Currently, surgical aortic valve replacement (SVA) has been relegated by transcatheter aortic valve implantation (TAVI), which has become the recommended approach in clinical guidelines for specific cases of aortic stenosis. Surgery has clearly lost its primary role in treating these patients. We are even at the point of considering it only when percutaneous procedures are ruled out, a topic previously discussed in blog entries (Luthra S et al., Asian Cardiovasc Thorac Ann. 2022: “Second Chances: Salvaging Patients Rejected for Transcatheter Aortic Valve Implantation with Surgical Aortic Valve Replacement”).

This time, we present an article published in April of this year on the use of TAVI in a setting where surgery is still the standard of care: aortic insufficiency. The study analyzed a cohort selected from a U.S. health insurance database, aiming primarily to evaluate mid-term mortality.

According to a report from 2011–2014 by the Society of Thoracic Surgeons (STS) and the American College of Cardiology Transcatheter Valve Therapy (ACC TVT) registry, up to 40% of TAVI implants in the U.S. are indicated for patients with native aortic insufficiency. However, few studies have examined the safety and efficacy of percutaneous versus surgical treatment in this condition, and the results have been conflicting. Furthermore, the studies conducted to date suffer from numerous limitations, such as small sample sizes, retrospective designs, and short follow-up periods. Nevertheless, the study that inspires this commentary is one of the largest analyses of elective transfemoral TAVI outcomes for aortic insufficiency compared to SVA.

Patients included from January 2016 to December 2019 were identified using International Classification of Diseases (ICD) procedure codes and were enrolled in health insurance for at least one year before the intervention. Patients with a history of aortic stenosis, ventricular assist device implantation, aortic dissection, endocarditis, valve-in-valve procedures, and emergency cases were excluded. Additionally, for the TAVI group, all non-transfemoral approaches were excluded, and for the SVA group, patients with concomitant surgery on the mitral valve, aortic root, or ascending aorta were excluded. The primary endpoint was mortality at the longest available follow-up. Secondary endpoints included hospital mortality, 30-day and 1-year mortality, 30-day and 1-year stroke, and admission with a primary diagnosis of heart failure, endocarditis, stroke, or reintervention on the aortic valve. Acute kidney injury, atrial fibrillation (AF), transfusion requirements, need for permanent pacemaker implantation, and conversion to surgery in TAVI procedures were also analyzed. Mortality data was collected up to August 2020. Patients were censored upon disenrollment from insurance, upon experiencing an adverse event, or at the study’s end. Overlap propensity weighting and multivariable logistic regression and Cox proportional hazard models were used to adjust for confounders in analyzing the outcomes.

The final cohort included 11,027 patients from 345 centers, with 1,147 (10.4%) undergoing TAVI and 9,889 (89.6%) SVA. In terms of baseline characteristics, patients in the TAVI group had higher frailty scores (p < 0.001), a greater prevalence of bicuspid aortic valves (60.9% vs. 43.2%, p < 0.001), and 2% required concomitant percutaneous revascularization. The SVA group was younger on average (mean age: 72.9 ± 5.1 vs. 76.9 ± 7.1 years, p < 0.001), with fewer comorbidities, and underwent concurrent tricuspid valve surgery in 0.24% and coronary artery bypass grafting in 29.7% of cases.

At a median follow-up of 31 months (interquartile range: 18–44 months), the TAVI group showed higher all-cause mortality in both unadjusted and adjusted risk analyses (HR = 1.90; p < 0.001). There were no differences in in-hospital mortality (1.7% vs. 2.0%; p = 0.6) or 30-day mortality (2.2% vs. 2.7%; p = 0.5) between groups. Similarly, the TAVI group presented a comparable 30-day stroke risk (2.4% vs. 2.2%; p = 0.6) to the SVA group, but had a higher risk of aortic valve reintervention (HR = 2.13; p = 0.03). In the TAVI cohort, 1% of patients (n = 11) required conversion to SVA. There were no significant differences in the risk of heart failure within the first year of follow-up between the TAVI and SVA groups. However, the TAVI group showed a higher heart failure risk after 1 year compared to the SVA group (HR = 2.02; p = 0.04).

TAVI was associated with lower rates of in-hospital acute kidney injury (6.4% vs. 17.8%; p < 0.01), blood transfusion (3.2% vs. 18.2%; p < 0.01), and new-onset AF (2.7% vs. 28.7%; p < 0.01), as well as shorter hospital stays (median: 2 days, interquartile range: 1–3 days vs. 6 days, interquartile range: 5–8 days; p < 0.001). However, it was linked to a higher risk of permanent pacemaker implantation (11.5% vs. 6.7%; p < 0.001) and significant residual paravalvular leakage (1% vs. 0.2%; p = 0.03).

Based on these findings, the study concludes that patients with pure native aortic insufficiency treated with currently available TAVI devices experience fewer short-term complications and comparable short-term mortality, whereas SVA is associated with better clinical outcomes in the mid-term follow-up.

COMMENTARY:

The outcomes observed align with expectations, although the proportion of patients with pure aortic insufficiency assigned to TAVI in the U.S. is noteworthy. Additionally, the authors attempted to improve post-procedure results through confounding control using weighted propensity score analysis. However, residual confounding persists, as the TAVI group remains older and with more comorbidities prior to adjustment. Furthermore, certain factors, such as prior thoracic radiation, fragility indicators, and degree of left ventricular remodeling, were not considered despite potentially influencing treatment decisions. Additionally, the impact of concomitant myocardial revascularization, performed in 30% of surgical patients but only 2% of TAVI patients, remains unclear and may affect patient outcomes due to possible residual ischemia.

These aspects, along with factors such as residual paravalvular leakage or pacemaker implantation, could significantly impact survival, with a potentially more pronounced effect as follow-up time extends.

Considering the current device limitations, a critical question for the future is whether the development of TAVI devices specifically designed for pure aortic insufficiency could overcome the challenges identified thus far. Results from the ALIGN-AR trial (JenaValve® Pericardial TAVR Aortic Regurgitation Study), which investigates the transfemoral JenaValve® Trilogy® system for high-risk patients with aortic insufficiency, may shed light on this issue when published at the end of 2023. Until then, the existing data suggest that off-label TAVI use should be reserved for patients with aortic insufficiency, calcification, and no surgical alternative. Another aspect worth considering is comparing outcomes in this patient group with minimally invasive surgical approaches, where more competitive results may favor surgery.

REFERENCE:

Mentias A, Saad M, Menon V, Reed GW, Popovic Z, Johnston D, et al. Transcatheter vs. surgical aortic valve replacement in pure native aortic regurgitation. Ann Thorac Surg. 2023 Apr;115(4):870-876. doi: 10.1016/j.athoracsur.2022.09.016.

Ranard LS, Vahl TP, Thourani VH. Weighing transcatheter aortic valve replacement vs. surgical aortic valve replacement for native aortic regurgitation. Ann Thorac Surg. 2023 Apr;115(4):877-878. doi: 10.1016/j.athoracsur.2023.02.001.