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SAN DIEGO -- It's common for prosthesis-patient mismatch to occur after transcatheter aortic valve replacement (TAVR) and this phenomenon is linked to worse outcomes, researchers reported.

Commercial TAVR procedures recorded in the Society of Thoracic Surgeons/American College of Cardiology Transcatheter Valve Therapy (TVT) Registry showed that patients developed severe and moderate prosthesis-patient mismatch -- in which a valve prosthesis's hemodynamics aren't appropriate for the patient's cardiac output requirement -- in 12% and 25% of cases, respectively, according to presenter Howard Herrmann, MD, of the University of Pennsylvania in Philadelphia.

Severe prosthesis-patient mismatch in particular was associated with some worse 1-year outcomes, he told the audience in a late-breaking trial session at the (TCT) conference:

• Mortality (17.2% versus 15.8% for peers with moderate or no mismatch, HR 1.19, 95% CI 1.09-1.31)
• Heart failure rehospitalization (14.7% versus 12.2%, HR 1.12, 95% CI 1.02-1.24)
• Death or heart failure rehospitalization (26.8% versus 24.2%, HR 1.13, 95% CI 1.06-1.22)

But neither stroke nor quality of life appeared to be affected by severe mismatch, however.

This is the largest study to date on this topic, according to Herrmann; findings were simultaneously published online in the Journal of the American College of Cardiology.

"We've known for a long time from the surgical literature that severe prosthesis-patient mismatch is certainly an issue that affects outcomes but it's been less clear in the TAVR literature," commented panelist Martin Leon, MD, of New York-Presbyterian/Columbia University Medical Center in New York City.

"I'm certainly not surprised by some of these outcomes but would have expected quality of life would also be affected," Leon said during a TCT press conference. "It's hard to say from the TVT Registry how robust some of this is."

The study included TVT Registry enrollees 65 years or older who had linkable Medicare claims (n=62,125). This was a cohort that had gotten TAVR in 2014-2017.

Prosthesis-patient mismatch was classified according to effective valve orifice area indexed to body surface area: severe (<0.65 cm²/m²), moderate (0.65-0.85 cm²/m²), or none (>0.85 cm²/m²).

Severe mismatch was tied to several prosthesis and patient factors -- the strongest being:

• Valve-in-valve procedure: OR 2.775, 95% CI 2.530-3.043
• Small prosthesis (diameter 23 mm or smaller): OR 2.773, 95% CI 2.588-2.971
• Larger body surface area: OR 1.710 per 0.2-unit increase, 95% CI 1.656-1.765
• Female sex: OR 1.463, 95% CI 1.353-1.583

The findings allow heart teams to discuss options for avoiding prosthesis-patient mismatch, such as the size or type of prosthesis that should be used during TAVR, Herrmann said at the press conference.

Type of device is important and the current literature on mismatch warrants looking at the different valves very closely -- especially self-expanding ones, suggested panelist Rebecca Hahn, MD, also of New York-Presbyterian/Columbia University Medical Center, during the main trial session.

Fellow session discussant Mayra Guerrero, MD, of Evanston Hospital in Illinois, posed the question: "Does this mean with smaller valves we need to be checking gradients ... and optimizing the gradient before the patient leaves?"

Gradients need to be optimized "for sure," responded Herrmann, but he emphasized that change in procedure should be upfront (not afterward with post-dilatation) given the knowable factors that predict the risk of prosthesis-patient mismatch.

"We have to plan for that," he said, adding that this can mean placing the device high, using fracture in valve-in-valve procedures, or even considering surgery.

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