The mechanical integrity of the MitraClip device for repair of the mitral valve was maintained for up to five years and with complete healing, according to a subset of data from the EVEREST (Endovascular valve edge-to-edge repair study) study presented on 22 September 2009 at the Transcatheter Cardiovascular Therapeutics (TCT) Conference in San Francisco.
The data also show complete fibrous encapsulation of the MitraClip device with organised, endocardial tissue growth demonstrating complete healing and incorporation of the implant within the native mitral valve. Additionally, no significant stenosis or inflammation was observed beyond 300 days.
The data were presented by Renu Virmani, president and Medical Director, CVPath Institute. The EVEREST study was designed to evaluate the MitraClip system for the treatment of mitral regurgitation.
In the EVEREST study, 16 MitraClip devices were explanted greater than 300 days after implantation. During explant surgery, the fibrous capsule often requires dissection in order to perform surgical repair of the valve. Virmani reports on three MitraClip explants with minimal tissue disturbance. In these three MitraClip explants, a fibrous tissue bridge with a mean thickness of 10.01+/-2.09mm was observed over and between the MitraClip device arms resulting in tissue continuity between the two valve leaflets. Tissue growth over the MitraClip device arms had a mean thickness of 0.82+/-0.74mm. There was no, or minimal, inflammation and no evidence of infection or stenosis. None of the16 long-term MitraClip implants studied demonstrated any evidence of wear, component fracture or corrosion for up to five years.
“The long-term data demonstrate device integrity over time and healing as expected for patients that have received the MitraClip therapy,” said Virmani. “These results are especially promising considering the potential need for future surgery in some patients. There are no histo-pathologic indications that suggest that future surgical options may be impaired in patients with long-term implantation of the MitraClip device.”
The MitraClip system is the first commercially available treatment option for non-surgical mitral valve repair for patients suffering from the effects of mitral regurgitation in Europe. The MitraClip system is currently in late stage clinical trials in the US.
Other results
Significant left ventricular reverse remodeling in patients with sustained reduction of mitral regurgitation
Sustained reduction of mitral regurgitation following mitral valve repair with the MitraClip system in patients with degenerative mitral regurgitation or functional mitral regurgitation led to heart function improvements, according to 12-month data from a subset of the initial registry cohort of the EVEREST (Endovascular valve edge-to-edge repair study) studies presented at the TCT Conference.
The data were presented by Scott Lim, interventional cardiologist at the University of Virginia Medical Center and one of the EVEREST trial investigators.
This subset of the initial EVEREST registry cohort was comprised of 79 patients with moderate-to-severe or severe mitral regurgitation who had discharge mitral regurgitation reduction to grade 2+ or less. Of the 79 patients, 73% had degenerative mitral regurgitation and 27% had functional mitral regurgitation, and 49 continued with a MitraClip device with mitral regurgitation less than or equal to grade 2+ at 12 months. Matched core laboratory echocardiographic data were available at baseline and 12 months. Mean mitral regurgitation grade reduced from 3.1+/-0.7 at baseline to 1.4+/-0.5 at 12 months. Multiple indices of left ventricle function improved significantly (LV volumes, LV mass, LV sphericity and forward stroke volume), and there was no significant change in annular dimensions.
“The 12 month data seen here in the initial cohort continue to add to the body of clinical evidence that demonstrate that the MitraClip therapy may be a clinically beneficial treatment for patients suffering from degenerative or functional mitral regurgitation,” said Lim. “The results we have seen in the EVEREST trials potentially expand the range of treatment options available to select patients, including those who are not good candidates for surgery.”
Significant reduction in mitral valve annulus dimensions in high-risk patients with functional mitral regurgitation
Twelve-month data from EVEREST II (Endovascular valve edge-to-edge repair study) study high-risk registry arm presented on 22 September 2009 at the TCT Conference show that high-risk patients with functional mitral regurgitation following valve repair with the MitraClip showed a reduction in mitral annular dimension, improvement in heart function and a reduction in hospitalisation for congestive heart failure.
The data were presented by Saibal Kar, director of interventional cardiac research at Cedars-Sinai Medical Center, Los Angeles, and the lead enrolling investigator of the EVEREST II trial.
This data included 34 patients from the high-risk registry with moderate-to-severe or severe functional mitral regurgitation who received a MitraClip device and had matched core laboratory echocardiographic data at baseline and 12 months. Results included a mean mitral regurgitation grade reduction from 3.2+/-0.5 at baseline to 1.8+/-0.9 at 12 months. In addition to the reduction of mitral regurgitation, there was significant reduction in the systolic and diastolic septo-lateral mitral annular diameter as well as a significant reduction in left ventricular end diastolic and systolic volumes. Left ventricular ejection fraction did not change significantly from baseline, while forward stroke volume improved, indicating improved cardiac efficiency.
“We were pleased to see that in addition to a reduction in mitral regurgitation, patients had significant reductions in left ventricle size and mitral annual diameter we believe contributes to an improved quality of life,” said Kar. “With this therapy, we have been able to expand the options available to selected patients who are at high risk for more invasive treatments, and help them to avoid the risks associated with surgery. We look forward to validating these important findings with ongoing studies.”
