CHICAGO — Percutaneous mitral leaflet repair using the investigational MitraClip device in patients with functional mitral regurgitation improves symptoms, reduces echocardiographic mitral regurgitation severity, and results in favorable left ventricular remodeling over time, according to preliminary results of a small pilot study.
The MitraClip procedure is designed to mimic percutaneously the edge-to-edge Alfieri isolated leaflet open-chest surgical repair. Placed via a transseptal approach, the MitraClip creates a double-orifice, figure eight-shaped mitral valve by coapting tethered leaflets, thereby reducing the force of closure, Dr. James Hermiller explained at the annual meeting of the American College of Cardiology.
The future outlook for the percutaneous procedure proved to be a matter of disagreement at the meeting, however.
Dr. Hermiller reported that of 23 patients with moderate to severe functional mitral regurgitation (FMR) enrolled in the multicenter uncontrolled first Endovascular Valve Edge-to-Edge Repair Study (EVEREST I), acute procedural success was achieved in 19. In three others, the clip was placed but FMR wasn't significantly reduced, while one patient required bailout emergent cardiac surgery for pericardial effusion related to a transseptal complication. Two patients required transfusions of two units or more.
Twelve patients have completed 1 year of follow-up. Nine of the 12 continued to experience significant improvement at 1 year, compared with baseline, with only mild FMR and New York Heart Association functional class I or II status. Two patients were unchanged, compared with baseline, and one was worse, according to Dr. Hermiller of St. Vincent Heart Center, Indianapolis, who has received research grants from Evalve Inc., maker of the MitraClip.
Indicators of left ventricular (LV) remodeling provided important objective evidence of benefit, he added. The mean LV end diastolic dimension dropped from 6.0 cm at baseline to 5.4 cm at 12 months. The LV end systolic dimension decreased from 4.5 cm to 4.0 cm. And LV end diastolic volume fell from 208 mL to 178 mL.
Reaction to EVEREST I split along specialty lines. Interventional cardiologists called the early results impressive, with the caveat that the number of patients was small and follow-up was too brief to assess durability. But the potential applicability could be huge. Although the MitraClip was initially developed to address degenerative mitral regurgitation (MR), it's estimated that 60% of the 250,000 patients diagnosed with MR per year in the United States have FMR without degenerative structural changes—and the notion of treating them without resorting to open-chest surgery is highly attractive.
On the other hand, discussant Dr. Todd Rosengart, a cardiothoracic surgeon at Stony Brook (N.Y.) University, said their early experience with minimally invasive surgical repair of MR in 40 patients has been zero in-hospital mortality; a 2.5% rate of major morbidity at 30 days; a 1-day shorter length of stay than with open surgery; and a total operating room time of about 3 hours, similar to open surgery. But the percutaneous procedure has a major shortcoming: It aims to bring about functional recovery and improvement in FMR at the cost of destroying the integrity of the mitral structure, whereas surgical repair preserves structural integrity.