MitraClip Benefits High-, Prohibitive-Risk Patients with Mitral Regurgitation

 Download this article's Factoids (Factoid 1, Factoid 2) (PDF & PPT for Gold Subscribers)

 

Transcatheter mitral valve repair improves both hemodynamics and symptoms at 1 year in patients with severe mitral regurgitation (MR) who are at either high or prohibitive risk for surgery, according to a pair of registry studies published in the July 15, 2014, issue of the Journal of the American College of Cardiology

Evaluating High-Risk Patients  

Methods
In the high-risk study, investigators led by Donald D. Glower, MD, of Duke University Medical Center (Durham, NC), analyzed outcomes of 351 patients with symptomatic, severe MR (grades 3 to 4+) who underwent mitral valve repair with MitraClip (Abbott Vascular; Santa Clara, CA). The patients, drawn from the EVEREST II High Risk Registry (n = 78) and the REALISM continued access registry (n = 273), were at high risk for surgery, based on a Society of Thoracic Surgeons (STS) score of at least 12% (43.0%) or the opinion of the surgeon co-investigator. 
Average age was 76 years, and most patients presented with functional MR (70.1%). The majority had a history of CHF (98.0%) and CAD (82.2%).  

MitraClip was not implanted in 15 patients (4.3%). At discharge, 84.6% of patients achieved at least 1 grade reduction in MR and 85.8% were reduced to grade 2+ or lower. Mean hospital stay was 3.2 days, and most patients (91.7%) were discharged home.

There were no cases of device embolization. Single-leaflet attachment occurred in 8 patients, and in 6 of the 7 secondary interventions, MR was reduced to 2+ or lower. Mitral stenosis occurred in only 1 patient and did not require reintervention. 

None of the 17 deaths (4.8%) that occurred in the first 30 days was due to device malfunction, and the 97.5% upper confidence boundary of 7.6% was lower than the predicted STS mortality rate. Most of the 9 strokes (2.6%) occurred in older, higher-risk patients. The most common event was transfusion of more than 2 units of blood (13.4%). The overall rate of major vascular complications was 3.4%, consisting of 4 hematomas, 5 access site repairs, and 3 arteriovenous fistulas. Few additional complications occurred between 30 days and 1 year. 

At 1 year, the procedure was markedly effective in reducing MR grade to 2+ or lower and improving functional metrics including quality of life and LV hemodynamics; only LVEF remained unchanged (table 1).

Table 1. Efficacy at 1 Year

 

Baseline

1 Year

P Value

MR Grade ≤ 2+

14.2%

83.6%

< .0001

NYHA Class III-IV

82.1%

17.1%

< .0001

SF-36 QoL

    Physical Score

    Mental Score

 

34.0 ± 9.1

44.9 ± 13.5

 

38.8 ± 11.3

49.8 ± 12.2

 

< .0001

< .0001

LV End-Diastolic Volume, mL

160.5 ± 55.9

142.6 ± 53.1

< .0001

LV End-Systolic Volume, mL

87.0 ± 46.8

78.9 ± 43.9

< .0001

LVEF

48.4%

47.5%

.16


Efficacy in Patients Designated ‘Prohibitive Risk’

Methods
For the prohibitive-risk study, D. Scott Lim, MD, of the University of Virginia (Charlottesville, VA), and colleagues analyzed outcomes of 127 patients with severe MR from the above registries who were retrospectively determined to be at prohibitive risk for surgery. The designation required the presence of 1 or more documented surgical risk factors including an STS score of at least 8% or factors not included in the STS risk calculator such as porcelain aorta, hostile chest, and frailty.  


Device implantation was successful in all but 6 patients (4.7%). There were no reports of device embolization or single leaflet attachment. Mean hospital stay was 2.9 days, and most patients (88%) were discharged home.

At 30 days, the mortality rate was much lower than the mean STS-predicted surgical mortality rate of 13.2%. Six of the 8 deaths were cardiac-related, of which 1 arose from a prolonged procedure. According to the authors, other events out to 1 year were consistent with the safety profile seen in EVEREST II (table 2).

