Edith Lubos (Department of General and Interventional Cardiology, University Heart Center, Hamburg, Germany) and others report in the Journal of the American College of Cardiology that effective regurgitant orifice area, mitral valve orifice area, and transmitral pressure gradient are independent predictors of acute procedural failure in high-risk patients undergoing percutaneous mitral valve repair (MitraClip, Abbott Vascular).
Lubos et al write that percutaneous mitral valve repair with the MitraClip device is now an accepted treatment for patients with significant mitral regurgitation who are deemed to be at high risk for surgery. However, they add that primary procedure failure rates of 9%–23% have been reported and, to date, the predictors of acute procedural outcome have not been assessed. The authors comment: “To further improve technique and possibly allow appropriate patient selection, identification of such predictors is of paramount importance. We sought to assess the acute procedural outcomes of 300 consecutive patients who underwent MitraClip implantation at our institution and determine variables affecting procedural failure.”
The 300 patients at their centre who received the Mitraclip had either grade 3+ (moderate-to-severe) or grade 4+ (severe) mitral regurgitation and were not amenable to surgery. Procedure failure occurred in 32 patients—either because of failure to implant the clip (11 patients) or because of failure to reduce mitral regurgitation severity to ≤2+ despite clip implantation (21 patients). Lubos et al found that significantly more patients with degenerative mitral regurgitation experienced procedure failure than those with functional mitral regurgitation (16.8% vs. 7.8%, respectively; p=0.0259) but did not observe any differences between these groups in terms of the type of procedure failure.
In multivariate analysis, effective regurgitant orifice area and mean transmitral pressure gradient were found to be independent predictive of overall procedure failure. The authors explain that the risk of failure increased by 21% per 10mm2 increase in effective regurgitant orifice area and by 26% per 1mmHg increase in transmitral pressure gradient. They add: “For clip failure, an effective regurgitant orifice area of ≥70.8mm2 and a transmitral pressure gradient of ≥4mmHg were independently predictive whereas transmitral pressure gradient of ≥4mmHg and mitral valve orifice area of ≤3cm2 were independently predictive of an aborted procedure.” However, Lubos et al report that effective regurgitant orifice area was the most significant predictive of overall acute procedural outcome.
Concluding, the authors report that “regardless of mitral regurgitation aetiology”, effective regurgitant orifice area, mitral valve orifice area and transmitral pressure gradient are independent predictors of acute procedure failure in high-risk patients undergoing percutaneous mitral valve repair with the MitraClip device. They note: “These variables thus evolve as readily assessable, well-validated variables to guide patient selection for MitraClip therapy.”
Study author Volker Rudolph (Department of General and Interventional Cardiology, University Heart Center, Hamburg, Germany) told Cardiovascular News: “We think that the decision to use a MitraClip device is an individualised decision. Our data just provide a tool for guiding this decision but should not be regarded as ‘absolute’. Thus, in very high risk patients lacking further therapeutic options, it is certainly reasonable to accept a higher risk for procedural failure.”