Transcatheter Aortic Valve Implantation (TAVI) has transformed the treatment landscape for patients suffering from severe aortic stenosis, especially those considered high-risk or unsuitable for open-heart surgery. As TAVI becomes increasingly common among younger and lower-risk patients, long-term valve performance and complications are receiving greater attention. One important complication is prosthesis–patient mismatch (PPM), a condition where the implanted heart valve is too small relative to the patient’s body size.
A recent study published in Medicina explored the incidence, clinical characteristics, and outcomes of severe PPM in patients undergoing TAVI with large aortic annuli. The findings provide valuable insights into how PPM affects this specific patient population.
What Is Prosthesis–Patient Mismatch?
PPM occurs when the effective orifice area of the implanted prosthetic valve is too small for the patient’s body surface area. As a result, blood flow through the valve remains restricted even after valve replacement. According to the Valve Academic Research Consortium (VARC-3) criteria, severe PPM is defined by a significantly reduced indexed effective orifice area (iEOA).
PPM has been associated with poorer hemodynamic performance, reduced cardiac output, increased heart failure risk, and potentially higher long-term mortality after valve replacement procedures.
Study Overview
The study analyzed 353 patients with severe symptomatic aortic stenosis and large aortic annuli who underwent TAVI at Freeman Hospital in the United Kingdom between 2020 and 2024. Researchers retrospectively evaluated post-procedural echocardiographic data and patient outcomes over an average follow-up period of 35 months.
The primary objective was to determine:
- How common severe PPM is in patients with large aortic annuli
- Which patients are more likely to develop PPM
- Whether severe PPM influences long-term mortality
Key Findings
- Severe PPM Was Relatively Common
The study found that:
- 38% of patients developed some degree of PPM
- 15% developed severe PPM
These findings challenge the assumption that patients with larger aortic annuli are naturally protected against valve mismatch.
- Balloon-Expandable Valves Were More Frequently Associated with PPM
Patients who received balloon-expandable valves (BEV) experienced higher rates of both moderate and severe PPM compared with those receiving self-expanding valves (SEV).
The researchers suggested that valve design and leaflet motion restrictions in certain BEV systems may contribute to reduced valve opening and smaller effective orifice areas.
- Younger Patients with Larger Body Surface Area Were More at Risk
Patients who developed severe PPM were generally:
- Younger
- Larger in body surface area
- More likely to receive smaller valve sizes
This indicates that body size plays a major role in determining post-TAVI valve performance.
Hemodynamic Impact of Severe PPM
Although mortality differences were not statistically significant, patients with severe PPM demonstrated worse hemodynamic outcomes after TAVI, including:
- Lower stroke volume
- Reduced cardiac output
- Lower cardiac index
These findings suggest that severe PPM may negatively affect heart function and quality of life, even if short-term survival remains similar.
Did Severe PPM Affect Mortality?
At nearly three years of follow-up, mortality was numerically higher in patients with severe PPM (46% vs. 36%), but the difference did not reach statistical significance.
Researchers emphasized that the follow-up duration may have been too short to fully detect the long-term effects of PPM. Previous studies have shown that survival differences often become more apparent after three years.
Interestingly, body surface area appeared to influence outcomes. Patients with smaller body surface area who developed severe PPM had significantly higher mortality compared to those without PPM.
Clinical Implications
This study highlights several important considerations for cardiologists and heart teams:
- Large annuli do not eliminate the risk of severe PPM
- Valve selection matters when planning TAVI procedures
- Careful imaging and procedural planning are essential
- Long-term monitoring remains important, especially in younger patients
The findings also support continued innovation in transcatheter heart valve design to improve valve hemodynamics and reduce mismatch risk.
Conclusion
Severe prosthesis–patient mismatch remains a clinically relevant issue even in patients with large aortic annuli undergoing TAVI. While severe PPM did not significantly increase mortality within three years, it was associated with poorer hemodynamic performance and may affect long-term outcomes.
As TAVI expands into younger and lower-risk populations, optimizing valve sizing, improving prosthesis design, and understanding patient-specific risk factors will become increasingly important for achieving the best clinical outcomes.
References
- Mohamed Ali et al. “Incidence, Clinical Characteristics and Outcomes of Severe Prosthesis–Patient Mismatch in Patients Undergoing TAVI with Large Aortic Annuli.” Medicina, 2026, 62(5), 892.
- Philippe Pibarot & Marie-Annick Clavel. “Prosthesis-Patient Mismatch After Transcatheter Aortic Valve Replacement: It Is Neither Rare Nor Benign.” Journal of the American College of Cardiology, 2018.
- Valve Academic Research Consortium. VARC-3 Updated Endpoint Definitions for Aortic Valve Clinical Research, 2021.
