The evolution of scientific evidence over the past decade in comparative studies on transcatheter aortic valve implantation (TAVI) and aortic valve replacement (AVR) has been directed towards reducing surgical risk for patients included in such studies. Early on, the PARTNER IB study, comparing TAVI in inoperable patients due to prohibitive surgical risk with medical treatment, established the clinical benefit of the interventional strategy over conservative management. The PARTNER IA study, which compared TAVI to AVR in high-surgical-risk patients, demonstrated TAVI’s non-inferiority in terms of survival when compared to the, at that time, gold-standard technique.

The positive outcomes and technological advancements have supported a gradual expansion of TAVI indications, resulting in an increased number of candidates for the procedure. Consequently, Heart Team practices have shifted to selecting candidates with progressively lower surgical risk profiles than those for whom the procedure was originally intended. Given the high cost associated with the procedure, there is a need to optimize aspects such as efficiency, cost-effectiveness, and the avoidance of futility. This “TAVI phenomenon” has led to a significant reduction in AVR procedures, which has prompted surgical teams to re-evaluate patients whose intervention would have previously been deemed questionable due to their high theoretical risk, according to conventional scores (EuroSCORE II and STS-PROM score).

This paper reports a single-center case-control study (Southampton, UK), which retrospectively compared outcomes of high-surgical-risk patients for AVR, evaluated and rejected in a multidisciplinary session for TAVI between 2009 and 2019. Among 1095 high-surgical-risk patients assessed, TAVI was denied to 519. Of these, 114 (10.4%) were re-evaluated and selected for AVR, while the remaining 405 (37%) were managed conservatively.

Upon referral of candidate cases to the reference center, initial assessment was performed by a surgeon who determined the surgical risk. High/prohibitive risk patients were then evaluated in a multidisciplinary session for TAVI. Reasons for rejection included technical aspects that made the procedure prohibitive (vascular access, dilated roots, large annulus, low coronary ostia, calcified mitral annulus, and severe ventricular hypertrophy) and patient-related clinical factors (significant comorbidities being the primary cause for rejection; lack of consent; or minimal/absence of symptoms). Although the authors did not detail morbidities among patients rescued with AVR versus those treated conservatively, it is expected that the latter group had higher comorbidity, which may have impacted follow-up mortality. The mean age was 80 years, with an average logistic EuroSCORE of 8. Additional procedures to AVR were performed in 15.7% of cases, mainly coronary revascularization. Hospital mortality in the AVR group was 2.2% (below the predicted high surgical risk, >8-10%), and the stroke rate was 4.4%. Five-year survival was 12.6% for the conservative management group versus 59.5% in the AVR group (p < 0.001). AVR acted as an independent protective factor (HR = 0.37; p < 0.001), with fewer hospital readmissions compared to the conservative management group (13.6 episodes/patient-year vs. 6.9 episodes/patient-year; p = 0.002).

The authors conclude that AVR can be considered in elderly, high-surgical-risk patients rejected for TAVI in centers with low operative mortality, as AVR may outperform conservative treatment in well-selected patients.

COMMENTARY:

Despite the study’s limitations, an important message emerges: the selection criteria for candidates with severe aortic stenosis for AVR or TAVI remain imprecise, preventing perfect procedure matching for each patient. In daily practice, this is exemplified by cases like a patient indicated for multiple combined procedures who is accepted for surgery. While another over 75 years old with isolated severe aortic stenosis and low surgical risk is selected for TAVI, or multiple successful cases of TAVI explants subjected to AVR initially denied.

The outcomes in this surgical group, despite consisting of highly comorbid octogenarians, are noteworthy for their success in both the perioperative phase and follow-up. The superiority of the surgical group over conservative management, while this may seem like a turn of tables of PARTNER IB, it should not be viewed as such since these patients are likely not comparable. However, the high mortality in the conservative management group reinforces the need to continue focusing on these patients as, with appropriate selection, a two-thirds reduction in mortality and a significant improvement in quality of life can be achieved.

The evidence supporting current and future clinical guideline recommendations remains biased by selection criteria in sample populations, operators, and participating centers, which diverges from real-world practice. Hence, attention to registry-reported outcomes may offer a more practical strategy for managing severe aortic stenosis patients. Furthermore, beyond registry data, the active participation of surgical teams in Heart Team decision-making, tailored for each patient, remains the best assurance for assigning the optimal treatment option, suited to each phase of the disease and each center’s capabilities, under the necessary outcome audit by teams conducting each procedure. Neither age (a reference parameter in recent clinical guidelines, albeit arbitrary) nor predicted surgical risk (often overestimated in available scores; risk factors not considered in these scores; lack of generalization in using TAVI-specific risk scores that could be compared with surgical-specific ones) continue to serve as adequate criteria for assigning patients to one alternative or another. Therefore, multidisciplinary assessment remains essential, as does the active participation of the cardiac surgeon. With the need to incorporate surgeons into transcatheter techniques, as they possess the full technical arsenal to offer the best therapeutic option for each patient, their opinion must be considered.

REFERENCE:

Luthra S, Leiva-Juarez MM, Malvindi PG, Navaratanaraja M, Curzen N, Ohri SK. Reconsidered surgical aortic valve replacement after declined transcatheter valve implantation. Asian Cardiovasc Thorac Ann. 2022 Nov;30(9):1001-1009. doi: 10.1177/02184923221132202.