Paradigm Shift in the Management of Aortic Stenosis

Clinically significant aortic stenosis (AS) affects 1.6% of adults over the age of 65 years ¹ and, if left untreated, has a dismal prognosis. ² Aortic valve replacement (AVR) is the only proven therapy for patients with severe, symptomatic AS. ³ Two different AVR modalities (surgical or transcatheter) are available; both with distinct safety profiles.

In this issue of the Journal of the American Heart Association (JAHA), Harvey et al examined trends in complications among patients undergoing surgical aortic valve replacement (SAVR) and transcatheter (TAVR) aortic valve replacement in the United States. ⁴ They conducted a retrospective analysis using a Medicare fee‐for‐service (FFS) data set, which included all beneficiaries ≥65 years of age with at least 6 months of continuous enrollment. Patients who needed concomitant surgical procedures, nontransfemoral access, or had infective endocarditis were excluded. The purpose of their analysis was to assess temporal trends in short‐term complications among Medicare FFS beneficiaries receiving TAVR or SAVR during an 8‐year period (2012–2019).

The primary end point of the study was a composite of major in‐hospital or 30‐day complications defined as death, new atrial fibrillation, acute kidney injury, acute myocardial infarction, aortic rupture, bleeding, postoperative infection, pacemaker placement, ventilation >48 hours, respiratory failure, stroke, sepsis, or vascular complications.

Of 429 967 Medicare FFS beneficiaries who underwent AVR during the study period, 211 212 met the inclusion criteria (45%) set by the investigators. Of these patients, 146 238 underwent TAVR (69%) and 64 973 isolated SAVR (31%). Patients with TAVR were older (mean age TAVR, 80.6 years [6.9] versus SAVR 74 years [6]) and had more comorbid conditions than patients with SAVR (mean Elixhauser Comorbidity Index, TAVR 6.4 [3.5] versus SAVR 4.4 [2.7]).

A number of key findings of the study are noted. First, the number of AVR procedures increased 3‐fold, from 13 310 procedures in 2012 (25 per 100 000 Medicare FFS beneficiaries) to 40 015 procedures in 2019 (62 per 100 000 Medicare FFS beneficiaries). Second, the proportion of SAVR decreased from 75% in 2012 to 10% in 2019, with concomitant increases in TAVR procedures (Figure). Third, short‐term complications for TAVR were lower than SAVR in all periods. The overall trend in short‐term complications during the study period was favorable (ie, fewer complications over time) for both procedures, although the Δ was significantly more pronounced for TAVR (22%) than for SAVR (4%). In the last year of the study (2019), the most common complication among patients with TAVR was pacemaker implantation, whereas for patients with SAVR, the most common complications were new atrial fibrillation and acute kidney injury.

Figure 1. Frequency and distribution of AVR modality among Medicare FFS beneficiaries in 2012 (left) and 2019 (right).

The number of AVR procedures increased 3‐fold during the study period, with a predominance of TAVR over SAVR (90%/10%) at the end of the study period. AVR indicates aortic valve replacement; FFS, fee‐for‐service; SAVR, surgical aortic valve replacement; and TAVR, transcatheter aortic valve replacement.

What does this mean for patients? These data are good news for patients with AS for several reasons. First, more patients with severe AS are being treated. For a lethal disease with no established medical therapy, the reported 3‐fold increase in AVR is perhaps the most remarkable finding of the study. Irrespective of the AVR modality, the fact that more patients are being treated is significant progress. Second, and perhaps unsurprisingly, more patients with AS are receiving the less invasive form of AVR (TAVR) upfront. This remarkable change in clinical practice is supported by rigorous clinical trials conducted over the past 2 decades, which compared TAVR and SAVR in patients with increasingly lower risk profiles. ⁵ , ⁶ , ⁷ , ⁸ , ⁹

This change in practice in favor of TAVR over SAVR has implications that extend far beyond the 30‐day period. This has created new questions, including the repeatability of the TAVR procedure to address structural and nonstructural valve deterioration, as part of the lifetime management of AS. ¹⁰ Finally, short‐term complications for SAVR and TAVR are trending in the right direction, with significantly fewer complications noted in the most contemporary periods. These positive trends in short‐term complications are likely multifactorial. Computed tomography enables better patient selection and valve sizing, device iterations to mitigate the risk of paravalvular regurgitation are present in all commercially available valve platforms at present, and expandable or in‐line sheaths that facilitate transfemoral access and decrease the risk of valvular complications are also available. Finally, the procedure itself has also been refined with novel implantation techniques, such as cusp overlap, that help reduce implantation depth and conduction abnormalities. ¹¹

What to make of the fact that short‐term complications are improving at a much faster rate for TAVR than for SAVR? One should resist the temptation to make too much out of this finding. First, as the authors pointed out, both procedures are at very different stages in their natural evolution. Second, some of the complications selected (atrial fibrillation, prolonged intubation, postoperative infection) disproportionally affect one procedure (SAVR). Third, although short‐term complications are extremely important outcomes, long‐term outcomes and future interventions are equally important for patients with long life expectancies, which remains unclear. Finally, there have been important changes in surgical practice, in particular, the use of larger surgical valves and minimally invasive AVR, which a retrospective study will not be able to fully capture. ⁵ , ¹²

Notwithstanding, some common limitations of retrospective analysis of large administrative databases, the study provides an important benchmark to the rapidly evolving field of transcatheter and surgical therapies for valvular heart disease. The commercial introduction of TAVR has been the equivalent of a rising tide that elevated the standard of care (AVR) for all patients with AS.

Disclosures

Dr Kaneko is on the advisory board for Edwards, Abbott, Johnson and Johnson, and serves as a consultant for Medtronic. Dr Garcia is a steering committee member for Edwards (Alliance Trial) and Abbott Vascular (Envision Trial), and serves as a consultant and proctor for Medtronic, Abbott Vascular, and Edwards Lifesciences.