Patient-Prosthesis Mismatch Common in TAVR, Survival Suffers

Patrice Wendling

September 25, 2018

SAN DIEGO — Severe prosthesis–patient mismatch (PPM) occurs in more than 10% of patients after transcatheter aortic valve replacement (TAVR) and increases the risk for death but not stroke, according to the largest study to date.

"We've identified a problem and I think the awareness is really the first step in trying to fix it," study author Howard C. Herrmann, MD, Perelman School of Medicine, University of Pennsylvania, Philadelphia, told | Medscape Cardiology. "We spend a lot of time in heart team meetings looking at CT scans for annular dimensions, their vascular access, but we don't really talk too much about severe PPM or the risk of that."

"I think this allows us to start calculating that, to predict it based on patients' factors and what prosthesis we might be choosing for a patient," and "to think about alternatives."

Herrmann reported the late-breaking results here at Transcatheter Cardiovascular Therapeutics 2018 to coincide with its publication September 23 in the Journal of the American College of Cardiology.

Surgeons have known for decades about the link between worse outcomes and PPM, which occurs when the effective orifice area (EOA) of the prosthesis is too small in relation to the patient's body size, resulting in high transvalvular pressure gradients.

Although TAVR results in a larger EOA than surgical aortic valve replacement, less is known about the association between PPM and TAVR outcomes because only small series or limited follow-up are available, Herrmann said.

Using the Society of Thoracic Surgeons/American College of Cardiology Transcatheter Valve Therapy (TVT) Registry, investigators identified 62,125 patients who underwent commercial TAVR from January 2014 to March 2017, and linked 37,470 patients 65 years of age at the time of treatment to Medicare administrative claims data.

PPM was classified according to EOA measured by echocardiography at hospital discharge and indexed to body surface area (EOAI) as severe (<0.65 cm²/m²), moderate (0.65 - 0.85 cm²/m²), and none (>0.85 cm²/m²).

Severe and moderate cases of PPM were present in 12.1% and 24.6% of patients, respectively.

Patients with severe PPM were younger, more likely to be African American, and to have a lower ejection fraction and higher body surface area. Mean aortic gradient was 42.8 mm Hg in patients with severe PPM and 43.2 mm Hg in those with moderate PPM or no PPM. The use of valve prosthesis 23 mm or smaller in diameter was 40.0%, 32.1% and 24.0%, respectively.

On multivariate regression analysis, predictors of severe PPM with the highest odds ratios (OR) were a valve prosthesis of 23 mm or smaller (OR, 2.8; P < .001) and valve-in-valve procedure (OR, 2.8; P < .001), Herrmann reported.

Other significant predictors included female sex (OR, 1.5), being 75 years or younger (OR, 1.03 per 5-year decrease), being nonwhite/Hispanic race (OR, 1.23), having a higher body surface area (OR, 1.7 per 0.2 unit increase), having a lower ejection fraction (OR, 1.09 per 5% decrease), and having atrial fibrillation (OR, 1.11), severe mitral regurgitation (OR, 1.07), or severe tricuspid regurgitation (OR, 1.09).

At 1 year, risk for death was higher for patients with severe PPM than for those with moderate or no PPM (17.2% vs 15.8%; adjusted hazard ratio [HR], 1.19; P < .001), as were risk for heart failure rehospitalization (14.7% vs 12.2%; HR, 1.12; = .017) and risk for death or heart failure rehospitalization (26.8% vs 24.2%; HR 1.13; P < .001).

No association was found between severe PPM and stroke (3.8% vs 4.2%; HR, 0.98; = .798) or quality of life, as measured by the Kansas City Cardiomyopathy Questionnaire.

It's possible that EOAI measurements at discharge can be influenced by periprocedural issues and might be more accurate if obtained later; however, a separate analysis of 30-day survivors did not suggest an effect on the conclusions, Herrmann said. Further, the EOAI values are consistent with previous studies and more accurate than those obtained by projection or geometric measurement.

During discussion of the results, panelists remarked on the lack of postdilatation data and of data comparing balloon-expanding and self-expanding valves. Self-expanding valves, Herrmann said, have been shown in several studies to have a slightly larger EOA, particularly in the small annular dimensions.

"That might be a consideration as we think about how to avoid this problem," he said.

Rebecca T. Hahn, MD, New York–Presbyterian/Columbia University Medical School in New York City, pointed out that a recent study she was involved in, which looked at Echocardiography Core Lab measurements from randomized trials, showed similar 1-year mortality rates of 21% for severe PPM and 12% for lower or no PPM with the self-expanding CoreValves.

However, she said, there was no association between mortality and PPM in either the PARTNER 2 or PARTNER SAPIEN 3 trials and, in fact, 1-year mortality for any grade of PPM is significantly lower at 5% to 8%, respectively.

"So despite what I published, I do think that you need to understand that the literature on PPM warrants looking at the different valves very, very closely, since the only mortality signal was with the CoreValve," Hahn said.

Herrmann noted that several other nonrandomized trials, albeit small, have suggested PPM does have an effect on outcomes.

"The problem with the PARTNER trial, of course, is that the numbers are small," he added. "You're talking about roughly 300 to 600 patients who were studied in that, compared with the 60,000 we were able to look at. So the number of patients who truly had severe PPM is quite small and there were trends in the direction of adverse outcomes."

When interviewed, Herrmann said, "There are alternatives to try to avoid PPM — everything from which prosthesis we choose, the size of the prosthesis, to whether we fracture a patient's valve if we are doing a valve-in-valve procedure. And in the future, even in some situations we might choose in low-risk patients or a low–intermediate risk patient, surgery, an enlargement operation, in order to get a larger effective orifice area."

"I think there are choices that we can make and we need to start thinking about that in the heart team approach," he added.

Commenting for | Medscape Cardiology, Hadley Wilson, MD, Sanger Heart & Vascular Institute, Charlotte, North Carolina, said, "We need to be more attentive to echocardiographic parameters, including the effective valve orifice area. And we need to look at 3D imaging to see if that is helpful, and other modalities, like CT imaging, to predict the ideal TAVR size valve to put in these patients to try to avoid these mismatches."

Herrmann reports institutional research funding from Abbott Vascular, Bayer, Boston Scientific, Corvia, Edwards Lifesciences, Medtronic, and St. Jude Medical, and consulting fees/honoraria from Edwards Lifesciences, Medtronic, and Siemens Healthineers.

Transcatheter Cardiovascular Therapeutics (TCT) 2018. Presented September 23, 2018.

J Am Coll Cardiol. Published online September 23, 2018. Abstract

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