Reviewing a new meta-analysis comparing survival outcomes in patients treated with TAVI versus aortic valve replacement (AVR), with a focus on the studies and the follow-up of currently available evidence, may lead to the tedium of a nearly predictable outcome: benefit for TAVI in the first two years, a technical draw in the short period that follows, and surgical benefit thereafter. However, the authors of this work introduce a twist by providing data that had previously been unavailable, allowing for an unexpected reconsideration of the evidence.

The minimally invasive approach to the aortic valve (mini-AVR) has been revisited over the past decade, given that it was a previously known technique that had likely been abandoned due to a lack of motivation within the surgical community. In a competitive environment such as the present, those who believed in preserving chest stability for better early perioperative results and in surgical bioprosthesis implantation for favorable long-term outcomes endured the disappointment of a technical alternative that had yet to gain traction over the sternotomy approach. Mistakenly labeled “conventional,” since a highly technical, complex procedure is anything but conventional. Against TAVI, the almost non-existent inclusion rate of mini-AVR in clinical trial protocols condemned it to exclusion from decision algorithms, with its field of application reduced alongside its partner, the “conventional” approach.

This study offers a fresh perspective with previously unavailable data for three reasons: it performs the most extensive meta-analysis of mini-AVR vs. TAVI to date; it presents an analysis at the patient level rather than at the study level, almost resembling a multicenter propensity-adjusted study with substantial statistical power; and it leverages data from studies that could not previously be analyzed, using an advanced computational methodology to examine Kaplan-Meier curve cancellations, extracting raw individual data that the authors of the original studies had not intended to publish. This methodology, now increasingly popular in creating meta-evidence, is a transparency exercise that should be demanded from original studies. Tools like WebPlotDigitalizer enable this type of high-value analysis.

All analyses were designed using an all-comers approach, covering patients with multiple risk profiles, provided they were properly adjusted. All available evidence from propensity-adjusted observational studies and clinical trials among the three treatment options—TAVI, AVR, and mini-AVR—was included. For the TAVI vs. AVR comparison, trials such as Evolut Low Risk, US CoreValve, NOTION, SURTAVI, UKTAVI, and the PARTNER series (1, 2, and 3) were analyzed alongside a few observational studies. The analysis yielded unsurprising results in a 4-5-year follow-up of individual patients: improved survival with AVR beyond two years and a technical draw when the analysis was restricted to clinical trial data and the TAVI cohort with transfemoral access.

However, before giving in to discouragement, it is worth highlighting the results from 11 propensity-adjusted studies of TAVI vs. mini-AVR, with 1,497 and 1,318 patients in each arm, respectively, all well-designed with low bias risk. Regarding surgical risk, one study included low-risk patients, two moderate-risk, four high-risk, and four had mixed risk profiles. Mortality with mini-AVR was nearly half that with TAVI (HR = 0.56, 95% CI 0.46 – 0.69; p < 0.01), with separation of the curves in early post-procedure phases and extended benefit over a maximum follow-up of 6 years. Sensitivity analysis confirmed that no individual study accounted for the observed outcome.

The authors conclude that despite the long-term survival benefit of AVR over TAVI, mini-AVR further enhances the advantage of the surgical option. This finding should be considered in the design of future clinical trials.

COMMENTARY:

As acknowledged by the authors, this is the first study to robustly analyze the treatment alternatives AVR, mini-AVR, and TAVI through a patient-level meta-regression with extended follow-up.

While it may be viewed as just another study, evidence of this kind is necessary to gauge the reality. In fact, its publication in the American Journal of Cardiology speaks to its significance. Firstly, it allows for real-world data (multicentricity, multiple risk profiles) with less controlled populations, since many of the patients we encounter in decision-making sessions may not meet the inclusion criteria of renowned clinical trials. Secondly, procedures are performed at multiple centers, with real-world outcomes and technical variations in both interventional and surgical approaches. With the early clinical trials, transcatheter therapy was still in its technological infancy, and from a current perspective, it is no longer viable to isolate outcomes based on the chosen access route. Today, all units have access to multiple approaches with different devices, allowing the selection of the best option according to the assigned treatment. Consequently, if TAVI is chosen, the results are equally analyzable “regardless of the route.” In the case of surgery, most mini-AVR cases analyzed were via mini-sternotomy, though mini-thoracotomy approaches were also included. The prostheses implanted were primarily sutureless (Livanova® Perceval®) or rapid deployment (Edwards® Intuity®). This surgical population is vastly different from those included in clinical trials, where TAVI—a high-tech alternative—is compared to a surgical approach that, rather than “conventional,” might be better described as classical to antiquated. Worse yet, our decision-making guidelines are based on a supposedly equal comparison that is in reality highly unequal.

Therefore, the analyzed study brings hope for a resurgence of the surgical option, a sign that the seemingly categorical indications are not as well-defined as presumed, and a call to continue offering an updated surgical therapeutic alternative. The comeback for surgeons should not only involve adopting transcatheter therapies but also continuing to offer surgical options adapted to today’s times, resources, and patient needs. What began over 10 years ago as a hopeful outlook with J-sternotomies, superior vena cava venous cannulation, and changes in cardioplegic strategy now appears to bear fruit. We hope these or other authors will provide new subgroup analyses by risk groups between TAVI and mini-AVR and that new clinical trials will be planned to balance the competition. Based on the discussion, the final whistle has yet to blown—there is still game time left.

REFERENCE:

Fong KY, Yap JJL, Chan YH, Ewe SH, Chao VTT, Amanullah MR, et al. Network meta-analysis comparing transcatheter, minimally invasive, and conventional surgical aortic valve replacement. Am J Cardiol. 2023 May 15;195:45-56. doi: 10.1016/j.amjcard.2023.02.017.