Table 2. Safety Outcomes at 30 Days and 1 Year

 

30 Days

1 Year

Death

6.3%

23.6%

Major Bleeding Complications

12.6%

15.7%

Stroke

2.4%

2.4%

Major Vascular Complications

5.5%

7.1%


Improvement to MR grade 2+ or lower was seen in 86.1% of patients with a baseline grade of 3+ and 68.4% of those with a baseline grade of 4+. Of 91 patients discharged with an MR grade no higher than 2+, 70.3% sustained that level at 1 year, while 11.0% worsened and 18.7% died. Kaplan-Meier estimates of 1-year survival were similar for patients with discharge MR grade 1+ or lower and 2+ (83.3% and 80.0%, respectively), and both surpassed estimated survival for patients with grades 3+/4+ (52.4%).

Moreover, of 98 patients in NYHA functional class III/IV at baseline, almost one-third (30.6%) improved by at least 2 classes. At 1 and 12 months, the mean SF-36 quality-of-life mental and physical component scores, which were depressed at baseline, approximated norms for older adults.

LV end-diastolic volume decreased from 125.1 ± 40.1 mL at baseline to 108.5 ± 37.9 mL at 12 months (P < .0001), while LV end-systolic volume showed a favorable trend (P = .07).

 ‘Separate’ Diseases?

In an accompanying editorial, Blase A. Carabello, MD, of Mt. Sinai Beth Israel (New York, NY), observes that degenerative and functional MR are “nearly separate diseases.” In degenerative disease, mitral valve repair can maintain LV function and restore a normal life expectancy, but given the low rates of surgical repair in the real world, MitraClip is a potential alternative, he says. On the other hand, for functional MR, where there is no proof that surgery prolongs life, the less invasive endovascular therapy “would appear to be ideal” because in very ill patients it improves quality of life.

“In the future, to fully understand the role of percutaneous MR repair, we must study it separately in the 2 very different diseases for which it is being applied, so we can define its role in [degenerative] versus [functional] MR,” Dr. Carabello asserts.

Threshold Effect of MR Reduction

In a telephone interview with TCTMD, Ted Feldman, MD, of Evanston Hospital (Evanston, IL), a coauthor of both studies, countered, “Every retrospective analysis… looking at outcomes in the degenerative vs functional mitral regurgitation high-risk patients doesn’t show a lot of difference.” 

Dr. Feldman observed that, contrary to the predictions of many surgeons who typically achieve very low levels of residual MR, in all the endovascular trials, patients whose grades were reduced to at least 2+ did very well. In the latest report from the randomized EVEREST II trial, those patients had stable outcomes out to 5 years, he added. 

Moreover, during the registries, experience with the endovascular procedure underwent a learning curve, Dr. Feldman noted. For example, the acute success rate went from the 80-85% range at the beginning to over 90% at the end, and now in international practice it has reached 95%, he reported. In addition, the incidence of the device losing hold of a leaflet within the first 30 days has declined from 10% in EVEREST I to about 1% today. “And though it is hard to measure, I think we’ve gotten better at patient selection,” he added.

The bottom line of all the MitraClip studies, Dr. Feldman said, is that now there is an option for a large group of patients who previously had none. “At the least it makes them feel better and appears to keep them out of the hospital,” he said. In international practice, both high- and prohibitive-risk patients are being treated, while in the United States prohibitive-risk patients with degenerative mitral disease are eligible, and “we’re working on trials for the functionals,” he said, alluding to the large ongoing COAPT trial.

Note: William A. Gray, MD, who co-authored the prohibitive-risk study, is a faculty member of the Cardiovascular Research Foundation, which owns and operates TCTMD.



Sources:

1. Glower DD, Kar S, Trento A, et al. Percutaneous mitral valve repair for mitral regurgitation in high-risk patients: results of the EVEREST II study. J Am Coll Cardiol. 2014;64:172-181.

2. Lim DS, Reynolds MR, Feldman T, et al. Improved functional status and quality of life in prohibitive surgical risk patients with degenerative mitral regurgitation after transcatheter mitral valve repair. J Am Coll Cardiol. 2014;64:182-192.

3. Carabello BA. Treatment for mitral regurgitation: which one are we talking about [editorial]? J Am Coll Cardiol. 2014;64:193-195.

Related Stories:

Disclosures
  • Dr. Lim reports serving as a consultant to and receiving research grants from Abbott.
  • Drs. Glower and Carabello report no relevant conflicts of interest.
  • Dr. Feldman reports serving as a consultant to and receiving honoraria or institutional research support from Abbott, Boston Scientific, Edwards Lifesciences, and WL Gore.

We Recommend

Comments