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Percutaneous mitral valve repair is effective and safe in a patient population that is at high surgical risk, elderly, and mainly affected by functional mitral regurgitation (MR), according to a European study scheduled to be published online June 4, 2013, ahead of print in the Journal of the American College of Cardiology.

Data from the ACCESS-EU registry were previously presented at the European Society of Cardiology Congress 2012 in Munich, Germany.

Francesco Maisano, MD, of Ospedale San Raffaele (Milan, Italy), and colleagues conducted the ACCESS-EU Phase I postmarketing study to assess the efficacy and safety of MitraClip (Abbott Vascular, Santa Clara, CA) after its CE mark approval in March 2008. The current report includes data on 567 patients with functional or degenerative MR enrolled between April 2009 and 2011 at 14 European centers; treatment with MitraClip varied according to local practice.

Patients had a mean age of 74 years, were at high surgical risk, and had multiple comorbidities. The majority (84.9%) were New York Heart Association (NYHA) functional class III or IV. Most had functional MR (77%). MR was symptomatic or asymptomatic moderate-to-severe (3+) or severe (4+).

MitraClip was successfully implanted in all but 2 patients (99.6%). The procedure improved MR severity vs. baseline, such that nearly 80% of patients had MR severity of 2+ or less at 12 months (P < 0.0001; table 1).

Table 1. MR Severity Over Time

Overall, 88% percent of patients improved by at least 1 MR grade from baseline to 12 months, 53% improved by 2 or more grades, and 16% improved by 3 or more grades. Additionally, 71.4% of patients were NYHA class I or II at 12 months.

Kaplan-Meier estimated survival at 1 year was 81.8%. Overall, MitraClip resulted in low rates of adverse events at 30 days and 12 months (table 2).

Table 2. Adverse Event Rates

A total of 6.3% of patients required mitral valve surgery within 12 months postprocedure. Single leaflet device attachment occurred in 27 patients (4.8%); 10 underwent a second MitraClip procedure, 11 had no additional treatment, 6 underwent surgery, and 1 had additional MitraClip devices implanted during the index procedure. No cases of device embolization were reported.

By 12-month follow-up, 6-minute walk test results had improved by 59.5 ± 112.4 meters vs. baseline (P < 0.0001) and quality of life as measured by responses to the Minnesota Living with Heart Failure Questionnaire had improved by 13.5 ± 20.5 points (P < 0.0001).

“In this patient population, the MitraClip procedure is safe, with low rates of hospital mortality and adverse events,” the study authors conclude. “Longer term follow-up and more in-depth analysis of the data will provide useful insights of the MitraClip therapy in the real world.”

Snapshot of Current Practice with Some Limitations

In an e-mail correspondence, Dr. Maisano told TCTMD that ACCESS-EU is the largest multinational database assessing MitraClip’s post-market use in Europe. “It is a great tool to evaluate real-world outcomes, and it does provide for the first time a reliable snapshot of the current practice,” he said, adding that the registry will also provide data to improve patient selection.

Dr. Maisano pointed out that the current registry is limited by its absence of core-lab adjudicated echo findings, something that has been implemented in the ACCESS-EU II registry.  “However, I do not expect serious differences between the outcomes of ACCESS I versus II,” he noted. “In particular, in a field dominated by functional MR and heart failure, clinical findings are probably more important than MR reduction or other echocardiographic findings.”

Yet Jeffrey Borer, MD, of the State University of New York Downstate Medical Center (New York, NY), cited another drawback to the study.

The major deficiency, “which precludes a rigorous assessment of the appropriateness of performing MitraClip procedures in any specific population, is the lack of a control group of any kind, much less randomization of the procedure versus no procedure in similar patients,” he commented in an e-mail communication with TCTMD.

Additionally, while it appears the procedure can be performed with acceptable safety in most patients, by actuarial analysis, 1 in 5 patients who underwent MitraClip was dead within 1 year, said Dr. Borer. “In fact, the outcome may be even worse—only two-thirds of the patients were actually followed for a year, so true outcome for the population as a whole really is an assumption, a little dangerous in a population of less than 600 subjects.”

Moreover, because surgery very seldom leaves any residual MR, Dr. Borer stressed that a remaining question is why patients underwent MitraClip in the first place. Performing surgery is more prudent if technically possible considering how little is known about MitraClip’s long-term durability, he advised.

Surgery is preferable when degenerative MR occurs in a young patient, explained Dr. Maisano. “In the case of functional MR or in the case of an elderly patient with degenerative MR, MitraClip is probably a better option today.”

Results Consistent and Likely to Improve

Interestingly, the current results gel with those of the EVEREST high-risk registry, which was prospective, included a core lab, and had uniform entry criteria, said Ted Feldman, MD, of Evanston Hospital (Evanston, IL). He told TCTMD in an e-mail communication that results for MitraClip are very consistent across all the various randomized and registry reports.

Practice in the United States will focus on high-risk patients, he added.

If MitraClip receives US Food and Drug Administration (FDA) approval, said Dr. Borer, the greatest concern is that the procedure would be performed in many patients for whom surgery might be far the better option.

According to Dr. Maisano, the procedure is steadily improving. Transcatheter valve intervention as a whole is rapidly evolving with increased expertise, new technology, and better imaging to guide procedures in challenging anatomical situations.

Dr. Feldman agreed that there has been a learning curve and noted “decreasing procedure times and a decrease in the problem of single leaflet device attachment, with improvements over time throughout the research experience everywhere.

In an editorial accompanying the paper, Saibal Kar, MD, of Cedars Sinai Medical Center (Los Angeles, CA), writes that further prospective randomized studies are needed to help practitioners better understand the role of MitraClip in different MR etiologies.

1. Maisano F, Franzen O, Baldus S, et al. Percutaneous mitral valve interventions in the real world: Early and one year results from the ACCESS-EU, a prospective, multicenter, non-randomized post-approval study of the MitraClip therapy in Europe. J Am Coll Cardiol. 2013;Epub ahead of print.

2. Kar S. The percutaneous valve repair: Adding life to years. J Am Coll Cardiol. 2013;Epub ahead of print.

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