Prosthesis-patient mismatch in patients undergoing transcatheter aortic valve replacement

Selected in European Heart Journal by L. Biasco , C. Cook

This joint review is part of the PCRonline GLOBAL Journal Club Initiative by selected members of the EAPCI/PCR Journal Club and PCR NextGen, and is based on the underlying idea of “Bringing peers together, exchanging ideas, towards a common standard of care”.

Reviewers

Luigi Biasco

@BiascoDr

Interventional cardiologist / Cardiologist

OSPEDALE CIRIÈ - Ciriè, Italy

Christopher Cook

@CCook_MD

Interventional cardiologist / Cardiologist

The Essex Cardiothoracic Centre - Basildon, United Kingdom

Our Comment

Why this study – the rationale/objective?

Prosthesis-patient mismatch (PPM) represents an unbalance between the hemodynamics of a valve prosthesis and the specific patient’s requirements for cardiac output. It is classified on the basis of the effective valve orifice area indexed (EOAI) to body surface area (BSA) and considered to be absent or not clinically significant when the indexed EOAI is >0.85 cm2/m2, moderate when between 0.65 and 0.85 cm2/m2, and severe when <0.65 cm2/m2.
The incidence of PPM after surgical aortic valve replacement can be as high as 40%. PPM can negatively impact functional status, exercise tolerance, late structural valve deterioration and long term prognosis.
The incidence and impact of PPM post transcatheter aortic valve replacement (TAVR) are largely unknown. The objective of this study presented was to determine the incidence, predictors, and 1-year outcome of severe PPM in more than 60,000 patients treated with TAVR.

How was it executed – the methodology?

• Population: 62,125 patients treated with TAVR in the US between 2014 and 2017.
• Procedural and in-hospital outcomes defined according to the VARC classification obtained from registry data/postdischarge outcomes with 1-year follow-up obtained through Medicare administrative claims in 37,470 patients.
• Multivariate logistic regression model to identify predictors of severe PPM.
• Primary study outcomes: death, HF hospitalisation, death or HF, stroke, and the overall Kansas City Cardiomyopathy Questionnaire (KCCQ) score 1 year after TAVR analysed with unadjusted and adjusted Cox proportional models.

What is the main result?

• Severe PPM in 12%, moderate PPM in 24% of patients. Patients with severe PPM were on average younger than patients with no PPM.
• Independent predictors of PPM with strongest associations were: valve prosthesis diameter ≤23 mm, valve in valve procedure, larger BSA, female sex. Lower LVEF, younger age, non white/hispanic ethnicity, atrial fibrillation and severe mitral and tricuspid regurgitation were as well associated.
• Outcomes in severe PPM:
  • 30 days: higher rates of HF hospitalisation, stroke, and death as compared to moderate and no PPM.
  • 1 year: mortality 17.2% in severe, 15.6% in moderate and 15.9% no PPM (p=0.02) while HF hospitalisations 14.7% in severe,12.8% in moderate and 11.9% no PPM (p < 0.0001).

Critical reading and the relevance for clinical practice

The purpose of transcatheter aortic valve intervention is to optimise the hemodynamic conditions between the left ventricle and aorta. Prosthesis-patient mismatch, a well know phenomenon by surgeons, is evident in about 10% of cases and, when severe, is clearly associated with an almost 2 fold increase in mortality after surgical aortic valve replacement. In line with evidence derived from surgery, the paper by Dr Herrmann and coauthors clearly demonstrates that severe PPM is evident after TAVR in 12% of patients and is associated with 19% increase in the risk of mortality at one year as compared to no or moderate PPM.

Severe PPM was also associated with a reduced improvement of quality of life index (measured with KCCQ score) at 30 days and an increased incidence of hospitalisations for heart failure at one year, emphasizing that persistence of an imbalance between valve hemodynamics (either native or prosthetic) and patient’s functional requirements have an impact on symptoms and prognosis.

Authors recognised several factors associated with severe PPM. While some of them are intuitive such as valve diameter ≤23 mm and female sex, some other arouse reflections.

Interestingly, younger age and valve in valve procedures resulted as independent predictors of severe PPM after multivariable analysis. Those two findings, alone and considered as a whole, have several implications in clinical practice. The current trend in TAVR is to offer the procedure to progressively lower surgical risk candidates (i.e. more frequently younger patients). Concerns about valve durability of the implanted prosthesis are often rebuted by the possibility of a future VIV procedure. However, data presented in the present paper should at least represent a word of caution to this approach, that might, in selected cases, represent a double failure.

Some limitations of the paper should be mentioned. First, the lack of a core lab analysis of data used to determine the presence and grade of PPM. Second, the referral of patients to the registry was done on a voluntary basis by each site, introducing selection bias and potentially underestimating/overestimating the incidence of PPM. Third, the impact of PPM on prosthesis durability was beyond the scope of the current manuscript (an ongoing debate in TAVR in the younger patient population). Last, follow-up data were available in only ~60% of cases and were derived from administrative reports. Thus, intrinsic inaccuracies to the dataset apply.

Improving outcomes in TAVI patients:

The study of Herrmann et al provides important new data highly relevant to the TAVR field. Although the inherent limitations of registry-based data apply, the identification and quantification of the deleterious effect of PPM post-TAVI focus future efforts on minimising this phenomenon. As TAVR continues to expand into lower risk patient populations, long-term success in optimally matching the hemodynamics of a valve prosthesis and the specific patient’s requirements for cardiac output are paramount.