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Squeezing TAVR into a very narrow funnel

For several decades, surgical valve replacement has been the mainstay of treatment for symptomatic valvular aortic stenosis (AS), considered a Class I recommendation by the American and European guidelines. In properly selected individuals, this surgical procedure offers considerable improvements in symptoms and life expectancy. Nonetheless, a large number of patients do not undergo surgery due to their high or “extreme” risk. For those individuals, transcatheter aortic valve replacement (TAVR) has become a potentially life-saving procedure. In the Placement of Aortic Transcatheter Valves (PARTNER) trial, TAVR resulted in a 20% reduction in mortality at 12 months in a cohort of surgically inoperable patients (cohort B) when compared to medical treatment [1]. With these results in mind, the Food and Drug Administration (FDA) has approved TAVR for the treatment of inoperable patients with AS meeting the PARTNER-B criteria. Nonetheless, it is unclear how the FDA eligibility criteria would fit in relation to the overall AS population. In this issue of Catheterization and Cardiovascular Interventions, Babcock et al. investigated the prevalence of patients with AS fitting the PARTNERS-B criteria within an AS population who underwent echocardiographic evaluation at a highvolume tertiary medical center [2]. From a total of 21,652 patients screened by transthoracic echocardiography over a 3-year period, the authors found 833 (3.8%) patients with AS. Only 133 patients had symptomatic moderate-to-severe or severe AS (0.65% of the entirely screened population and 20% of the overall AS group). Of note, 18 of those 133 (0.2% of the overall AS population) patients were eligible according to the PARTNER-B criteria [2]. As it is recommended to perform around 20–24 cases per year to acquire and maintain procedural proficiency, it appears from this study results that only centers with high referral volumes would be able to keep up with those referral numbers and run a TAVR program. Nonetheless, outside the US, it is pretty standard to perform TAVR in (operable) patients with high surgical risk, and the FDA will soon approve TAVR for this particular indication. In the case of patients with intermediate risk, clinical outcome data is still awaiting the results of two on-going large clinical trials (SURTAVI and PARTNERS 2). So far, only one study investigated the role of TAVR in intermediate patients. In that prospective, propensity matched comparison, 255 intermediate risk patients (STS score between 3 and 8 percent) who underwent TAVR were matched to patients undergoing surgical replacement. In that study, both groups had similar mortality at 30 days and 1 year. Despite the paucity of data, many operators around the world are already performing this procedure for this particular indication. Additionally, patients with large aortic annulus (>25 mm), previously excluded from the PARTNERS trials, are currently receiving large (29 and 31-mm) prosthetic valves with low postprocedural paravalvular leak rates [3]. Indeed, as technology evolves and heart teams become more experienced, indications for TAVR will inevitably grow, even before obtaining solid outcome data for each new indication (i.e., intermediate and low surgical risk individuals with AS, patients with aortic valve regurgitation, valve-in-valve procedures, or patients with renal insufficiency). Since the first TAVR performed in 2002 by Alain Cribier, it is estimated that> 80,000 patients have had TAVR. Throughout these 10 years, we have gained a tremendous knowledge about TAVR. Among many key concepts we should mention the need for collaborative heart team approach, careful patient selection with the implementation of risk score assessment, as well as the development of guidelines for standardization of endpoint definitions. Currently, TAVR is associated