The indications for TAVI are rapidly expanding to include patients at lower surgical risk with extended life expectancy, making valvular hemodynamics increasingly relevant for this group.

PPM arises when the effective orifice area (EOA) of the prosthesis is insufficient relative to the patient’s body surface area (BSA). The adverse outcomes of PPM after surgical aortic valve replacement (SAVR) have been well-documented and were confirmed in a recent meta-analysis, indicating a significant 34% increase in mortality. PPM following TAVI, however, has been less studied, and existing data are inconsistent. The 2018 STS/ACC TAVR registry reported severe PPM in 12% of cases, associating it with increased one-year mortality and heart failure-related rehospitalizations. It is well-known that the Asian population generally has a significantly smaller aortic annulus than European counterparts, yet the incidence and clinical impact of PPM post-TAVI in this population remain largely unknown.

The objective of this study was to evaluate the EOA following TAVI using standardized assessment methods and to determine the midterm clinical impact of PPM post-TAVI with self-expanding CoreValve® or Evolut R® prostheses (Medtronic®) in an Asian population.

In a cohort of 201 consecutive patients who underwent TAVI, PPM incidence was assessed at 30 days, defined by indexed EOA as severe (<0.65 cm²/m²) or moderate (0.65–0.85 cm²/m²). Multivariable regression models examined predictors of PPM as well as mortality and heart failure rehospitalizations at midterm follow-up. Moderate and severe PPM were observed post-TAVI in 37 patients (18.4%) and 3 patients (1.5%), respectively, with these 40 patients comprising the PPM group. Predictors of PPM included female sex, larger BSA, and reduced left ventricular ejection fraction (LVEF). Over a midterm follow-up (median, 30.4 months), patients with PPM exhibited higher risks of all-cause mortality (HR, 1.95; p = 0.027), cardiovascular mortality (HR, 3.38; p = 0.043), and heart failure rehospitalization (HR, 2.40; p = 0.025).

The authors conclude that PPM is associated with increased mortality and rehospitalization rates for heart failure in the Asian population at midterm follow-up.

COMMENTARY:

This article, although a retrospective study, holds significance not only by demonstrating worse clinical outcomes in the PPM group post-TAVI but also as it does so for the first time in an Asian cohort with longer midterm follow-up than previous studies (30.4 months). Patients with larger BSA, reduced LVEF, and elevated transvalvular gradients were more likely to experience PPM. Notably, beyond the first year post-TAVI, PPM’s clinical impact on these patients subsides, suggesting that the repercussions of this condition are relatively early post-implantation.

Multiple studies and meta-analyses have shown a high incidence of PPM after SAVR, with a 30% increase in mortality. The STS/ACC TAVR registry, which includes over 60,000 patients, reported a PPM incidence of 37%, markedly higher than that observed in this study by Chen et al. This study reveals that PPM has a substantial clinical impact (mortality and rehospitalizations) on a TAVI patient cohort with a mean age of 80, raising concerns over its potential effect on patients 10–20 years younger.

Surgeons have tools available to reduce PPM risk by calculating the expected EOA for a prosthesis using various tables and/or applications, selecting the most appropriate prosthesis type and size for the patient. Although these industry-generated EOA tables are not flawless and have faced criticism, they may be indispensable for minimizing PPM incidence in certain patient subgroups. With the current evidence, largely supported by studies like Chen et al., there is a clear need for similar tables tailored for TAVI prostheses. Any clinician involved in TAVI should have access to such information, particularly as trials are underway to assess TAVI in younger, lower-risk patients.

It is time for multidisciplinary teams, especially when managing younger patients, to consider expected postprocedural EOA for each valve type and size to guide patient management decisions. Depending on individual cases, consideration must be given to TAVI and surgical prosthesis options, types and sizes (including mechanical valves that are less prone to PPM), and even potential aortic root enlargement techniques (such as Nicks or Manouguian procedures).

REFERENCE:

Chen YH, Chang HH, Kuo CC, Leu HB, Lin SM. Impact of Prosthesis-Patient Mismatch After Transcatheter Aortic Valve Replacement in Asian Patients. Ann Thorac Surg. 2022 Nov;114(5):1612-1619. doi: 10.1016/j.athoracsur.2021.09.016.