TVT Registry: MitraClip Holds Up Well in Early US Commercial Experience
SAN DIEGO, CA—Initial US use of transcatheter mitral valve repair (TMVR) has resulted in high procedural success and low complication rates, according to registry findings presented at the American College of Cardiology/i2Scientific Session on March 15, 2015.
MitraClip (Abbott Vascular) received FDA approval in October 2013 for the treatment of patients with symptomatic degenerative mitral regurgitation (MR) grade ≥ 3 at prohibitive surgical risk.
Presenting data from the Society of Thoracic Surgeons (STS)/American College of Cardiology (ACC) Transcatheter Valve Therapy (TVT) Registry, Paul Sorajja, MD, of Abbott Northwestern Hospital (Minneapolis, MN), said the experience has been favorable in comparison to preapproval studies and other national registries.
“We do believe these data help demonstrate the effectiveness of TMVR and its safety for the treatment of patients who are at prohibitive risk and have symptomatic mitral regurgitation,” he added.
Researchers led by Dr. Sorajja examined outcomes pf 564 patients (median age 83 years; 56% men) who received MitraClip at 61 hospitals between November 2013 and August 2014. All patients were enrolled in the TVT Registry, which collects patient-level data from all patients undergoing commercial MitraClip procedures in the United States. Median number of cases per site was 6 (range 1-58).
Severe comorbidities were common and included NYHA class III/IV heart failure (83.9%), A-fib (62.6%), and hospitalization for heart failure in the prior year (51.8%). More than half of patients were classified as frail, and the median STS-PROM score for mitral valve repair was 7.9%. Median LVEF was 56%, and 94% of patients had MR grade 3 or 4. MR was degenerative in 85.5% and functional in 14.4%.
Favorable Outcomes Seen
Overall, procedural success was achieved in 91.8% of patients, with a complication rate of 7.8% and device-related adverse event rate of 2.7%. Mean length of hospital stay was 3 days, with 81.9% of patients discharged directly to home. After implantation, 93% of patients had MR grade ≤ 2 and 63.7% MR grade ≤ 1.
In-hospital mortality was 2.3%, and 30-day mortality was 5.8%. Rates of stroke and major bleeding were 1.8% and 3.9%, respectively, and 8% of patients were readmitted for heart failure. In exploratory analyses, LV end-diastolic volume and baseline MR grade predicted more residual MR (P = .03 for both), while implantation at the A2-P2 location and higher case volume per site predicted less MR (P = .01 for both).
Unclear Why—or Whether—Clip Location Matters
Dr. Sorajja noted that compared with other registries, the population in the TVT Registry is older with a higher prevalence of degenerative MR. Yet its rate of MR reduction after MitraClip placement was “quite comparable,” as was that of in-hospital death.
Panelist Frank E. Silvestry, MD, of the Hospital of the University of Pennsylvania (Philadelphia, PA), said he was struck by the fact that the results suggest that a central clip location is highly effective, while a noncentral location is not. This finding “flies in the face” of what has been reported so far from investigators outside the United States, he said.
Dr. Sorajja replied: “It’s hard to know if that just means that [A2-P2] is the best place to implant or if the patients who were selected for A2-P2 implantation had higher success rates because technically it’s much easier.”
Panelist Mark Reisman, MD, of the University of Washington Medical Center (Seattle, WA), noted that 10% of all cases in the registry were from a single center. This, he said, may explain why case volume was associated with greater reductions in MR.
Dr. Sorajja cautioned against reading “too much into that,” but acknowledged it does “speak to the fact that there is a learning curve to the procedure that we have to appreciate.”
Source:Sorajja P. Outcomes of the initial experience with commercial transcatheter mitral valve repair in the U.S.: a report from the STS/ACC TVT Registry. Presented at: American College of Cardiology/i2 Scientific Session; March 15, 2015; San Diego, CA.
- Dr. Sorajja reports receiving consulting fees/honoraria from Abbott Vascular, Lake Region Medical, and Medtronic and serving on the speaker’s bureau for Abbott Vascular and Boston Scientific.
- Dr. Silvestry reports receiving research grants from DC Devices and Siemens Medical.
- Dr. Reisman reports receiving consulting fees/honoraria from Boston Scientific and having ownership interest/partnership/principal in Biostar Ventures.
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