Echocardiographic Variables Predict Failure of MitraClip Procedures

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Variables related to the degree of either mitral regurgitation (MR) or mitral stenosis can serve as predictors of overall procedural failure when selecting high-risk patients for MitraClip implantation, according to a study published online March 19, 2014, ahead of print in JACC: Cardiovascular Interventions.

Researchers led by Volker Rudolph, MD, of Uniklinik Köln (Cologne, Germany), examined acute procedural outcomes in 300 consecutive elderly patients at high surgical risk who underwent percutaneous mitral valve repair at their institution using the MitraClip device (Abbott Vascular, Santa Clara, CA) from September 2008 to April 2012.

A left ventricular end systolic diameter > 55 mm and a mitral valve orifice area (MVOA) < 4.0 cm², were met by 39% and 57% of patients, respectively. Failure to meet either of these served as exclusion criteria for MitraClip therapy in the EVEREST II study.

Orifice Area, Pressure Gradient Predictive

The rate of acute procedural success was 89.3%, and a single clip was used in 66% of patients. Median device time (ie, time from transseptal puncture to withdrawal of the clip delivery system from the left atrium) was 63 minutes in successfully treated patients. The primary causes of procedural failure were failure to reduce MR severity to grade ≤ 2+ despite clip implantation (clip failures) and failure to implant a clip (aborted procedures).

When successful procedures (n = 268) were compared with failed procedures (n = 32), MR etiology, effective regurgitant orifice area (EROA), transmitral pressure gradient (TMPG), and mitral valve orifice area (MVOA) emerged as univariate predictors of procedural failure. However, on multivariate logistic regression, only EROA and TMPG remained independently predictive of overall procedural failure (table 1).

Table 1. Independent Predictors of Procedural Failure vs Success

 
On classification tree analysis, EROA > 70.8 mm² was associated with 25% of clip failures, whereas the combination of an MVOA ≤ 3.0 cm² and a TMPG ≥ 4 mm Hg was associated with 37.5% of aborted procedures. Of the 7 total clip failure patients, 5 (71%) had degenerative/mixed origin MR with a flail leaflet being responsible for the high EROA in 4 of the 5.

Logistic regression analysis validated the classification tree analysis by showing that an EROA > 70.8 mm² (OR 5.54; 95% CI 1.80-16.3) and a TMPG ≥ 4 mm Hg (OR 3.08; 95% CI 1.04-8.75) were independently predictive of clip failure, whereas an MVOA ≤ 3.0 cm² (OR 0.19; 95% CI 0.04-0.82) and a TMPG ≥ 4 mm Hg (OR 11.0; 95% CI 2.7-61.8) were independently predictive of an aborted procedure.

The overall success rate in patients with an EROA > 70.8 mm² and an MVOA ≤ 3.0 cm² was 80%. However, the combination of TMPG ≥ 4 mm Hg and an MVOA ≤ 3.0 cm² yielded the lowest success rate of all subgroups (56.3%). When TMPG was ≤ 3 mm Hg in the presence of an MVOA ≤ 3.0 cm², the success rate was 89.7%.

Additionally, procedural failures were more frequent in patients with degenerative/mixed origin MR than those with MR of functional etiology. However, there was no difference between the 2 groups with regard to the distribution of the type of procedural failure (clip failure vs aborted procedure).

Examination of Procedural Failure Predictors Necessary

“Our data thus do not indicate that the higher risk of procedural failure in [degenerative/mixed origin MR] patients should be taken as an argument against MitraClip therapy in these patients,” the study authors write. “Instead, our data advocate that variables predictive of procedural failure, such as those presented in this study, should be assessed regardless of MR etiology to possibly reduce procedural failure rates further and obtain durable MR reduction.”

Dr. Rudolph and colleagues suggest that the variables identified in the study as predictive of failure have practical application for clinicians. For example, patients identified as having the combination of an EROA ≤ 70.8 mm² and an MVOA > 3.0 cm² have a high chance of a technically successful procedure. In contrast, those with untoward morphology require more critical evaluation for suitability of MitraClip therapy.

Findings Validate, Refine Anatomic Criteria

In an email with TCTMD, Ted Feldman, MD, of Evanston Hospital (Evanston, IL), said while most patients in the study did not meet the EVEREST II anatomic criteria, “those were developed before there was any significant experience with the device, so this analysis does a lot to help validate some of the principles of the criteria.”

For example, Dr. Feldman said the data better defined the lower end of acceptable baseline MVOA.

“It is clear that the EVEREST II (and COAPT) trial exclusion of 4 cm² is not an absolute in practice,” he said. “This paper makes it clear that 3 cm² is too small at baseline, which is helpful. Whether 3.5 cm² or slightly higher is a better value remains to be defined.”

Additionally, Dr. Feldman said the finding that EROA is a predictor of overall procedural failure better quantifies the EVEREST II criteria of “large flail gap and flail width,” especially since this was noted mostly in patients with degenerative/mixed origin MR.

“It would be interesting to see if these [degenerative/mixed origin MR] clip-failure cases had echo morphologic features associated with multiple chordal or primary chordal rupture associated with the larger EROA,” he concluded.

Study Details

The mean age of patients was 75 years and median logistic EuroSCORE was 24%. There was a high rate of comorbidities such as renal failure (55%), A-fib (65%), and CAD (66%). The majority of patients (68%) had MR of functional etiology.

 

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Source:
Lubos E, Schlüter M, Vettorazzi E, et al. MitraClip therapy in surgical high-risk patients: identification of echocardiographic variables affecting acute procedural outcome. J Am Coll Cardiol Intv. 2014;Epub ahead of print.

 

• Dr. Feldman reports receiving research grants from and serving as a consultant to Abbott and Boston Scientific.

 

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