J Am Coll Cardiol. 2014;64:1814-1819.

Disclosure: The researchers report financial disclosures with Neovasc. Adams and Anyanwu report financial disclosures with Edwards Lifesciences and Medtronic.